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1
Zaupa, Giovanni. "Sistemi multivalenti e cooperativi per la catalisi biomimetica." Doctoral thesis, Università degli studi di Padova, 2009. http://hdl.handle.net/11577/3426105.
Full textAbstract:
The exceptionally efficient molecular recognition and catalysis events observed in Nature result from a highly cooperative interplay between functional groups. Both the processes of recognition and catalysis rely on two key issues:
· Multivalency. The presence of multiple functional groups enhances the binding affinity because of the exerted cooperativity. A similar cooperativity is generally observed in the catalytic site of enzymes.
· Functional group diversity. Intrinsically, proteins are heterofunctional structures exploiting a wide variety of functional groups for target recognition or for substrate conversion.
Based on these concepts, this research project aims at developing artificial systems with competitive performances.
Starting point for this project are recent results obtained in our group which are:
· The development of a synthetic protocol for the functionalization of multivalent (3) scaffold molecules on solid support.
· The observation of strong catalytic cooperativity between functional groups (Zn-complexes) attached to the periphery of dendrimers or self-assembled on the surface of Au-nanoparticles.
The initial aim will be to apply the synthetic protocol for the functionalization of dendrimers of various generations. The ability to functionalize dendrimers on solid support is highly interesting by itself, because it greatly facilitates compound purification, which is the main obstacle in dendrimer synthesis. In the next phase, dendrimers will be modified with appropriate functional groups. Functional group diversity can be introduced by doping the dendrimer with mixtures of functionalities. With the same objectives, but using a different synthetic strategy, the functionalization and application of Au-nanoparticles will be an alternative.<br>La grande efficienza che si può osservare in natura nel riconoscimento molecolare e nella catalisi è il risultato dell’interazione cooperativa tra gruppi funzionali. Sia il processo di riconoscimento sia quello di catalisi si basano su due caratteristiche fondamentali:
- Multivalenza. La presenza di numerosi gruppi funzionali aumenta l’affinità di legame per effetto cooperativo. Questo si osserva anche nel sito catalitico degli enzimi.
- Diversità di gruppi funzionali. Le proteine sono strutture eterofunzionali che presentano una larga varietà di gruppi funzionali per il riconoscimento di un target o per la conversione di un substrato.
Il progetto di ricerca riguarda quindi lo sviluppo di sistemi artificiali basati su queste caratteristiche.
Il punto di partenza sono per il progetto sono alcuni risultati ottenuti dal nostro gruppo di ricerca:
- Lo sviluppo di un protocollo sintetico per la funzionalizzazione di piattaforme molecolari multivalenti su un supporto solido.
- L’osservazione di un forte effetto cooperativo in catalisi tra gruppi funzionali (complessi di zinco) legati alla periferia di dendrimeri o auto-assemblati sulla superficie di nanoparticelle di oro
L’obiettivo iniziale sarà l’applicazione di un protocollo sintetico per la funzionalizzazione di dendrimeri di varie generazioni. La possibilità di funzionalizzare dendrimeri su un supporto solido risulta di per sè molto interessante, in quanto faciliterebbe notevolmente la purificazione dei composti, che è la difficoltà maggiore nella sintesi dei dendrimeri. Nella fase successiva i dendrimeri saranno modificati con appropriati gruppi funzionali. La diversità di gruppi funzionali sarà ottenuta introducendo sui dendrimeri miscele di funzionalità.
Considerando le loro dimensioni, l’idea è quella di utilizzare questi dendrimeri nel riconoscimento di grandi strutture, come la superficie di proteine. Per gli stessi scopi, ma usando una differente strategia sintetica, la funzionalizzazione e l’applicazione di nanoparticelle d’oro sarà un’alternativa.
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ROSSI, LORENZO. "Development of Biomaterials for Translational Medicine Applications: Pancreatic β-cells Imaging, Pseudomonas Aeruginosa Treatment, Tissue Engineering". Doctoral thesis, Università degli Studi di Milano-Bicocca, 2023. https://hdl.handle.net/10281/402361.
Full textAbstract:
Considerando che la prima definizione strutturata di biomateriali è stata formulata solo 50 anni fa, e che 100 anni fa i biomateriali come li conosciamo ora non esistevano nemmeno, possiamo affermare che rappresentano un punto cruciale del progresso scientifico, rivoluzionando la biomedicina. Molti aspetti della medicina clinica, compreso il trattamento di patologie croniche, il delivery di piccole molecole, la produzione di dispositivi medici e l’ingegneria tissutale non sarebbero gli stessi senza i recenti sviluppi di questa classe di materiali. L’ampia gamma di applicazioni per cui possono essere progettati, le caratteristiche uniche e la possibilità di adattare il costrutto finale ad un’ampia varietà di scopi garantiscono un interesse ancora molto elevato attorno al loro sviluppo. La possibilità di implementare nuovi aspetti e tecnologie e ottenere prodotti più complessi rende i biomateriali validi candidati per affrontare delle sfide aperte nel trattamento di molteplici condizioni patologiche ed espandere i confini della medicina moderna.
In questa tesi, viene proposta, per molteplici applicazioni, la derivatizzazione chimica e la formulazione di polimeri sia di origine sintetica sia naturale. La combinazione di diverse classi di polimeri e le loro proprietà, oltre allo sfruttamento del concetto di multivalenza, sono alla base di tutti i progetti presentati.
Viene descritto lo sviluppo di nanoparticelle polimeriche multimodali, basate su una combinazione di acido poli-γ-glutammico e chitosano, per la visualizzazione delle isole pancreatiche e delle cellule β derivate da cellule staminali pluripotenti indotte. Questo tipo di strumento potrebbe essere cruciale nella trasposizione in clinica di terapie rigenerative per il diabete di tipo 1, basate sull’utilizzo di pancreas bio-artificiali, dal momento che consente l’imaging di specifiche cellule ad alta sensibilità e quindi il monitoraggio della vitalità all’interno di questi tipi di dispositivi. Queste nanoparticelle sono versatili e, decorandole con diversi agenti di targeting e detecting, è possibile sviluppare nanomateriali adatti al monitoraggio della sopravvivenza, attecchimento, proliferazione e funzione di trapianti cellulari e lo sviluppo e validazione dell’applicazione di tecnologie di imaging all’avanguardia che facilitano l’impiego di nuove terapie rigenerative su modelli preclinici con animali di grandi dimensioni e su pazienti.
Inoltre, è stata sviluppato uno scaffold polimerico lineare basata su un polimero sintetico coniugato con un analogo del naturale delle cellule β pancreatiche (exendina-4, Ex4), e può portare a nuovi agenti terapeutici o di diagnostica. Infatti, il polimero presenta più siti disponibili per successiva coniugazione di ulteriori oggetti. I prodotti sintetizzati possono essere utilizzati anche come vettori per il rilascio controllato di Ex4.
Un altro coniugato polimerico è stato sviluppato e studiato, in concomitanza con una libreria di piccole molecole basate sul mannosio, per il trattamento del batterio Pseudomonas Aeruginosa. In questo caso, il chitosano è stato scelto come componente polimerica, sfruttando la sua tenue attività antibatterica e la possibilità di essere usato come scaffold, combinato con la capacità di interagire con LecB di solfonati e solfossimmine derivati dal mannosio, che sono stati coniugati al polimero.
Infine, un idrogelo ibrido composto da acido ialuronico e gelatina è stato sviluppato per la biostampa 3D con cellule U87. L’idrogelo proposto è reticolato chimicamente e ricorda con le sue specificità la matrice extracellulare naturale cerebrale in composizione e caratteristiche. Questo tipo di materiale può servire come modello 3D di glioblastoma e può essere utilizzato per uno screening più affidabile e conveniente di farmaci antitumorali, anche considerando l’elevata malignità, resistenza verso trattamenti antitumorali e alto tasso di ricorrenza del tumore.<br>Considering that the first structured definition of biomaterials was given only 50 years ago and that 100 years ago biomaterials, as we think about them today, did not even exist, we could claim they have been a crucial point in scientific advances, as they revolutionized many aspects of biomedicine. Thinking about the state-of-the-art of many fields in medicine and biotechnologies, biomaterials are widely employed. Many aspects of clinical medicine, including chronic conditions treatment, drug delivery, medical device manufacturing, and tissue engineering would not be the same without all the recent advances in the development of this class of materials. The wide range of applications they can be designed for, the unique characteristics, and the possibility to tune them and adapt the final construct for an extended variety of cases and purposes ensure a still high hype around their development. Even though much progress has been made, the possibility to implement new aspects and technologies and obtain more smart and complex products makes biomaterials valid candidates to face opening challenges in the treatment of multiple pathological conditions and expand the boundaries of modern medicine.
In this thesis, the chemical derivatization and formulation of polymers of both synthetic and natural origin for multiple applications are proposed. The combination of different classes of polymers and so of their properties, and the exploitation of the concept of multivalency, underlie all the presented projects.
Hence, we show the development of multimodal polymeric nanoparticles, based on a combination of poly-γ-glutamic acid (γ-PGA) and chitosan, for the imaging of porcine pancreatic islet and induced pluripotent stem cell-derived β-cells. This kind of tool might be crucial in the clinical translation of type 1 diabetes regenerative therapies involving bio-artificial pancreas, since it allows the imaging of specific cell types with high sensitivity and therefore the monitoring of β cells viability inside this kind of device. The proposed nanoparticles are highly versatile, and by decorating different targeting and detecting agents it is possible to develop nanotools suitable for monitoring of survival, engraftment, proliferation, function, and whole-body distribution of the cellular transplants and the development and validation of the application of state-of-the-art imaging technologies facilitating the provision of new regenerative therapies to preclinical large animal models and patients.
Furthermore, a linear polymeric scaffold based on a synthetic polymer conjugated to an analogue of natural ligand of pancreatic β-cells (exendin-4, Ex4) has been developed, and can lead to new therapeutics and diagnostics agents. Indeed, the polymer displays more available sites for subsequent conjugation of other entities. The synthesized compounds may function per se as Ex4 controlled release carriers.
Another polymeric conjugate, together with a library of mannoside-based small molecules, has been designed and studied for the treatment of Pseudomonas Aeruginosa bacterium. In this case, chitosan has been selected as polymeric component, exploiting its mild antimicrobial activity and its capability to serve as a linear scaffold and combining it with the lectin B targeting capability of mannoside-derived sulfonates and sulfoximines.
Lastly, a hybrid hydrogel made of hyaluronic acid and gelatin has been developed for 3D bioprinting with U87 cells. The proposed hydrogel is chemically crosslinked and resembles in its features the natural extracellular matrix (ECM) brain composition and characteristics This kind of material may serve as a model of glioblastoma for 3D cell culture and can be used for more reliable and convenient antitumoral drug screening routes, considering the high malignancy, resistance towards antitumoral treatments and the high recurrence rate.
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Salvadó, Molero Míriam. "Synthetic glycolipids as modulators of carbohydrate-protein interactions." Doctoral thesis, Universitat Rovira i Virgili, 2016. http://hdl.handle.net/10803/456813.
Full textAbstract:
El Capítol 1 presenta una descripció general de la glicobiologia així com el rol dels sistemes multivalents en la interacció carbohidrat-proteïna. En el Capítol 2 s’estableixen els objectius generals.
El Capítol 3, fa referencia a la síntesi de glicolípids que presenten modificacions a l’anell de piranosa o a la part de l’aglicona. La avaluació tant d’aquest glicolípids com els seus corresponents sistemes multivalents es va dur a terme front glicosidases.
Es va trobar, que les modificacions tant en l’anell de piranosa com en l’aglicona jugaven un paper important en la inhibició. A més a més, el glicocluster que presenta 4 glicolípids va donar la millor potencia d’inhibició per carbohidrat.
En el Capítol 4 es descriu la síntesi d’estructures multivalent amb dos estructures centrals (polímers hiperramificats i dendrimers) que permeten la presentació dels carbohidrats d’una manera polidispersa o monodispersa. La unió amb una determinada proteïna va ser estudiada emprant les tècniques del DLS i SPR. Interaccions mes fortes en solucions diluïdes de proteïna, es van trobar pel sistemes multivalent polidispersos.
En el Capítol 5 s’explora una estratègia novell pel disseny de inhibidors multivalents basats en nanocapsules. Per trobar com afecta la diferent arquitectura dels glicodendrimers in la unió amb proteïnes, experiments de BLI es van duu a terme per determinar el valor del IC50. La modificació selectiva a proteïna també va ser estudiada per una futura formació de les nanocapsules.
La recerca en el Capítol 6 explora la síntesi de fluorosucres com a reactius en la construcció de fluoroglicoproteïnes. Una estratègia general per accedir a un ampli ventall de fluorosucres, via iodurs de glicosil com intermedis, degut al que son reactius útils per la modificació selectiva de proteïnes es va donar a conèixer.
El Capítol 7 presenta les observacions finals i les conclusions extretes dels resultat obtinguts.<br>El Capítulo 1 presenta una descripción general de la glicobiologia así como el rol de los sistemas multivalentes en la interacción carbohidrato-proteína. En el Capítulo 2 se establecen los objetivos generales.
El Capítulo 3, hace referencia a la síntesis de glicolípidos que presentan modificaciones en el anillo de piranosa o en la aglicona. La evaluación tanto de estos glicolípidos como sus correspondientes sistemas multivalentes frente glicosidasas se llevó a cabo.
Se encontró, que las modificaciones tanto en el anillo de piranosa como en la algicona jugaban un papel muy importante en la inhibición. A más a más, el glicocluster que presenta 4 glicolipidos dio mejor potencia de inhibición por carbohidrato.
En el Capítulo 4 se describe la síntesis de sistemas multivalentes con dos estructuras centrales (polímeros hiperramificados o dendrimeros) que permiten la presentación de los carbohidratos de una manera polidispersa o monodispersa. La unión con una determinada proteína fue estudiada utilizando las técnicas de DLS y SPR. Interacciones mas fuertes en soluciones diluidas de proteína, fueron encontradas para los sistemas multivalentes polidispersos.
En el Capítulo 5 se explora una estrategia novel para el diseño de inhibidores multivalentes basados en nanocapsulas. Para encontrar como afecta la diferente arquitectura de los glicodendrimeros en la unión con proteínas, experimentos de BLI fueron llevados a cabo para determinar el valor del IC50. La modificación selectiva a proteína también fue estudiada para una futura formación de las nanocapsulas.
En el Capítulo 6 se explora la síntesis de fluoroazúcares como reactivos en la construcción de fluoroglicoproteinas. Una estrategia general para acceder a un amplio abanico de fluoroazúcares, via, ioduros de glicosilo como intermedios, debido a que son reactivos útiles para la modificación selectiva de proteínas se dio a conocer.
El Capítulo 7 presenta las observaciones finales i las conclusiones extraídas de los resultados obtenidos.<br>Chapter 1 contains a general introduction that describes the importance of glycobiology and the role of multivalent systems in the study of carbohydrate-protein interactions. Chapter 2 sets out the general objectives of this thesis.
The research in Chapter 3 describes the synthesis of a series of glycolipids that presents modifications either in the pyranose ring or in the aglycone moiety and their evaluation as potent inhibitors, together with multivalent systems that presents glycolipids, against glycosidases.
It was found that modifications in the aglycone moiety and in the pyranose ring played important role in potency. Moreover, glycocluster that presents 4 glycolipids monomers gave the best inhibitor potency per sugar.
The research in Chapter 4 describes the synthesis of multivalent structures with two different central cores (hyperbranched polymers and dendrimers) that allow the presentation of carbohydrate residues in a polydispers or monodispers manner. Binding was detected using DLS and SPR techniques. Strong interactions in a non-saturated protein concentration, revealed by aggregates formation and binding, were found for polydispers multivalent systems.
The research in Chapter 5 explores a novel strategy for the design of multivalent inhibitors based on glycodendriprotein-based nanocapsules. In order to explore how the different glycodendrimer architecture affects the binding properties, BLI experiments were carried out to determine the IC50 of the tested glycodendrimers. The site selective protein modification was also studied for a further glycodendriprotein-based nanocapsules formation.
The research in Chapter 6 explores the synthesis of fluorosugar reagents for the construction of well-defined fluoroglycoproteins. A general strategy to access a wide range of fluorosugars, via a glycosyl iodide intermediate, that are useful reagents for chemical-site selective protein glycosylation were disclosed.
Chapter 7 presents the final remarks and conclusions extracted from the results obtained in this thesis.
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Grillaud, Maxime. "Design and synthesis of multifunctional adamantane-based dendrons for biological applications." Thesis, Strasbourg, 2014. http://www.theses.fr/2014STRAF021.
Full textAbstract:
Les polymères synthétiques tels que les dendrons ou les dendrimères possèdent des propriétés structurales intéressantes. Leur monodispersité et leur synthèse étape par étape permet de contrôler et de caractériser totalement leur structure. De plus, la multivalence offre aux vecteurs une meilleure affinité d’interactions entre plusieurs copies d’un ligand lié au dendron/dendrimère et le récepteur désiré en comparaison au ligand seul. L’adamantane est une molécule rigide et stable dont plusieurs dérivés ont été commercialisés pour des applications thérapeutiques, principalement comme agents antiviraux. De plus, il est possible de le fonctionnaliser sur 4 positions symétriques via des synthèses organiques. Sa conformation 3D permet d’amoindrir les encombrements stériques entre les groupements fonctionnels. Nous avons alors choisi de combiner les propriétés de l’adamantane et des dendrons afin de construire de nouveaux vecteurs synthétiques. Leurs synthèses s’effectuent avec de hauts rendements et chaque nouveau composé a été totalement caractérisé par les différentes techniques d’analyses chimiques et structurales. Les dendrons à base d’adamantane polycationiques non cytotoxiques ont révélé une forte pénétration cellulaire permettant de mieux comprendre les mécanismes d’internalisation des dendrons. Ils ont également été évalués pour la formation de complexes avec un plasmide d’ADN. Des modifications sur leurs structures ont amélioré leur capacité à interagir avec l’acide nucléique grâce à la modification du point focal. Enfin, un peptide thérapeutique aux propriétés protectrices dans le lupus érythémateux disséminé, P140, a été couplé à un dendron à base d’adamantane à 3 branches et nous avons analysé les effets biologiques du trimère en comparaison avec le monomère<br>Dendrons (wedge-shaped dendrimer sections) have been investigated as ideal nanoscale carrier molecules for the delivery of bioactive materials into the cells. Molecular engineering of these hyperbranched, monodisperse, well-defined structures can be easily performed using simple organic synthesis. Multivalency constituted by the multiple surface groups at the periphery of a dendron promotes higher binding affinity for ligand/receptor interactions. Adamantane molecule is a rigid structure consisting of four cyclohexane rings fused in chair conformation. The well-defined 3D conformation, the hydrophobicity and the lipophilicity provide to adamantane-based compounds favorable properties for their transport through biological membranes. In this context, the first part of this work was focused on the design and the synthesis of a novel type of polycationic dendrons based on adamantane, which are able to penetrate into cells without triggering cytotoxic effects. The next study of this Thesis concerned the investigation of our polycationic adamantane-based dendrons for gene delivery. We evaluated the capacity of the dendrons to complex a plasmid DNA. Hydrophobic compounds (biotin and cholesterol) were covalently bound to the focal point of the dendrons via “click” chemistry and the effects of the dendron generation, the peripheral cationic groups, and the hydrophobic modifications on the formation and stability of the complexes were studied. Finally, the dendrons constituted of an adamantane core, a focal point and three arms, were synthetized starting from a multifunctional adamantane derivative. We have coupled P140, a therapeutic peptide with protective properties in systemic lupus erythematosus, to an adamantane-based dendron and we have analyzed the biological effects of the resulting trimer compared to the monomer
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Bachem, Gunnar. "Investigation of Cooperativity between Statistical Rebinding and the Chelate Effect on DNA Scaffolded Multivalent Binders as a Method for Developing High Avidity Ligands to target the C-type Lectin Langerin." Doctoral thesis, Humboldt-Universität zu Berlin, 2021. http://dx.doi.org/10.18452/22787.
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Aufgrund der Fähigkeit von Langerhans Zellen, welche den C-Typ Lektin (CTL) Rezeptor Langerin exprimieren, Antigene zu internalisieren und T-Zellen zu präsentieren, wurde Langerin als attraktives Ziel für neue Immunotherapien erkannt. Langerin kann Pathogene wie z.B. Viren erkennen, die zur Erhöhung der Avidität Kohlenhydratliganden multivalent präsentieren, da die monovalenten Kohlenhydratliganden nur niedrige Affinitäten für Langerin aufweisen. Die natürlichen monovalenten Kohlenhydratliganden besitzen nur niedrige Affinitäten für Langerin. Inspiriert durch die Natur stellt Multivalenz eine Strategie zur Überwindung der schwachen CTL-Kohlenhydrat-Wechselwirkung dar. Im Gegensatz zur hochmultivalenten Präsentation von Liganden mit undefinierter Anordnung hat sich diese Arbeit zum Ziel gesetzt auch die Ökonomie der Liganden zu optimieren, indem Liganden auf einer DNA Gerüststruktur so präsentiert wurden, dass sie die Distanz zwischen den Bindungstaschen des Homotrimers Langerin wiederspiegeln. Eine Untersuchung der relevanten multivalenten Bindungsmechanismen führte zu einer Anordnung der Liganden, die sowohl statistisches Rebinding als auch den Chelate Effekt einbezog. Der Rebinding Effekt wurde als Mittel erkannt, dass nicht nur die Avidität des Liganden an einer Bindungstasche erhöht, sondern auch ausgenutzt werden kann, um den Chelate Effekt zu amplifizieren. Diese Methode stellt eine Möglichkeit dar niedrige oder nicht vorhandene Multivalenzeffekte bei der bivalenten Präsentation von Liganden zu überwinden, wenn hochaffine Liganden nicht zur Verfügung stehen. Eine Kombination dieser Strategie mit der Entwicklung eines neuen selektiven Liganden für Langerin führte zu dem stärksten bekannten Langerinbinder (IC50 = 300 nM). Die Ligand-PNA-DNA Konstrukte wurden selektiv von Langerin exprimierenden Zellen bei nanomolaren Konzentrationen internalisiert und stellen ein System dar, welches in Zukunft für den Transport von Beladungen Anwendung finden könnte.<br>Targeting the C-type lectin (CTL) langerin has received increasing attention as a novel immunotherapy strategy due to the capacity of Langerhans cells, which express langerin, to endocytose and cross-present antigens to T-cells. Langerin recognizes pathogens such as viruses, which present carbohydrates in a multivalent fashion to increase avidity as the monovalent carbohydrate ligands only display low affinity for langerin. Inspired by nature, multivalency has therefore been a key tool for overcoming the low affinities of CTL-carbohydrate interactions. In contrast to highly multivalent ligand presentation with undefined arrangements this work strove to optimize ligand economy by designing bivalent ligands that take the distance between the binding sites of the homotrimeric langerin into consideration by precise arrangement of ligands on DNA-based scaffolds. Studying the multivalent mechanisms at work led us to the design of ligands that take both statistical rebinding and the chelate effect into account. The rebinding effect was recognized as a tool that not only increases ligand avidity at a single binding site but in addition can be exploited to amplify the chelate effect. This method provides a solution for overcoming the low or non-existing multivalency effects when bivalently presenting low affinity ligands on a rigid scaffold if high affinity ligands are unavailable. A combination of this arrangement strategy with the development of a first langerin selective glycomimetic ligand led to the most potent molecularly defined langerin binder to date (IC50 = 300 nM). The ligand-PNA-DNA constructs were selectively internalized by langerin expressing cells at nanomolar concentrations and constitute a delivery platform for the future transport of cargo to Langerhans cells.
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Azazna, Djamille. "Les bambusurils : molécules-cages pour l'encapsulation d'anions et utilisation comme nouvelles plateformes multivalentes d'intérêt biologique." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS454.
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Les bambusurils, BU[4] et BU[6], sont des oligomères cycliques apparentés aux cucurbiturils, CBs, constitués respectivement de 4 et 6 motifs glycolurils. Les bambusurils diffèrent des CBs par la présence de glycolurils difonctionnalisés.Les BU[6] ont la capacité d'encapsuler des anions dans leur cavité, propriété intéressante pour la décontamination d'effluents, par exemple.Une nouvelle famille de bambusurils, les allylbambusurils, qui possèdent des groupements allyles sur leur portail macrocyclique, a été développée. Leur post-fonctionnalisation par oxydation, métathèse croisée ou réaction thiol-ène a été étudiée. Par réaction thiol-ène, des BU[4] et BU[6], fonctionnalisés respectivement par 8 ou 12 thiols d'intérèt, ont été obtenus. Les BU[6] sont toujours isolés avec un halogènure à l’intérieur de leur cavité. Une méthode utilisant l’hexafluoroantimonate d’argent a été mise au point pour les décomplexer. L'affinité de ces nouveaux BU[6] exempts d'anion, pour différents halogénures, a été évaluée par RMN 1H.Des glycobambusurils ont été synthétisés par réaction thiol-ène en présence de sucres fonctionnalisés par des thiols. Ces glycoBUs donnent accès à des plateformes multivalentes de valence 8 pour les BU[4] et 12 pour les BU[6]. Le pouvoir inhibiteur de ces nouvelles plateformes a été testé sur l'enzyme WaaC, une heptosyltransferase présente dans la paroi bactérienne. Les tests enzymatiques montrent que ces glycobambusurils sont des plateformes multivalentes prometteuses<br>Bambusurils, BU[4] and BU[6] are cyclic oligomers that belong to the cucurbiturils family, CBs, assembled respectively by 4 and 6 glycoluril units. Bambusurils are different from cucurbiturils because of their difunctionalized glycolurils. BU[6] are able to encapsulate anions inside their cavity and this property can be useful for the treatment of effluents.A new family of BUs, the allylbambusurils having allyls groups on their macrocyclic portal, has been developed. Their postfunctionalization by oxidation, cross metathesis and thiol-ene coupling has been studied. BU[4] and BU[6] functionalized by respectively 8 and 12 thiols of interest have been prepared.BU[6] are always obtained with an halide inside the cavity. A method using silver hexafluoroantimonate has been developed to remove this halide. Binding constants of these new empty bambusurils have been determined towards severals halide by 1H NMR.Glycobambusurils have been synthesized by thiol- ene coupling with thiosugars. These glycoBUs can lead to multivalent platforms of valency up to 8 for BU[4] and 12 for BU[6]. Inhibition activity of these new platforms has been tested on WaaC enzyme, an heptosyltransferase found in bacterial cell wall. Enzymatic tests show that these glycobambusurils are promising multivalent platforms
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Arnaud, Julie. "Ingénierie de lectines de valence, topologie et spécificité contrôlées pour la biologie cellulaire et la biotechnologie." Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENV029/document.
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La capacité des lectines à reconnaître spécifiquement des glycoconjugués à la surface de cellules en font des outils de diagnostic biomédical pour les pathologies associées à des changements de glycosylation (inflammation, du cancer ...). De par leur interaction avec les glycosphingolipides, ces protéines peuvent aussi être utilisées pour étudier le trafic membranaire. Toutefois, un nombre réduit de lectines sont actuellement disponibles, limitant leur utilisation dans les biotechnologies et la recherche. Le but de ma thèse est d'une part de concevoir des néo-lectines de valence et topologie contrôlées pour comprendre l'effet de la multivalence sur le mécanisme d'endocytose, et d'autre part de concevoir des lectines de spécificité modulable afin de les utiliser dans la reconnaissance spécifique des cellules tumorales.RSL est une lectine à fucose de la bactérie Ralstonia solanacearum qui a une structure en β-propeller formée par l'association de trois monomères présentant deux sites de liaison très similaires. Cette protéine trimérique et hexavalente a été choisie comme structure de base pour la conception de néolectines. Des RSLs trivalentes ont été produites par mutation d'un acide aminé essentiel pour la stabilisation du fucose. Leur caractérisation a démontré qu'ils avaient perdu la capacité d'invaginer la membrane plasmique. Une protéine de même structure que RSL mais monomérique a été ingénierée, puis une librairie de plus de 13 mutants de valence présentant différentes topologies a été créée. L'analyse de tous les mutants a permis de démontrer que la formation de tubules dans les membranes dépend plus de la distance entre les sites que du nombre de sites.Nous avons ensuite mis au point un protocole de bio-informatique afin de prédire l'orientation et la conformation d'oligosaccharides fucosylés dans les sites de fixation de plusieurs lectines à fucose. Les affinités relatives ont pu être calculées avec une bonne corrélation avec les valeurs expérimentales. La modélisation et la structure cristallographique des complexes entre RSL et les oligosaccharides Lewis X et Sialyl Lewis X indiquent un changement conformationnel du glycanne très inhabituel lors de l'interaction, donnant ainsi des pistes pour la conception de mutants de plus haute spécificité<br>The ability of lectins to specifically recognize glycoconjugates on cell surface makes them excellent biomedical diagnostics tools for diseases associated with glycosylation changes (e.g inflammation, cancer, etc.). Furthermore, because of their interaction with glycosphingolipids, lectins may also be used to study membrane trafficking. However, only small number of lectins are currently available, limiting their use in biotechnology and research. The aim of my thesis was first to develop neolectins with controlled valency and topology to understand the effect of multivalency on the endocytosis mechanism, and second to design lectins with tuned specificity for the recognition of tumor cells.RSL is a fucose binding lectin from the bacterium Ralstonia solanacearum which has a β-propeller structure that is formed by the association of three monomers each having two very similar binding sites. This trimeric and hexavalent protein was chosen as the scaffold structure for the design of neolectins. Trivalent RSLs were created by mutating an amino acid with essential role in fucose binding. Characterization showed that these mutants lost the ability to invaginate the plasma membrane. In addition, monomeric RSL was engineered and a library of more than 13 mutants, with different topologies and valencies, was created. Analysis of these mutants showed that the formation of tubules in the membrane depends mostly on the distance between the sites rather than on the number of sites.Then we developed a bioinformatic protocol to predict the orientation and conformation of fucosylated oligosaccharides in the binding sites of several fucose binding lectins. The relative affinities could be calculated with a good correlation to experimental values. Both the model and the crystal structures of RSL complexed with sialyl Lewis X and Lewis X oligosaccharides indicate a very unusual conformational change of the glycan during the interaction. These studies pave the way for the design of mutants with higher specificity
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Achilli, Silvia. "Production recombinante de récepteurs lectines de type C et identification de ligands sélectif : de nouveaux outils pour la modulation du système immunitaire." Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAV014/document.
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Les lectines de type C (CLRs) sont des récepteurs impliqués dans la reconnaissance d’oligosaccharides et principalement exprimés à la surface des cellules présentatrices d’antigène (APCs) et notamment des cellules dendritiques (DCs), véritable sentinelle de notre système immunitaire. Elles sont impliquées dans la reconnaissance de motifs spécifiques exprimés à la surface d’agents pathogènes et sont capables de stimuler le système immunitaire afin de déclencher une réponse adaptée. Ce rôle crucial joué par les CLRs dans l’équilibre de la réponse immunitaire confère aux interactions CLR/glycane des perspectives d’applications pharmaceutiques. L’objectif à long-terme du projet de recherche dans lequel cette thèse s’intègre consiste à utiliser ces CLRs pour modeler les réponses du système immunitaire. A cette fin, des néoglycoconjugués spécifiques de chaque CLR doivent être développés. Au cours de cette thèse, 9 CLRs ont été produits BDCA2, DC-SIGN, DC-SIGNR, dectin-1, dectin-2, langerin, LSECtin, MCL and Mincle. Différentes stratégies de production ont été testées en parallèle, incluant des techniques d’adressage au périplasme en vue d’obtenir des protéines solubles et fonctionnelles et de l’expression cytoplasmique, sous forme de corps d’inclusion suivie d’étapes de renaturation qui s’est révélé la plus efficace au final. Une stratégie permettant de construire des tétramères artificiels de CLRs, appelés TETRALEC, a été mise au point. Cet outil permettant le criblage et la caractérisation des lectines a été obtenu avec DC-SIGNR par un marquage spécifique de la lectine. Le complexe TETRALEC a été caractérisé au niveau structural et des tests fonctionnels ont été menés sur des puces à glycanes et des cellules pathogènes. La série de CLRs que nous avons produites a été utilisée pour cribler des puces à glycanes et à glycomimétiques. Ces études nous ont permis de mettre en évidence des interactions dépendantes de l’environnement du glycane et d’identifier de nouveaux glycanes ou glycomimétiques spécifiques de certains CLRs. En effet, de manière étonnante, plusieurs des CLRs testés sont capables, pour un glycane donné, de discriminer des isomères de position ouvrant ainsi de nouveaux questionnements sur la signification biologique de cette sélectivité. De plus des glycomimétiques reconnaissant préférentiellement dectin-2 par rapport à DC-SIGN, DCSIGNR et langerin ont été identifiés. Le choix des glycomimétiques et l’évaluation des étapes de leur optimisation ont été permis par diverses études biophysiques qui ont quantifié la force et la spécificité des interactions. Ceci a permis le développement d’un ligand optimisé sélectif de DC-SIGN. La co-cristallisation de la protéine avec ce ligand a révélé un intéressant mode de liaison qui amène également de nouvelles questions. Simultanément à l’optimisation de ligands monovalents, un premier pas a été réalisé vers la conception d’une molécule pour permettre une vaccination contre le cancer médiée par les CLRs. Les résultats de SPR ont identifié des candidats potentiellement intéressants et des tests biologiques préliminaires ont été réalisés<br>C-type Lectin Receptors (CLRs) are carbohydrate-binding proteins mainly expressed on Antigen Presenting Cells (APCs), including dendritic Cells (DCs), the sentinel of the innate immune system. They recognize pathogens or damaged cells by interacting with glycan features and the encounter between the CLR and its ligand constitutes a necessary step for the activation of the adaptive immune system. This crucial role played by CLRs in the balance of immune responses offers to CLR-glycan interactions pharmaceutical applications. The long-term objective of the research project in which this PhD is included is to use these CLRs as modulators in order to tailor the immune system responses. To do so, neoglyco-conjugates selective to each individual CLR have to be developed.Nine different CLRs were produced in this work: BDCA2, DC-SIGN, DC-SIGNR, dectin-1, dectin-2, langerin, LSECtin, MCL and Mincle.Several approaches have been explored in parallel for CLR production, ranking from bacterial periplasmic targeting, aiming to express soluble and functional protein, to inclusion bodies production into the bacterial cytoplasm, with subsequent protein refolding. Our collection of CLRs were used to screen glycan and glycomimetic arrays, highlighting context-dependent binding and identifying natural ligands or glycomimetics selective to each CLRs. Thus, several CLRs were surprisingly able to differentiate between positional isomers of a given N-Glycan, which opens new questions regarding the biological significance. Moreover, glycomimetics with a selectivity towards dectin-2 over DC-SIGN, DC-SIGNR and langerin CLRs have been identified.To guide the choice of the glycomimetics and estimate their optimisation, diverse biophysical studies were performed to evaluate the strength and specificity of the interaction. This enabled the development of an ultimate ligand selective towards DC-SIGN. A co-crystallised structure of the protein with this ligand revealed an interesting binding mode that also opens new questions.Simultaneously to monovalent ligand optimization, a first step towards the design of a highly defined molecule for cancer vaccination by CLR targeting was made. SPR results revealed potential candidates to exploit and preliminary biological assays were performed. Finally, a strategy for tetrameric lectin engineering as been explored, termed TETRALEC. This tool for screening and lectin characterization, has been obtained with one the lectin of the study, DC-SIGNR, by a site-specific labelling of the lectin. The TETRALEC complex was structurally characterised and functional assays were performed on glycan array and pathogen cells
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Bandlow, Victor. "Multivalente Kohlenhydrat-PNA∙DNA-Konjugate zur Charakterisierung von Hämagglutininen und Entwicklung hochpotenter Inhibitoren von Influenza-Viren." Doctoral thesis, Humboldt-Universität zu Berlin, 2021. http://dx.doi.org/10.18452/22398.
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Das Prinzip der Multivalenz ist in der Natur allgegenwärtig, welches auch von Influenza-Viren genutzt wird, um über ihre Oberflächenproteine an epitheliale Wirtszellen zu binden. Diese Interaktion bietet einen interessanten Ansatzpunkt für multivalente Inhibitoren, wenn es gelingt, die Bedingungen für eine effiziente Wechselwirkung mit dem Virus zu entschlüsseln. Hierzu wurde in dieser Arbeit eine Charakterisierung des Hämagglutinin-Trimers (HA) auf viralen Partikeln mittels Kohlenhydrat-Nukleinsäuregerüsten und Kohlenhydrat-Polyethylenglykol (PEG)-Gerüsten vorgenommen. Distanz-Affinitäts-Beziehungen für die Interaktion des trimeren HA mit den bivalenten Präsentationen des Sialyl-LacNAc zeigten, dass bivalente PEG-Konjugate nicht in der Lage sind, eine bivalente Verstärkung der Wechselwirkungen mit der löslichen HA-Ektodomäne oder mit HA auf der viralen Oberfläche herbeizuführen, wobei die räumliche Rasterung mit PNA∙DNA-Gerüsten eine bimodale Distanz-Affinitäts-Beziehung ergab. Ein Affinitätsmaximum in einem Abstand von 52 - 59 Å wurde einer simultanen Bindung an zwei kanonische Bindungsstellen eines HA-Trimers zugeordnet, wobei ein zweites Affinitätsmaximum bei 26 Å auf die Existenz einer sekundären Bindungsstelle hindeutet. In dieser Arbeit wurde erstmals die multivalente Präsentation von Glykoliganden auf langen repetitiven DNA-Templaten demonstriert. Es wurden Nukleinsäure-Komplexe erhalten die eine vollständige Inhibierung der Virus-induzierten Hämagglutination bei einer Konzentration von 10^(-9) M des Templats erzielten, was einer 10^7-fachen Verstärkung bezogen auf den monovalenten Zucker entspricht. Neben einer hochpotenten Inhibition offenbarten distanzoptimierte bivalente und multivalente Binder auf Nukleinsäuregerüsten auch subtypspezifische Inhibition.<br>The principle of multivalency is omnipresent in nature, which is also used by influenza viruses to bind to epithelial host cells via their surface proteins. This interaction offers an interesting starting point for multivalent inhibitors if the conditions for an efficient interaction with the virus can be deciphered. For this purpose, the hemagglutinin trimer (HA) on viral particles was characterized using carbohydrate-nucleic acid scaffolds and carbohydrate-polyethylene glycol (PEG) scaffolds. Distance-affinity relationships for the interaction of the trimeric HA with the bivalent presentations of the sialyl-LacNAc showed that bivalent PEG conjugates are not capable of a bivalent enhancement of the interactions with the soluble HA ectodomain or with HA on the viral surface, whereby the spatial screening with PNA∙DNA scaffolds resulted in a bimodal distance-affinity relationship. An affinity maximum at a distance of 52 - 59 Å was assigned to simultaneous binding to two canonical binding sites of an HA trimer, with a second affinity maximum at 26 Å indicating the existence of a secondary binding site. In this work the multivalent presentation of carbohydrate ligands on long repetitive DNA templates was demonstrated for the first time. Nucleic acid complexes were obtained which achieved a full inhibition of the virus-induced hemagglutination at a concentration of 10^(-9) M of the template, which corresponds to a 10^7-fold increase in relation to the monovalent sugar. In addition to a highly potent inhibition, distance-optimized bivalent and multivalent binders on nucleic acid structures also revealed subtype-specific inhibition.
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Pascal, Yoann. "Dynasweet - Les glycodyn[n]arènes comme ligands multivalents de lectines : une étude par chimie combinatoire dynamique." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSE1288/document.
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De nombreux glycoclusters multivalents des calixarènes, des pillararènes ou des fullerènes ont été synthétisés au sein de notre laboratoire et ont montré d'excellentes affinités pour diverses lectines grâce à leur multivalence et au « glycoside cluster effect ». Nous avons cherché à approfondir ces résultats en ajoutant un degré de dynamisme à ces molécules. Pour cela, nous avons appliqué les concepts de la chimie combinatoire dynamique où des briques moléculaires s'auto-assemblent via des liaisons réversibles pour générer à l'équilibre thermodynamique une chimiothèque d'oligomères. Des briques moléculaires dithiophénols glycosylés sont capables de s'auto-assembler via la formation de ponts disulfures. Leurs propriétés ont été investiguées en chimie combinatoire dynamique et la distribution d'espèces résultant de l'équilibration a montré la formation exclusive des cyclotrimères et cyclotétramères, ou dyn[3]- et dyn[4]arènes. La répétition de l'expérience en présence d'une lectine modèle (ConA) a mené à l'amplification des homodyn[3]- et homodyn[4]arènes. Ces derniers ont été isolés par HPLC semi-préparative et leurs affinités pour ConA ont été mesurées en ITC dans le domaine du nanomolaire. Une extension de cette méthodologie aux lectines LecA et LecB de Pseudomonas aeruginosa est en cours<br>Several glycoclusters based on calixarenes, pillararenes or fullerenes have been synthesized in our laboratory. They exhibited strong affinities for several lectins through their multivalence and the “glycoside cluster effect”. The prupose of this study was to add a dynamic part to these molecules. We therefore applied the concept of dynamic combinatorial chemistry in which building blocks are able to self-assemble through reversible bonds to generate a library of oligomers. Dithiophenols bearing carbohydrate epitopes can self-assemble through the formation and exchange of disulfide bonds. Their properties in dynamic combinatorial chemistry were studied and the species distribution at the thermodynamic equilibrium revealed the selective formation of cyclotrimers and cyclotetramers named dyn[3]- and dyn[4]arenes. The equilibration in the presence of ConA, used as a model lectin, have led to the amplification of homodyn[3]- and homodyn[4]arenes. These glycodyn[n3,4]arenes have been isolated and their affinities toward ConA measured by ITC in the nanomolar range. Extension of this methodology toward the lectins LecA and LecB of Pseudomonas aeruginosa is in progress
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Ligeour, Caroline. "Synthèse de nouveaux glycooligonucléotides et glycoclusters : étude de leurs affinités avec les lectines I et II de Pseudomonas aeruginosa et la lectine de Burkholderia ambifaria." Thesis, Montpellier 2, 2013. http://www.theses.fr/2013MON20211/document.
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Les interactions sucre-lectine jouent un rôle très important dans de nombreux processus biologiques comme les infections par des virus ou des bactéries. Toutefois, ces interactions étant faibles, la présentation de manière multivalente des résidus saccharidiques est nécessaire pour obtenir une augmentation significative des constantes d'association. Une technique basée sur l'utilisation de glycooligonucléotides et d'une puce à ADN utilisée comme plateforme d'ancrage a permis d'étudier l'affinité d'un grand nombre de composés envers les lectines PA-IL et PA-IIL de Pseudomonas aeruginosa et la lectine BambL de Burkholderia ambifaria. Les glycooligonucléotides ont été synthétisés, à partir de blocs de construction synthétisés en aval, en utilisant la chimie des acides nucléiques supportée et automatisée (phosphoramidites et H-phosphonate) ainsi que des réactions de « click chemistry » (la cycloaddition 1,3-dipolaire catalysée par le cuivre (I) ou le couplage thiol par addition de type Michael ou par substitution nucléophile d'un dérivé bromoacetamide).Les glycoclusters ayant montrés une bonne affinité envers les lectines cibles ont été sélectionnés et resynthétisés en solution sans l'étiquette ADN à l'échelle de la centaine de milligrammes. Les glycoclusters ainsi synthétisés en deux ou trois étapes avec une seule purification ont pu être évalués par quatre techniques d'analyse des interactions (HIA, ELLA, SPR et ITC) en présence des lectines PA-IL, PA-IIL et BambL. Nous avons trouvé un tétragalactocluster et un tétrafucocluster possédant une forte affinité envers la lectine PA-IL et BambL respectivement avec des valeurs de Kd de 157 nM et 43 nM<br>Carbohydrate-lectin interactions play a key role in various biological processes such as infection by viruses or bacteria. As these interactions are weak, the multivalent association of carbohydrate is necessary to increase the binding constant. We used glycooligonucleotide and DNA chip to study the affinity of diverse compounds to PA-IL and PA-IIL lectins of Pseudomonas aeruginosa and Bambl lectin of Burkholderia ambifaria. Glycooligonucleotides were synthesized with previously prepared building blocks, using automated supported nucleic acid chemistry (phosphoramidites and H-phosphonate) and “Click chemistry” (copper (I) catalyzed 1,3-dipolar cycloaddition, thiol coupling by Michael addition and nucleophilic substitution of bromoacetamide derivative).Glycoclusters showing the better affinities toward the lectins have been synthesized to a hundred milligrams scale in solution without the DNA tag. The synthesis processes in two or three steps and only one final purification. Their interactions with the lectins PA-IL, PA-IIL and BambL were studied by several assays (HIA, ELLA, SPR and ITC). A tetragalactocluster and a tetrafucocluster showed high affinity toward respectively the lectin PA-IL (Kd = 157 nM) and the lectin BambL (Kd = 43 nM)
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Curk, Tine. "Modelling multivalent interactons." Thesis, University of Cambridge, 2016. https://www.repository.cam.ac.uk/handle/1810/266916.
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A Multivalent entity, which could represent a protein, nanoparticle, polymer, virus or a lipid bilayer, has the ability to form multiple bonds to a substrate. Hence, a multivalent interaction can be strong, even if the individual bonds are weak. However, much more interestingly, multivalency enables the design of highly specific interactions using non-specific individual bonds. We attempt to rationalise multivalent effects using simple physical models complemented with numerical simulations. Based on physiochemical characteristics of multivalent binders, we aim to predict the overall strength of interaction and its sensitivity to variation in parameters. We start with a simple model of homo-multivalency, where all bonds are equivalent. Such systems can exhibit a super-selective response, which denotes the high sensitivity of the strength of multivalent binding to the number of accessible binding sites on the target surface. We present a theoretical analysis of systems of multivalent particles and show that a certain degree of disorder is necessary for super-selective behaviour. Moreover, we formulate a set of simple design rules for multivalent interactions that yield optimal selectivity. In the second stage, we expand the model to hetero-multivalency, accounting for multiple distinct types of binding partners. We consider targeting of cells based on a density profile of different membrane receptors types and demonstrate, that speci city towards a desired receptor density profile can be obtained. Hence, cells can be reliably targeted in the absence of specific markers. Crucially, we show that for optimal selectivity, individual bonds must be weak. Finally, we add information about specific geometry and positions of binding sites on the multivalent entity. We focus on molecular imprinting; the process whereby a polymer matrix is cross-linked in the presence of template molecules. The cross-linking process endows the polymer matrix with a chemical ‘memory’, such that the target molecules can subsequently be recognised by the matrix. We show how the binding multivalency and the polymer material properties affect the efficiency and selectivity of molecular imprinting.
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Padigi, Sudhaprasanna Kumar. "Multivalent Rechargeable Batteries." PDXScholar, 2015. https://pdxscholar.library.pdx.edu/open_access_etds/2464.
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Li+ ion batteries have been the mainstay of high energy storage devices that have revolutionized the operating life time of consumer electronic devices for the past two decades. However, there is a steady increase in demand for energy storage devices with the ability to store more energy and deliver them at high power at low cost, without comprising safety and lifetime.
Li-ion batteries have had significant challenges in increasing the amount of stored energy without affecting the overall lifetime and the ability to deliver stored energy. In order to store and deliver more energy, more lithium ions need to be inserted and extracted from a given electrode (cathode or anode). Upon inserting a large number of Li ions, the crystal lattice of the materials undergo severe mechanical distortions, leading to un-desirable structural changes. This results in underutilization of theoretical energy storage capacities of the electrodes and early failure of the batteries owing to instabilities in the electrode materials.
Unlike monovalent Li+ ions, multivalent rechargeable batteries offer a potential solution to the above problems. Multivalent cations, such as Ca2+, are doubly-ionized as opposed to Li+ which is a monovalent cation. The advantages of using Ca2+ ions instead of Li+ ions are multifold. Due to the doubly-ionized nature, only half the number of Ca2+ ions need to be inserted and extracted from a given electrode to store and deliver energy from a high capacity cathode as compared to Li+ ions. This reduces the probability of lattice distortion and un-desirable structural changes, further leading to increased utilization of high theoretical energy storage capacities of the electrodes (cathode and anode). The use of Ca2+ ions also helps in delivering twice the amount of current density as compared to Li+ ions due to its doubly ionized nature.
In this work, a set of eight metal hexacyanoferrate compounds were synthesized using the following metal ions: Ba2+, Mn2+, Zn2+, Co2+, Fe3+, Al3+, Sn4+, Mo5+. The resulting metal hexacyanoferrate compounds were subjected to physical characterization using scanning electron microscope (SEM) and powder x-ray diffraction (XRD), to determine physical properties such as size, morphology, unit cell symmetry and unit cell parameters. This was followed by electrochemical characterization utilizing cyclic voltammetry and galvanic cycling, to determine the specific capacity and kinetics involved in the transport of Ca2+ ions to store charge. Optical characterization of the metal hexacyanoferrates using Fourier transform infrared (FTIR) spectroscopy, allowed for the identification of metal-nitrogen stretching frequency, which was used as a measure of the strength of the metal-nitrogen bond to understand the role of the above mentioned metal ions in electron density distribution across the unit cell of the metal hexacyanoferrates.
The specific capacity utilization of the metal hexacyanoferrates, when compared to the electronegativity values (Xi) of the above mentioned metal ions, the σ- parameter, and the metal-nitrogen stretching frequency (v), revealed an empirical trend suggesting that the materials (FeHCF, CaCoHCF and CaZnHCF) that possessed intermediates values for the above mentioned parameters demonstrated high capacity utilization (≥50%). Based on these empirical trends, it is hypothesized that a uniform distribution of electron density around a unit cell, as reflected by intermediate values of the electronegativity (Xi) of the above mentioned metal ions, the σ-parameter and the metal-nitrogen stretching frequency (v), results in minimal electrostatic interactions between the intercalating cation and the host unit cell lattice. This results in relatively easy diffusion of the cations, leading to high specific capacity utilization for metal hexacyanoferrate cathodes. These parameters may be used to select high efficiency cathode materials for multivalent batteries.
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Reiter-Scherer, Valentin D. "Multivalency in the interaction of biological polymers." Doctoral thesis, Humboldt-Universität zu Berlin, 2020. http://dx.doi.org/10.18452/21711.
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Diese Dissertation konzentriert sich auf die Untersuchung multivalenter Wechselwirkungen zwischen Hämagglutinin (HA) sowie Neuraminidase (NA) zweier Stämme des Influenzavirus (H1N1 und H3N2) und dem zellulären Liganden Sialinsäure (SA) unter Verwendung von Rasterkraftmikroskopie und Einzelmolekülkraftspektroskopie (SMFS). Bindungskräfte sowie Dissoziations- und Assoziationskinetiken, zusammen mit den intermolekularen Potentiallandschaften wurden, nach bestem Wissen erstmalig, auf Einzelmolekülebene mittels SMFS quantifiziert. Zu diesem Zweck wurden mono- und multivalente SA-Liganden (SAPEGLA und dPGSA) eingesetzt. Abweichungen der experimentellen Kraftspektren vom klassischen Kramers-Bell-Evans-Modell vorhergesagten Verhalten wurden durch das Friddle-Noy-De Yoreo-Model berücksichtigt. NA beider Virusstämme zeigte trotz ähnlicher Bindungskräfte eine stabilere Bindung mit SA als HA und dissoziierte 3 – 7 mal langsamer. Es wird vermutet, dass die höhere Stabilität die geringere Oberflächendichte von NA auf der Virushülle im Vergleich zu HA ausgleicht. Die Bindungskräfte eines SAPEGLA-Clusters nehmen mit der Anzahl der Bindungen und die Dissoziationskinetik folgt dem theoretisch vorhergesagten Trend. Die Dissoziationsrate von NA ist etwa 6-mal höher ist als ihre katalytische Rate, weshalb Mehrfachbindungen zur Spaltung von SA erforderlich sind. Die Dissoziationsrate von N1 in der gleichen Größenordnung wie die von H3 und es wird vermutet, dass derartige Ähnlichkeiten die Übertragbarkeit des Virus begünstigen. Darüber hinaus wird gezeigt, dass die thermische Stabilität von HA-dPGSA höher ist als von HA-SAPEGLA und im Bereich von 3 - 4 Einzelbindungen liegt, was für NA-dPGSA nicht beobachtet werden konnte. Daher bindet dPGSA spezifisch und kooperativ multivalent an HA. Kompetitive Bindungstests zeigen, dass SMFS zum Screening von antiviralen Inhibitoren verwendet werden und Zugang zu deren Design auf Einzelmolekülebene liefern könnte.<br>This thesis focuses on studying multivalent interactions between influenza virus hemagglutinin (HA) as well
as neuraminidase (NA) of two viral strains (H1N1 and H3N2) and the cellular ligand sialic acid (SA) by using scanning force microscopy and single molecule force spectroscopy (SMFS). Unbinding forces as well as dissociation and association kinetics together with the free energy landscapes were, to the best knowledge for the first time, individually quantified on the single molecule level using SMFS.
To this extent, designed synthetic monovalent (SAPEGLA) and multivalent (dPGSA) SA displaying ligands were employed. Surprisingly, the experimental force spectra did not show the log-linear trend predicted by the classical Kramers-Bell-Evans model, but rather follow the more recent Friddle-Noy-De Yoreo model. NA of both viral strains forms a more stable bond with SA than HA, and dissociates 3 to 7 times slower. It is reasoned that the higher stability compensates for the lesser amount of NA compared to HA that is typically found on the viral envelope. The unbinding forces of the cluster of SAPEGLA increased gradually with the number of bonds in the cluster and the dissociation kinetics follow the theoretically predicted trend.
The dissociation rate of NA was found to be about 6 times higher than its catalytic rate, indicating that multiple bonds are needed for cleavage of SA. The dissociation rate of N1 is on the same order as that of H3, suggesting that these similarities between the two strains favor transmissibility. The thermal stability of the HA-dPGSA bond is higher than the HA-SAPEGLA reaching that of three to four single bonds, proving specificity and cooperativity. Such an enhancement could not be observed for the binding of NA. This thesis also shows that SMFS could be used as a tool to screen antiviral inhibitors in competitive binding assays, which may contribute insight into the design of antiviral inhibitors on the single molecule level.
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Bueno, Robison Poreli Moura. "Um estudo multivalente do Trio de Alberto Nepomuceno." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/27/27157/tde-12032019-113458/.
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Este trabalho aborda analiticamente o Trio em fá sustenido menor (1916) do compositor brasileiro Alberto Nepomuceno, com objetivo de constituir um estudo de caso que permita um melhor posicionamento da obra do compositor no período de transição entre o romantismo e o modernismo brasileiros. Ele levanta dados do contexto ideológico-musical no qual se insere a obra, em especial das noções francesas de progresso e suas consequências musicais no início do século XX. A pesquisa apresenta também os fundamentos teóricos de uma proposta analítica que visa incorporar à análise estrutural os desdobramentos do significado musical. Ela procura unir, por meio do conceito de multivalência, os estudos das tópicas, dos esquemas, da narratividade e da intertextualidade. O trabalho apresenta quatro análises multivalentes, uma para cada movimento da obra. Os resultados apontam para uma obra que se constitui em uma rede de símbolos musicais introversivos e extroversivos, que faz um equilíbrio entre a tradição formal e expressiva e o uso de novos materiais sonoros.<br>This work analyzes the Piano Trio in F sharp minor by the Brazilian composer Alberto Nepomuceno, aiming to constitute a case study that allows a better positioning of the composer\'s work in the period of transition between Brazilian romanticism and modernism. It raises data from the ideological-musical context in which the work is inserted, especially the French notions of progress and its musical consequences in the early twentieth century. The research also presents the theoretical foundations of an analytical proposal that aims to incorporate into the structural analysis the unfolding of musical meaning. It seeks to unite, through the concept of multivalence, the studies of topics, schemata, narrativity and intertextuality. The work presents four multivalent analysis, one for each movement of the work. The results point to a work that constitutes a network of introversive and extroversive musical symbols, which makes a balance between formal and expressive tradition and the use of new sound materials.
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Cobo, Cardenete Isidro Felipe. "Glycolipids: synthesis and multivalent systems." Doctoral thesis, Universitat Rovira i Virgili, 2012. http://hdl.handle.net/10803/284152.
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Els glicolípids i particularment els glicoesfingolípids són compostos d’interès perquè poden interaccionar amb biofactors tot inhibint o interferint en processos fisiològics de les cèl•lules. Per exemple, els glicoesfingolípids que recobreixen les membranes cel•lulars poden interaccionar en processos de reconeixement amb bactèries, virus i toxines com per exemple la toxina del Còlera la qual inicia el procés d’infecció pel reconeixement de glicolípids com el GM1. Tot i que l’ús d’antibiòtics és el tractament més emprat, la resistència als antibiòtics a zones endèmiques fa necessària la recerca en síntesi d’inhibidors basats en derivats de carbohidrats. Donat que la síntesi de compostos glicoconjugats que presenten multivalència ha resultat competitiva en la preparació d’inhibidors contra patògens en aquest treball s’ha estudiat la síntesi de nous mimètics basats en -galactosilceramides; l’acoblament Sukuki-Miyaura en 2-iodoglicals per obtenir nous precursors de carbohidrats i l’anclat de -galactosilceramides en suports com polímers hiperramificats per tal d’avaluar la seva inhibició front la toxina del Còlera.<br>Los glicolípidos y particularmente los glicoesfingolípidos son compuestos de interés porque pueden interaccionar con biofactores inhibiendo o interfiriendo en procesos fisiológicos de las células. Por ejemplo, los glicoesfingolípidos que recubren las membranas celulares pueden interaccionar en procesos de reconocimiento con bacterias, virus y toxinas como por ejemplo la toxina del Cólera la cual inicia el proceso de infección a través del reconocimiento de glicolípidos como el GM1. Aunque el uso de antibióticos es el tratamiento más empleado, la resistencia a los antibióticos en zonas endémicas hace necesaria la investigación en síntesis de inhibidores basados en derivados de carbohidratos. Dado que la síntesis de compuestos glicoconjugados que presentan multivalencia ha resultado competitiva en la preparación de inhibidores contra patógenos, en este trabajo se ha estudiado la síntesis de nuevos miméticos basados en -galactosilceramidas; el acoplamiento Sukuki-Miyaura en 2-yodoglicales para obtener nuevos precursores de carbohidratos y el anclado de -galactosilceramidas en suportes como polímeros hiperramificados con el fin de avaluar su inhibición frente la toxina del Cólera.<br>Glycolipids such as glycosphingolipids are interesting compounds because they can interact with biofactors by inhibiting or interfering in physiological processes on cells.
For instance, the glycolipids which present on cellular membranes can interact with bacteria, virus and toxins. In deed, Cholera toxin starts its infective process once it has recognized glycolipids such as GM1. Although the use of antibiotics is the commonest treatment against this disease, the antibiotic resistance in endemic areas makes the investigation in the synthesis of inhibitors based on carbohydrate derivatives necessary.
Due to the synthesis of multivalent glycoconjugated compounds have been competitive in order to prepare inhibitors against these pathogens, in the present work we have studied: the synthesis of new mimetics based on -galactosylceramides; the Suzuki-Miyaura cross coupling in 2-iodoglycals in order to obtain new carbohydrate precursors and the anchoring of -galactosylceramides in scaffolds such as hyperbranched polymers in order to evaluate their inhibition binding against to Cholera toxin
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Hughes, P. J. "Multivalent ligand recognition by pentraxins." Thesis, University College London (University of London), 2016. http://discovery.ucl.ac.uk/1473766/.
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The pentraxins, serum amyloid P component (SAP) and C-reactive protein (CRP) are target proteins for the development of treatments for amyloidosis and ischaemic injury, respectively, in humans. This study reports the first multivalent ligands capable of targeting all five SAP binding sites simultaneously. Ligands presenting five or ten D-proline headgroups and composed of five peptideglycol linkers emanating from ε-N-substituted lysine residues on a central cyclic peptide core were synthesised by solid phase peptide synthesis. The sub-nanomolar, ~250pM, binding affinity approximated by Isothermal Titration Calorimetry (ITC) for one decavalent ligand is the strongest affinity for an SAP binding ligand currently known and stronger than the affinity of SAP binding to amyloid deposits. X-ray crystallography and mass spectrometry shows the decavalent ligands noncovalently cross-linking two SAP pentamers, in the same manner observed for lead drug candidate CPHPC, but with increased affinity. In addition, the binding of SAP with N-acetyl D-proline has been investigated by x-ray crystallography. Using a 1.5Å resolution structure the exact interaction of the headgroup used in CPHPC, penta- and decavalent ligands, was investigated. The results show potential for an electrostatic interaction between the carbonyl oxygen of acetyl from the ligand and the side chain amide of Gln148, which has not previously been considered. Applications of multivalent binding are still emerging; in this study, bivalent ligand BPC8 was used as an additive to crystallise CRP from the Rat (rCRP) in non-covalently cross-linked decameric complexes. Previous x-ray crystallography studies have failed due to extreme radiation sensitivity of the crystals produced. This problem has been overcome with a complete dataset obtained from a single crystal at 3.2Å. No inter-protein contacts are seen between pentamers in the decamer complex, therefore the use of bivalent ligands has facilitated the observed crystal packing. Multivalent ligands are suggested as tools for overcoming difficult crystallisation issues.
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Bromfield, Stephen M. "Multivalent heparin binding and sensing." Thesis, University of York, 2014. http://etheses.whiterose.ac.uk/7943/.
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Heparin therapy involves the clinical use of heparin as an anti-coagulant, for example, during surgery. At the conclusion of treatment, systemic heparin levels must be quantified to allow accurate dosing of a heparin antidote. This thesis details work towards a better sensing methodology and an improved antidote. A synthetically-simple arginine-functionalized dye – Mallard Blue (MalB) – was synthesised and shown able to detect heparin across a clinically relevant concentration range in biological media such as human serum. The heparin binding of MalB is selective over structurally related glycosaminoglycans and is highly tolerant of electrolytic competition. Indeed, the performance of MalB is comparable with the best heparin sensors currently known and makes it the new best-in-class thionine dye. Mallard Blue was developed into a straightforward competition assay able to report on the relative heparin binding efficiencies of candidate molecules in competitive media, including human serum. Using this assay in conjunction with molecular dynamics modelling techniques, fundamental insights into the binding of poly(amidoamine) (PAMAM) dendrimers to heparin were gained. Interestingly, the medium sized (G2-G4) dendrimers achieved the most charge-efficient heparin binding. Comparisons against derivatives modified with poly(phenylenevinylene) cores revealed native PAMAMs to be exponents of adaptive multivalency, in contrast to the more rigid derivatives’ shape-persistent multivalency. The performance of self-assembled multivalent (SAMul) heparin binder C22G1DAPMA was studied in different biological media and shown to be more charge-efficient than the currently used heparin antidote under competitive conditions. Also, C22G1DAPMA was able to reverse anti-coagulation in heparinized human plasma and degrade on a clinically interesting timescale. Structural modifications afforded two new families of SAMul binders, which unveiled fundamental differences in the chiral preferences of heparin and DNA, along with probing the effects of nanoscale morphology on heparin binding ability and aggregate-stability in serum.
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Mehta, Mary Anne. "Multivalent ions in polymer electrolytes." Thesis, University of St Andrews, 1993. http://hdl.handle.net/10023/15517.
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The electrochemical, thermal and structural properties of polyethylene oxide (PEO) based polymer electrolytes containing multivalent ions were investigated. The phase diagram for the PEO:Ca(CF3SO3)2 system was determined by x-ray diffraction and differential scanning calorimetry techniques. Precipitation of the salt from the system at high temperatures was directly observed by variable temperature x- ray diffraction. This was ascribed to a negative entropy of dissolution of the salt in the polymer. A new crystalline complex PEO6Ca(CF3SO3)2, which exhibits a phase transition between two polymorphic forms was observed. The temperature dependence of ionic conductivity was related to the phase diagram. Redox behaviour of the PEO:Nil2 system was probed. Motion of the Ni(II) species through the system was extremely slow as evidenced by the low effective diffusion coefficient (1.82 x 10 11 cm 2s−1) and cationic current fraction (F+ < 0.1). Deposition of nickel from the polymer was characterised by instantaneous nucleation followed by three dimensional diffusion controlled growth. Investigation of the redox behaviour of the PE0:Eu(CF3SO3)3 system indicated that reduction of Eu3+ followed an ec mechanism. Evidence was obtained for extremely slow diffusion of Eu3+ containing species (D[sub]eff ~ 3.66 x 10 −16cm2s−1) through the system and slow kinetics of electron transfer. Thermal studies of the PEO:Co(SCN)2 system indicated that the glass transition temperature (Tg) was grossly elevated by the presence of Co(SCN)2 in the polymer. The absence of a crystalline PEO:Co(SCN)2 complex was ascribed to the high Tg which leads to slow crystallisation kinetics. UV-visible spectra indicated that the Co2+ ion was tetrahedrally coordinated in the system at low salt concentrations. The structure of the PEO3NaClO4 crystalline complex was reported as a subsidiary study.
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Brument, Sami. "Ligands multivalents pour l'interaction par effet chélate avec les récepteurs nicotiniques et les lectines AFL et DC-SIGN." Thesis, Nantes, 2016. http://www.theses.fr/2016NANT4029.
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Les reconnaissances cellulaires sont souvent promues par des interactions multiples et simultanées entre des ligands et leurs récepteurs spécifiques. Ce principe de multivalence a inspiré la communauté scientifique pour accroitre l’affinité d’un ligand synthétique son récepteur. Différents effets de multivalence ont été identifiés parmi lesquels l’effet chélate basé sur l’interaction simultanée d’un ligand avec plusieurs sites de reconnaissance d’une protéine. Nous avons développé durant cette thèse trois séries ligands multivalents pour obtenir un effet chélate avec trois cibles : les récepteurs nicotiniques et les lectines AFL et DC-SIGN. Aspergillus fumigatus est un pathogène adhérant aux récepteurs fucosylés via la lectine hexavalente AFL. Nous avons développé des fucosides di-, hexa- et polyvalent dont les affinités pour AFL ont été évaluées par microcalorimétrie et par test cellulaire. Cela nous a permis d’identifier un ligand hexavalent capable d’inhiber l’adhésion cellulaire des spores d’ A. fumigatus à des concentrations micromolaires. DC-SIGN est une lectine tétramérique reconnaissant les motifs mannose et utilisée comme voie d’entrée infectieuse par le cytomégalovirus. Plusieurs structures à faible et haute valence (2, 4 et 89) de mannose nous ont permis d’obtenir des composés très affins pour cette lectine avec des IC50 de l’ordre du nanomolaire lors de tests d’adhésion cellulaire. Enfin, nous avons développé des séries de composés multivalents pour l’interaction avec les récepteurs nicotiniques pour une application potentielle aux maladies neurodégénératives. Ces ligands ont montré des propriétés antagonistes de l’acétylcholine sur des récepteurs de type α7<br>Cell recognitions are often promoted by multiple and simultaneous interactions between ligands and their specific receptors. This concept of multivalency has inspired the scientific community to increase the affinity of a synthetic ligand for his receptor. Various effects of multivalency have been identified, including the chelate binding mode based on the simultaneous interactions of a ligand with several binding sites of a protein. During this thesis, we have developed three families of multivalent structures to reach a chelate binding mode with three proteins: the nicotinic receptors and the DCSIGN and AFL lectins. Aspergillus fumigatus is a pathogen adhering to the fucosylated receptors through the hexavalent lectin AFL. We have developed di-, hexa and polyvalent fucosides whose affinities for AFL were evaluated by microcalorimetry and cellular assays. We identified a hexavalent ligand able to inhibit the cell adhesion of A. fumigatus spores at micromolar concentrations. DC-SIGN is a tetrameric lectin binding to mannose units, used in an infectious pathway by the cytomegalovirus. Several structures at low and high valency (2, 4 and 89) of mannose allowed us to reach high affinity for this lectin with IC50 in nanomolar range in the cell adhesion tests. Finally, we developed a series of multivalent compounds to interact with the nicotinic receptors for an application in neurodegenerative diseases. These ligands have shown antagonist properties on acetylcholine α7 type receptor
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Chekkat, Neïla. "Etude de stratégies innovantes pour augmenter l'efficacité antitumorale de ligands synthétiques de TRAIL-R2 et CD40." Thesis, Strasbourg, 2014. http://www.theses.fr/2014STRAJ043/document.
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TRAIL (TNF-Related Apoptosis Inducing Ligand) et CD40 Ligand, membre de la superfamille (SF) du TNF (Tumor Necrosis Factor) apparaissent comme des cibles attractives pour la thérapie ciblée du cancer. Une caractéristique commune des membres de la SF-TNF est la structure homotrimérique du ligand qui oligomérise les récepteurs pour induire la signalisation cellulaire. Cette interaction multivalente entre ligands et récepteurs est déterminante dans l’induction de la réponse cellulaire. L’objectif de cette thèse est de i) développer des ligands multivalents de TRAIL-R2 et CD40 afin d’améliorer leur efficacité anti-tumorale puis de les associer dans des stratégies anti-tumorales innovantes et ii) de caractériser les interactions entre ces ligands et les récepteurs à la surface de la cellule pour comprendre l’impact de l’oligomerisation sur l’initiation de l’apoptose au niveau membranaire.Ainsi nous avons utilisé des peptides cycliques spécifiques du récepteur de TRAIL-R2 (TRAILmim/DR5) que nous avons multimérisés sur des plateformes chimiques innovantes. Nous nous sommes également intéressés à l’état d’oligomérisation des récepteurs avant leur contact avec le ligand dans le but de mieux comprendre les interactions multivalentes. Enfin, nous avons caractérisé à l’aide de la technique de résonance plasmonique de surface et d’un biocapteur basé sur la fluorescence les interactions entre ces ligands multivalents et le récepteur TRAIL-R2. Ces travaux nous ont donc montré la nécessité d’analyser les interactions entre ligands et récepteurs directement à la surface de la cellule pour améliorer le développement de ligands pro apoptotiques efficaces<br>TRAIL (TNF- Related Apoptosis Inducing Ligand) and CD40Ligand, members of the superfamily (SF) of TNF (Tumor Necrosis Factor), appear as attractive targets for cancer therapy. A common feature of members of the TNF-SF is the homotrimeric structure that oligomerized their receptors to induce cell signaling. This multivalent interaction between ligands and receptors is crucial for apoptosis induction.The aims of this thesis is to i) develop multivalent ligands of TRAIL -R2 and CD40 to enhance their antitumor efficacy and to associate them in innovative strategies and ii) to characterize the interactions between ligands and receptors at cell surface to understand the impact of oligomerization on the initiation of apoptosis at membrane level.We used cyclic peptides specific of TRAIL-R2 (TRAILmim/DR5) that we multimerized on innovative chemical scaffolds. We also interested in the state of receptor oligomerization before their contact with the ligand in order to better understand the multivalent interactions. Finally, we characterized using the technique of surface plasmon resonance and biosensor based fluorescence interactions between multivalent ligands and TRAIL- R2.In this work we showed the need to analyze the interactions between ligands and receptors directly on the surface of the cell to improve the development of effective pro -apoptotic ligands
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Stein, Benjamin [Verfasser]. "Multivalente Ligandenhüllen kolloidaler Nanopartikel / Benjamin Stein." Berlin : Freie Universität Berlin, 2014. http://d-nb.info/1054328951/34.
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Kanfar, Nasreddine. "Synthèse d'inhibiteurs multivalents des anhydrases carboniques." Thesis, Montpellier, 2017. http://www.theses.fr/2017MONTT197/document.
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Les anhydrases carboniques (CA, CE. 4.2.1.1) sont des métalloenzymes de zinc, ubiquitaires, qui catalysent l'hydratation réversible du CO2, avec la formation de bicarbonate et de la libération d'un proton. Sur les 13 isoformes actifs présents chez l'homme, certains d'entre eux sont impliqués dans les processus pathologiques. Les CA sont connues depuis plus de 50 ans en tant que cibles thérapeutiques et certains inhibiteurs sont actuellement en phase clinique ou dans des études pré-cliniques pour le traitement du glaucome, de l'épilepsie et de cancer. Néanmoins, le manque de sélectivité contre les différents isoformes responsables des effets secondaires nécessite le développement de nouvelles stratégies. Le but de ce travail est de développer une nouvelle façon pour inhiber les CAs en tirant parti de l'interaction multivalente pour inhiber sélectivement et efficacement les isoformes de l'CA. En effet, les clusters multivalents représentent une classe émergente de composés pour l'inhibition d'enzymes. Cette stratégie a été développée récemment pour l'inhibition et l'activation d'CA, certaines études ayant démontré des améliorations dans la puissance d'inhibition et la sélectivité. Dans ce projet, différentes plateformes (peptides, nanoparticules de silice) multifonctionnels ont été revêtus de sulfonamides comme inhibiteurs de l'CA par bioconjugaison. L'effet d'inhibition et la spécificité de la multivalence ont été étudiés sur les isoformes CA<br>Carbonic anhydrases (CAs, EC. 4.2.1.1) are ubiquitous zinc metalloenzymes which catalyze the reversible hydration of CO2 with formation of bicarbonate and release of a proton. On the 13 active isoforms present in human, some of them are involved in pathological processes. CAs are known for more than 50 years as a therapeutic targets, and some inhibitors are currently in clinic or in (pre)clinical studies for the treatment of glaucoma, epilepsy and cancer. Nevertheless the lack of selectivity against the different isoforms responsible of side-effects requires the development of new strategies. The aim of this work is to develop a new way for CA inhibition by taking advantage of multivalent interaction to selectively and efficiently inhibit CA isoforms. Indeed, multivalent clusters represent an emerging class of compounds for enzymes inhibition. This strategy has been recently developed for CA inhibition and activation, some studies reporting improvements in inhibitory potency and selectivity. In this project, different platforms (peptides, polymers, silica nanoparticles) multifunctional were coated with sulfonamides as inhibitors of CA by bioconjugation. The inhibitory effect and specificity of the multivalency were studied isoforms CA
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Porkolab, Vanessa. "Développement de ligands multivalents de nature glycomimétiques dirigés contre les récepteurs lectines de type-C." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAV013/document.
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Les composantes innée et acquise de l'immunité travaillent ensemble pour assurer une protection efficace de l'organisme. Les cellules dendritiques, cellules sentinelles de l’immunité capturent via des récepteurs de surface les agents pathogènes et les présentent aux lymphocytes T pour stimuler les réponses immunitaires adaptatives spécifiques. Une famille de ces récepteurs, nommée Récepteurs Lectines de type C (CLRs) ont un rôle important dans la reconnaissance de motifs oligosaccharides des pathogènes. Leurs fonctions sont parfois détournées par certains pathogènes à leur avantage et notamment le VIH. La reconnaissance du virus par DC-SIGN, une des CLRs, favorise la dissémination du virus. A l’inverse, la langerine, autre CLR, est considérée comme une barrière naturelle au VIH. Ainsi, DC-SIGN est devenue une cible thérapeutique prometteuse mais sa reconnaissance des ligands osidiques est largement partagée par la langerine.Ce travail vise à développer des antagonistes de DC-SIGN spécifiques et de hautes affinités permettant de rivaliser avec la présentation multivalente des glycosylations de gp120 du VIH avec DC-SIGN. Une approche rationnelle a été employée dans le développement de ligands glycomimétiques hautement sélectifs pour DC-SIGN à partir de l’étude du site de liaison des deux CLRs. Puis, des plates-formes de présentations de ces glycomimétiques, de valences et de géométries différentes, sont comparées par SPR. Les améliorations spectaculaires d'affinités parfois observées sont liées à différents mécanismes d’interactions multivalentes responsables d’un phénomène d’avidité.Sur une des architecture de présentation sélectionnée (RODs), un travail de caractérisation fine des mécanismes responsables de ce gain d’affinité et/ou d’avidité a été conduit par la combinaison de plusieurs techniques biophysiques (SPR, ITC, polarisation de fluorescence et AUC). L’influence de la topologie de cette structure sur les mécanismes d’interactions est ainsi mise en évidence. Par les travaux menés, plusieurs ligands multivalents ont montré des affinités sans précédent pour DC SIGN atteignant des affinités du nanomolaire et représentant les meilleurs inhibiteurs connus à ce jour.Associé au développement d’antagonistes multivalents, une CLR (DCIR) a été identifiée récemment comme impliquée dans la dissémination du VIH, comme DC¬SIGN. Dans une perspective future de développement de glycomimétique, des travaux ont été menés sur la caractérisation structurale et fonctionnelle de ce nouvel acteur dans la problématique VIH<br>The innate and acquired immunity components work together to provide efficient protection of organisms. Dendritic cells, sentinel cells of the immunity, are able to capture pathogens through their receptors on the surface and they can present the antigens to lymphocytes T in order to stimulate specific adaptive immune responses. Among these receptors, there is a family named C-type lectin receptors (CLRs), which has an important role in the recognition of pathogenic oligosaccharide motifs. CLRs can be hijacked by many pathogens including HIV. DC-SIGN, one of the CLRs, interacts with the virus and promotes its dissemination. Unlike DC-SIGN, langerin, another CLR, has a protective role against the HIV infection. In this context, DC-SIGN became a promising therapeutic target but it shares ligand specificities with langerin.This work aims to develop highly specific antagonists against DC-SIGN in order to compete with the multivalent glycosylated gp120 protein of HIV. Using the study of the two lectins binding sites as starting point, a rational approach has been exploited to develop highly selective glycomimetics against DC SIGN. The SPR technique was used to investigate multivalent platforms with different valencies as well as ligand presentation in space. The amazing improvement of the affinity observed in some cases can be linked to different mechanisms of multivalent interactions, leading to an avidity phenomenon. On a selected scaffold (RODs), we characterized the different mechanisms responsible for the affinity and/or avidity gains, using a combination of different biophysical techniques (SPR, ITC, fluorescence polarization, AUC). In this work, we highlighted that the topology of this structure can influence the mechanisms of interactions. Overall, different multivalent ligands showed unique affinities for DC-SIGN, reaching the nanomolar affinity range, and they represent the best inhibitors to date.Finally, another CLR has been recently identified as one of the protein involved in the HIV infection as well as DC-SIGN. In a future perspective of glycomimetic development, structural and functional characterization has been done on this new actor involved in the HIV issue
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Sieben, Christian. "Host cell invasion by influenza A virus." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2013. http://dx.doi.org/10.18452/16743.
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Influenzaviren müssen in die Wirtszelle aufgenommen werden, um dort ihr Genom freizusetzen und ihre Replikation mit Hilfe des Reproduktionsapparats der Zelle einzuleiten. Der komplexe Replikationszyklus der Influenza A Viren ist noch nicht vollständig verstanden. Er beginnt mit der Bindung des viralen Hämagglutinins (HA) an Sialinsäure (SA) auf der Zelloberfläche der Wirtszelle. In dieser Arbeit wurde die Virusbindung an Zellen mit unterschiedlicher Rezeptorkomposition verglichen. Dabei konnte gezeigt werden, dass für die zelluläre Spezifität die Präsentation des Rezeptors innerhalb der Plasmamembran der Zelle eine größere Rolle spielt als die Struktur des Rezeptorglykans selbst. Des Weiteren deuten die Beobachtung sehr kleiner Kräfte und ein stufenweises Öffnen von Bindungen auf eine multivalente Interaktion hin. Multivalenz wird oft in biologischen Bindungsprozessen beobachtet und kann Bindungskräfte enorm verstärken. Basierend auf diesen Ergebnissen wurden inhibitorische Nanopartikel entwickelt, die die natürliche Zelloberfläche als hochaffine Bindungsalternative imitieren. Verschiedenartige Nanopartikel wurden evaluiert und konnten die Virusaktivität um mehr als 80 % hemmen. Nach der Bindung wird das Virus durch Endozytose in die Zelle aufgenommen. Durch spezifische Virusmarkierung und gleichzeitiger Expression von zellulären Markerproteinen wurde der Transport einzelner Viren in lebenden Zellen verfolgt. Dabei konnte gezeigt werden, dass das Virus sowohl durch frühe, als auch durch späte Endosomen wandern muss, um sein Genom erfolgreich in das Zytoplasma zu entlassen. Außerdem verzögert das Virus die endosomale Ansäuerung um eine optimale Aufenthaltsdauer im Endosom und die lokalisierte Fusion in der Nähe des Zellkerns zu gewährleisten. Pharmakologisches Eingreifen in diese Prozesse konnte zudem weitere kritische Faktoren identifizieren, die die Effizienz der Virusinfektion stark beeinflussen.<br>Influenza virus must enter a host cell to deliver its genome, use the cells reproductive machinery and eventually initiate its replication. The replication cycle of influenza A virus is very complex and still not fully understood. It generally starts with binding of the viral protein hemagglutinin (HA) to its cellular receptor sialic acid (SA). In this work, virus-cell attachment forces were investigated at the single molecule level using intact virus binding to living cells, a set-up that closely mimics the in vivo situation. Cells of different surface SA composition were compared. It could be shown that the unique presentation of the ligand within the cells plasma membrane, rather than the structure of the receptor-glycan itself, strongly affects cellular specificity. The low binding forces as well as the observation of stepwise unbinding events suggest a multivalent interaction type. Based on this finding, inhibitory nanoparticles mimicking the cell surface were constructed. Different particles were evaluated and shown to efficiently inhibit virus infection by ≥ 80 %. Since many molecular details of multivalent interactions remain poorly understood parameters such as ligand spacing and presentation were varied and revealed that the density of ligands as well as the interacting surface plays critical roles for virus inhibition. Upon attachment, the virus enters the cell by endocytosis. Virus trafficking was followed at the single-virus level in living cells. The kinetics of virus transport were visualized using fluorescent marker proteins in combination with specific virus labeling. It was found that the virus needs to progress through early and late endosomal compartments in order to efficiently uncoat and release its genome. Further, the virus delays the endosomal acidification to ensure optimal residence time and fusion in the region close to the host cell nucleus. Drug treatment furthermore unraveled critical factors influencing viral infection efficiency.
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Alali, Urjwan. "Chemical synthesis of multivalent chemical probes and their study as modulators of multivalent glycan-protein interactions." Thesis, Amiens, 2018. http://www.theses.fr/2018AMIE0002.
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Le présent travail vise à étudier le comportement des nanoparticules d'or décorées par des glycooligosaccharides vis-à-vis de l'action hydrolytique de la glycosidase notamment inhibitrice de ces enzymes. La première partie de cette étude visait à synthétiser des molécules qui miment des composés naturels capables de moduler diverses interactions spécifiques de liaison glucides - lectines. Dans un deuxième temps, la synthèse de dérivés de cyclodextrines comme alternative extrêmement flexible pour construire des conjugués multivalents a été réalisée. Des entités oligosaccharidiques ont été greffées de manière covalente à des positions spécifiques des cyclodextrines. Une réaction chimique de Huisgen, plus précisément une cyclo- addition d'azide-alcyne catalysée par un ion Cu+ [CUAAC] a été réalisée ici. Ces réactions ont été optimisées en utilisant des conditions micro-ondes pour préparer une bibliothèque de α, β, γ- cyclodextrines perglycosylées qui ont montré une efficacité enzymatique vis-à-vis de certaines enzymes<br>The present work seeks to investigate the behaviour of glyco- gold nanoparticle towards the hydrolytic action of glycosidase regarding these mutivalenty glyco nanostructures as glycosidase inhibitors. The first part of this study aimed to synthesi simulated vehicles that mimic natural compounds to modulate various specifi carbohydrate – lectin binding interactions. Secondly, synthesis of cyclodextrin specie that showed to be an exceedingly flexible delineation to build multivalent conjugate when the covalent attachment of biodetected sugar entities at specific positions o cyclodextrin were grafted. Click chemistry reaction using cuporous ion – catalyze azide- alkyne cyclo-addition reaction [CUAAC] has been performed herein. To justify the full homogeneinity of our adducts, these reactions have been optimized usin microwave conditions to prepare a library of perglycosylated α , β , γ cyclodextrin that showed an enzymatic effectiveness towards certain enzymes
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McKelvie, Nicola D. "The development of multivalent Salmonella vaccines." Thesis, University of Newcastle Upon Tyne, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.327267.
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Pei, Xue Yuan. "Structural study of multivalent antibody fragments." Thesis, University of Cambridge, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.310912.
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Yilmaz, Gokhan. "Synthesis of glycomaterials for multivalent interactions." Thesis, University of Warwick, 2016. http://wrap.warwick.ac.uk/89300/.
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Carbohydrates have attracted much attention to insert their biological properties into nanostructured materials due to their use for bio-mimetic purposes, their crucial role in bio-recognition processes at molecular level and their functional role in living systems. Glycopolymers, which are synthetic macromolecules with sugar moieties, exhibit a crucial role for many biological processes such as signal transmission, intercellular recognition and fertilization. The interaction between carbohydrates and lectins could be greatly enhanced by the multivalent effect of densely packed carbohydrate molecules with unique functionalities, which is known as the “glycocluster effect”. Therefore, the investigation of this specific interaction between glycopolymer and protein is very important to create more complex and biologically relevant carbohydrate mimics. Well-defined amphiphilic block glycopolymers with the same mannose content have been self-assembled in aqueous solution to form glyconanoparticles with different morphologies (spherical, worm-like micelles and vesicles). The size and shape of nanoparticles have significant effects on the binding affinities with dendritic cell-specific intercellular adhesion molecule-3-grabbing non-integrin (DCSIGN). Moreover, the obtained glyco-micelles have a great potential for drug delivery applications. Glycopolymer-coated gold nanoparticles (glyco-AuNPs) which were synthesized with reversible addition-fragmentation chain transfer (RAFT) polymerization were combined with doxorubicin (DOX) as a model anticancer drug by creating a pHsensitive hydrazone linkage in the presence of cysteine (Cys) and a cross-linker for both chemotherapy and radiation therapy. The reversible single-chain glycopolymer folding structures in α-shape with different sugar moieties were created to investigate the influence of this folded collapse on the binding capability with different lectins. The single-chain folding structures were achieved by the host-quest interaction of β-cyclodextrin and adamantane in very high diluted aqueous solution. The binding results evidenced that these single-chain folded structures enhanced greatly the multivalent interaction. A new S-glucosyl substituted 2-oxazoline glycomonomer was synthesized via thiolene “click” chemistry and then polymerized using cationic ring-opening polymerization (CROP) technique. In order to investigate the effect of S-glucosyl substituent linker length on the cloud point and binding ability systematically, A series of well-defined glyco-copolymers with different sugar linker length to the polymer backbone was prepared. The obtained results showed that it has a significant influence on the cloud point and binding capability.
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Bartolami, Eline. "Ingénierie et auto-assemblage de systèmes biomoléculaires multivalents." Thesis, Montpellier, Ecole nationale supérieure de chimie, 2015. http://www.theses.fr/2015ENCM0017.
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Les systèmes naturels ont montré l'intérêt de la multiplication des interactions pour une cible, permettant d'améliorer l'affinité et de moduler la spécificité de reconnaissance. Il est ainsi important pour des applications biologiques de concevoir des systèmes multivalents et biocompatibles. Le travail entreprit au cours de ce doctorat porte sur le développement de nouvelles méthodologies pour accéder à des systèmes multivalents originaux.Ainsi, nous avons conçu, par synthèse multi-étapes, une nouvelle plate-forme fonctionnalisée, basée sur un châssis α-PNA pour la reconnaissance multivalente d'oligonucléotides. Ce nouveau système peut potentiellement être impliqué dans la reconnaissance sélective multipoint d'ADN.En parallèle, nous avons préparé des clusters multivalents d'iminosucres sur des châssis peptidiques, construits à partir de ligations click sans métaux, pour l'inhibition enzymatique de glycosidases. En effet, des systèmes multivalents ont été récemment développés en tant qu'inhibiteurs de glycosidases. Cependant, leur méthodologie de synthèse repose quasiment exclusivement sur la ligation azoture-alcyne catalysée au cuivre, ce qui limite son application biologique en raison de sa toxicité. Nos travaux ont ainsi conduit à l'identification d'inhibiteurs efficaces d'α-mannosidases par une approche synthétique sans métaux.Dans le contexte de la vectorisation d'oligonucléotides, il existe un besoin de concevoir des systèmes dynamiques qui permettent un relargage contrôlé. Nous avons appliqué une stratégie d'auto-assemblage, par ligation click de type acylhydrazone, pour la génération in situ de clusters biomoléculaires à partir de châssis peptidiques et de ligands d'acides aminés modifiés. Etant donné le caractère dynamique de la ligation qui confère une adaptabilité au système, nous avons démontré que a) la présence d'une cible permet d'assister la formation des clusters par sélection de certains composants et b) l'ADN peut être relargué par échange de ligands. Cette technique efficace et rapide d'auto-assemblage de fragments a ensuite permis de réaliser un criblage pour sonder l'effet de l'architecture et de la valence sur la complexation. Ce projet a finalement conduit à l'identification de vecteurs efficace pour la transfection de siARN sur cellules.Enfin, dans un dernier projet, nous avons exploité diverses techniques orthogonales et chimiosélectives de ligations click dans le but de générer des nanostructures peptidiques. Deux cages ont ainsi été obtenues par la formation de ligations acylhydrazones et thiol-maléimides selon une approche one-pot.En résumé, ces travaux d'ingénierie et d'auto-assemblage de systèmes biomoléculaires multivalent ont permis le développement de méthodes innovantes pour répondre à des besoins d'actualité et permettre la construction de systèmes multivalents destinés à la reconnaissance d'oligonucléotides, la vectorisation et l'inhibition enzymatique<br>Natural systems are inspiring in showing that the combination of multiple interactions enables improvement in binding affinity and selectivity for a target. Thus, the design of synthetic and biocompatible multivalent systems is of great importance for biological applications. The work described in this PhD thesis aims at developing novel methodologies for generating functional multivalent systems.In order to engineer multivalent systems for the recognition of oligonucleotides, we elaborated a multi-step synthesis of functionalized α-PNA scaffolds bearing side-groups. This new scaffold can potentially serve for the multi-point sequence-selective recognition of DNA.Multivalent nanoconstructs are emerging tools for enzyme inhibition. In this context, we prepared multivalent clusters of iminosugars – by metal-free click ligations on peptide scaffolds – as candidates for glycosidases inhibition. Although such enzyme inhibitors based on iminosugar clusters were recently reported, their synthesis relies almost exclusively on copper-catalyzed azide-alkyne cycloaddition, which notorious toxicity represents a serious limitation for biological applications. Our approach demonstrates that iminosugar clusters can be prepared in a metal-free fashion and exhibit strong multivalent effects for the inhibition of α-mannosidases. Multivalent biomolecular systems are also candidates for gene delivery application. In this context, the design of dynamic systems is of interest for achieving controlled release. We implemented a self-assembly strategy, using the acylhydrazone click ligation, for the in situ generation of biomolecular clusters starting from peptide scaffolds and modified amino acids building blocks. We showed that, whereas both compounds are ineffective for DNA complexation, the mixed system spontaneously expresses cationic clusters that effectively complex DNA. We further demonstrated that, given the dynamic character of the acylhydrazone ligation, the system is able to a) adapt to the presence of the DNA target by selecting the optimal building blocks for the cluster self-assembly, and b) trigger DNA release by component exchange. This modular and versatile self-assembly approach was further exploited to perform a fragments screening varying molecular structure and valency. Thereby, we identified new and effective vectors for the transfection of siRNA in living cells.The last project described in this manuscript deals with the generation of cage-type peptide nanoconstructs by using a set of orthogonal and chemoselective click ligations. Two cages, based on acylhydrazone ligation on one side and thiol-maleimide on the other, were obtained successfully in one-pot.In summary, this work has led to the development of novel methodologies for the engineering and self-assembly of multivalent biomolecular nanoconstructs for diverse biological applications such as oligonucleotide recognition, delivery and enzyme inhibition
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Klenk, Simon. "Engineered Neoglycoproteins as Tools to Study Biologically Relevant Multivalent Interactions." Doctoral thesis, Humboldt-Universität zu Berlin, 2019. http://dx.doi.org/10.18452/19658.
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In der vorliegenden Arbeit diente das Kapsid der Bakteriophage Qbeta als multivalentes Gerüst und ermöglichte die Bildung eines monodispersen multivalenten Systems, welches mit Homopropargylglycin als unnatürliche Aminosäure modifiziert wurde. Das so eingeführte Alkin ermöglichte kupferkatalysierte Alkin-Azid-Cycloaddition zur Anbindung von Sialinsäuregrupen. Die entsprechende Synthese der hierzu kompatiblen Azid-modifizierten Sialinsäurederivate war eine der Hauptaufgaben dieser Arbeit. Zu diesem Zweck wurde das einfach zugängliche 5-N-Acetyladamantanylthiosialosid als Glykosylierungsdonor in der alpha-selektiven Synthese von Sialosiden evaluiert. Eine effiziente Aktivierung dieses Donors wurde unter optimierten Bedingungen bei -78°C mit N-Iodsuccinimid und Trifluormethansulfonsäure erreicht, was zu hohen alpha-Selektivitäten und Gesamtausbeuten der gewünschten Sialoside führte. Insbesondere Azidoethylenglykol-verknüpfte Sialinsäuren wurden synthetisiert, die für nachfolgende Biokonjugationsreaktionen an das Qbeta-Kapsid verwendet wurden. Die so dargestellten Sialinsäure-modifizierten Qbeta-Kapsidpartikel wurden dann eingehend mit Hilfe mehrerer biophysikalischer und biologischer Tests hinsichtlich ihrer Fähigkeit an Hämagglutinin zu binden und eine Influenza-Infektion zu inhibieren charakterisiert. Niedrige nanomolare Affinitäten wurden in diesen Assays gemessen. Eine sehr effiziente Infektionshemmung in vergleichbaren Konzentrationsbereichen konnte in einem in vitro Zell-, sowie einem in vivo Maus- als auch einem menschlichen ex vivo Modellsystem beobachtet werden. Verschiedene pathologisch relevante Influenzastämme konnten über die hier vorgestellte Strategie ebenfalls gebunden werden. Die monodisperse und definierte Struktur des Qbeta-Gerüsts erlaubte es außerdem ein theoretisches Modell der zugrundeliegenden Bindungsmodi zu erstellen.<br>In this thesis, the bacteriophage Qbeta capsid served as a multivalent scaffold and facilitated the generation of a monodisperse multivalent system which was modified with homopropargylglycine as an unnatural amino acid. The introduced alkyne enabled copper-catalyzed alkyne-azide cycloaddition to attach sialic acid groups. The corresponding synthesis of the compatible azide-modified sialic acid derivatives was one of the main tasks of this work. For this purpose, the straightforwardly accessible 5-N-acetyladamantanyl thiosialoside was evaluated as a glycosylation donor in the alpha-selective synthesis of sialosides. Efficient activation of this donor was achieved under optimized conditions at -78°C with N-iodosuccinimide and trifluoromethanesulfonic acid which led to high alpha selectivities and overall yields of the desired sialosides. Particularly azidoethylene glycol-linked sialic acids were synthesized which were used for subsequent bioconjugation reactions to the Qbeta capsid. These synthesized sialic acid-modified Qbeta capsid particles were then thoroughly characterized by multiple biophysical and biological assays regarding their ability to bind to hemagglutinin and to inhibit influenza infection. Low nanomolar affinities were measured in these assays. A very efficient infection inhibition in a comparable concentration range was observed in in vitro cellular, in vivo mouse and ex vivo human model systems. Several pathologically relevant influenza strains could also be bound with the strategy presented here. The monodisperse and defined structure of the Qbeta scaffold additionally allowed for the establishment of a theoretical model describing the underlying binding modes.
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Duan, Haohao. "Polymères à activités biologiques : nanoparticules et multivalence." Thesis, Bordeaux, 2016. http://www.theses.fr/2016BORD0114.
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Les nanoparticules à base d’acide hyaluronique (AH) sont utilisées pour de nombreuses applications pharmaceutiques. Elles peuvent cibler les tumeurs par interaction avec le CD44,qui est un récepteur biologique surexprimé à la surface de certaines cellules cancéreuses. Dans ce projet nous explorons l’application potentielle de ces nanoparticules dans les domaines cosmétiques, car l’AH est aussi un ingrédient important pour l’hydratation et le renouvellement de la peau. Les copolymères à bloc à base de polypeptides et de polysaccharides ont été synthétisés par une combinaison de polymérisation par ouverture de cycle et de couplage par chimie « click ». Les nanoparticules ont été obtenues par l’auto assemblage de ces copolymères en utilisant un procédé de nano precipitation, dont la taille et la morphologie sont contrôlées par les paramètres expérimentaux. L’interaction entre les nanoparticules d’AH et le CD44 a été quantifiée par la résonance de plasmon de surface(RPS). En comparant avec l’AH libre en solution, les nanoparticules d’AH ont montré une interaction plus efficace avec le CD44, mettant ainsi en évidence un effet de multivalence des nanoparticules. Finalement, la dégradation enzymatique de ces nanoparticules d’AH a été évaluée avec deux types de hyaluronidases, HYAL1 et SPAM-1. La digestion des nanoparticules de l’AH a été significativement ralentie par rapport à l’AH libre. De manière très surprenante, ces nanoparticules de AH ont pu inhiber l’activité de l’enzyme HYAL1 et protéger l’AH libre dans la solution. Enfin, des ligands du récepteur TLR2 de type lipopeptide ont été synthétisés et leurs performances via TLR2 ont été évaluées par RPS<br>Nanoparticles based on hyaluronic acid (HA) are widely used in pharmaceutics. They can target the tumor by the interaction with CD44, a biological receptor overexpressed in some cancer cells. In this project, we investigate the potential applications of these nanoparticles in cosmetics, since HA is also an important ingredient for the skin hydration and renewing. Block copolymers based on polypeptides and polysaccharides were synthesized using a combination of ring opening polymerization and “click chemistry”. The nanoparticles were formed by the self-assembly of these block copolymers using a nanoprecipitation process, and their size and morphology were controlled by the experimental conditions. The interaction between nanoparticles and CD44 were measured by surface plasmon resonance(SPR). Compared to free hyaluronic acid chains in solution, the HA-based nanoparticles could interact more efficiently with CD44, thus demonstrating a multivalent effect. The enzymatic degradation of these HA nanoparticles was then evaluated with twohyaluronidases: HYAL1 and SPAM-1. The digestion of the HA nanoparticles was significantly slower than that of free hyaluronic acid. Surprisingly, these HA nanoparticles could even inhibit the activity of the enzyme HYAL1 and protect free HA chains in the solution. Finally, lipopeptide-based ligands of the biological receptor TLR2 were also synthesized and their performances were evaluated by SPR
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Vukojicic, Petar. "Affitin-dendrimer conjugates for multivalency-enhanced targeting." Thesis, Nantes, 2019. http://www.theses.fr/2019NANT1002/document.
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Les nanoparticules décorées de ligands de ciblage sont des dispositifs puissants développés pour servir d'outils théranostiques efficaces contre des maladies graves comme le cancer ou les maladies infectieuses. En raison des limitations importantes des anticorps en tant que ligands de ciblage, comme une grande taille et une faible stabilité, les protéines d'affinité modifiées à façon offrent une alternative intéressante pour la fonctionnalisation des nanoparticules. Les Affitines sont de petites protéines thermiquement et chimiquement stables, dérivées d'une famille de protéines d’archées de 7 kDa liant l'ADN, dont la spécificité et l'affinité pour leurs cibles sont comparables à celles des anticorps. Les dendrimères de l'acide gallique-triéthylèneglycol (GATG) sont des macromolécules monodispersées, synthétiques, globulaires, en forme d'arbre, préparées de façon itérative (générations) permettant une présentation multivalente des ligands de ciblage. L'objectif de ce travail de thèse est de combiner les propriétés de ciblage des Affitines et la polyvalence des dendrimères pour obtenir des conjugués Affitines-dendrimères pour des applications biomédicales. Le premier objectif était de mettre au point une méthode de conjugaison orientée pour incorporer des Affitines ciblant Staphylococcus aureus (S. aureus) et un traceur fluorescent pour la détection et l'imagerie, puis de les caractériser en termes de taille, d’hétérogénéité, de composition et d’affinité. Le deuxième objectif était d'évaluer leur potentiel à moduler des comportements multicellulaires complexes, comme l'agglutination et la formation de biofilms de S. aureus grâce aux interactions multivalentes implémentées<br>Smart targeted nanoparticles are powerful devices developed to serve as efficient theranostic tools against severe disorders such as cancer or infectious diseases. Due to important limitations of antibodies as targeting ligands, such as large size and low stability, engineered affinity binding proteins offer an attractive alternative for nanoparticle functionalization. Affitins are small, thermally and chemically stable proteins derived from an archaeal 7 kDa DNA-binding family, with specificity and affinity for their targets comparable to that of antibodies. Gallic acid-triethylene glycol (GATG) dendrimers are monodisperse, synthetic globular tree-like macromolecules prepared in a stepwise fashion (generations) allowing multivalent presentation of targeting ligands. The aim of this project is to combine the targeting properties of Affitins and the versatility and multivalency of dendrimers to obtain Affitin-dendrimer conjugates for biomedical applications. The first goal of this work was to develop a site-specific conjugation method to incorporate Affitins targeting Staphylococcus aureus (S. aureus) and a fluorescent dye for detection and imaging, and then to thoroughly characterize them in terms of size, heterogeneity, composition and affinity. The second goal was to assess the potential of these conjugates to modulate complex multicellular behaviors, such as agglutination and biofilm formation of S. aureus due to enhanced multivalent interactions
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Scheibe, Christian. "Multivalente Präsentation von Kohlenhydraten via PNA•DNA-Hybridisierung." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2012. http://dx.doi.org/10.18452/16639.
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Die Wechselwirkung zwischen Kohlenhydraten und Lektinen ist relativ schwach. Dennoch ist sie in einer Fülle biologischer Prozesse von essentieller Bedeutung. Eine Verstärkung der Bindungsaffinität wird häufig durch Multivalenz, d. h. die Ausbildung mehrerer Bindungen zwischen zwei Bindungspartnern, realisiert. Neben der reinen Anzahl der präsentierten Liganden spielt jedoch auch deren Positionierung im Raum eine große Rolle. In dieser Arbeit wurde ein molekulares Lineal entwickelt, das einen modular aufgebauten PNA/DNA-Duplex als Gerüst nutzt und die Präsentation von Liganden im Raum mit atomarer Auflösung ermöglicht. Die Anzahl der präsentierten Liganden, der Abstand zwischen diesen und die Flexibilität des Gerüsts, das diese verbindet, können einerseits fein moduliert werden und sind andererseits sehr gut vorhersagbar. Mittels diverser Bindungsassays wurde zunächst gezeigt, dass das Werkzeug für die räumliche Rasterung von Kohlenhydrat-Lektin-Wechselwirkungen geeignet ist. Die ermittelten räumlichen Anordnungen der Bindungstaschen von Erythrina cristagalli Lektin (ECL) und Ricinus communis Agglutinin (RCA120) waren in Übereinstimmung mit den Kristallstrukturanalysen. Im Fall von RCA120 wurde neben den primären Bindungstaschen zudem eine potentielle sekundäre Bindungstasche identifiziert. Anschließend wurde das Werkzeug für die räumliche Rasterung eines weniger gut charakterisierten Systems verwendet. Im Detail handelte es sich um die Wechselwirkung zwischen Selektinen und seinen Liganden wie sie während der Leukozytenadhäsionskaskade infolge einer Entzündung auftritt. Als Liganden wurden das natürliche Tetrasaccharid Sialyl-Lewis-X und ein artifizielles DNA-Aptamer präsentiert. Dabei zeigte sich, dass der Abstand zwischen zwei bivalent präsentierten Liganden nur einen geringen Einfluss auf die Bindungsaffinität hatte. Die Selektin-Moleküle besaßen demnach eine hohe Flexibilität und/oder waren nicht absolut starr in der Membran verankert.<br>The interaction between carbohydrates and lectins is relatively weak. Still, it is of great importance in a plethora of biological processes. An enhancement of the binding affinity is often achieved via multivalency, i.e., the formation of several bonds between two binding partners. Besides the number of presented ligands, their spatial alignment is crucial as well. In this study, a molecular ruler was developed that utilizes a modularly assembled PNA/DNA duplex as scaffold and allows the presentation of ligands in space with atomic resolution. The number of presented ligands, the distance between them, and the flexibility of the scaffold that connects them can be nicely modulated and, at the same time, are very well predictable. By using various binding assays it was first shown that this tool is suitable for the spatial screening of carbohydrate-lectin interactions. The determined spatial alignments of the binding sites of Erythrina cristagalli lectin (ECL) und Ricinus communis agglutinin (RCA120) were in agreement with the crystal structure analyses. In addition to the primary binding sites, a potential secondary binding site was identified in the case of RCA120. Afterwards, the tool was used for the spatial screening of a system that is less well characterized. In detail, this was the interaction between selectin and its ligands as it occurs during the leukocyte adhesion cascade as a result of an inflammation. The natural tetrasaccharide sialyl-Lewis-X as well as an artificial DNA aptamer were presented as ligands. It was found that the distance between two bivalently presented ligands had only a minor effect on the binding affinity. Accordingly, the selectin molecules had a high flexibility and/or were not absolutely rigid anchored in the membrane.
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Brissonnet, Yoan. "Développements d'iminosucres multivalents et étude de leurs affinités sur les glycosidases." Nantes, 2014. https://archive.bu.univ-nantes.fr/pollux/show/show?id=8fe4cd22-9aed-4531-89d3-669ca2a3b220.
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Malgré les efforts de recherche importants consentis pour le développement d’inhibiteurs de glycosidases, très peu de molécules ont atteint le stade de médicaments. Ce constat s’explique aisément par la complexité d’avoir un inhibiteur qui possède à la fois une affinité importante mais également une sélectivité envers une seule et unique cible. Récemment, la possibilité d’accroitre considérablement ces deux paramètres a été rapportée grâce à la conception d’inhibiteurs multivalents. L’objectif de ce travail de thèse a été de développer des iminosucres multivalents dont certains paramètres structuraux varient, comme la topologie des ligands ou la valence, afin d’étudier les aspects fondamentaux qui régissent les interactions multivalentes dans l’inhibition de glycosidases. La synthèse de ligands à faible valence (inférieure ou égale à 8) mais de structuration spatiale contrôlée, nous a tout d’abord permis d’observer une amélioration importante d’affinité, qui est dépendante de la distribution spatiale des iminosucres. Nous avons également obtenu une sélectivité accrue envers Jbman. De plus, un effet multivalent a aussi été observé sur une mannosidase d’intérêt biologique de la famille GH38. Des analyses AFM ont permis de montrer la formation d’agrégats, confirmé par DLS, qui pourraient expliquer les augmentations d’affinité observées. Ensuite, la synthèse de différents ligands multivalents, à base de déoxynojirimycine et déoxymannojirimycine, de très haute valence, comprise entre 20 et 900, a été effectuée afin de déterminer l’influence de la valence dans l’inhibition des glycosidases. Les évaluations biologiques effectuées sur cinq glycosidases, mono et oligomériques, ont permis d’identifier deux enzymes sensibles aux effets multivalents, Jbman et l’-L-fucosidase de thermotoga maritima. Durant ces tests, un comportement particulièrement intéressant d’accélération de la catalyse enzymatique a pu être observé sur trois enzymes, démontrant ainsi que ces composés ultravalents peuvent aussi jouer le rôle d’activateurs enzymatiques<br>Despite significant research efforts made for the development of monovalent glycosidases inhibitors, few molecules reached the markets. This fact is easily explained by the complexity to obtain an inhibitor which possesses both a strong affinity and selectivity toward the targeted glycosidase. Recently, the possibility to significantly increase these two parameters was shown with multivalent glycosidase inhibitors. The aim of the thesis has been to develop multivalent iminosugars displaying various structural parameters, such as ligand’s topology or valence, in order to study fundamental aspects governing multivalents interactions for the inhibition of glycosidases. The synthesis of low valency ligands (≤ 8) with controlled topology, allowed us to observe a strong increase of affinity and selectivity with -mannosidase from Jack bean (Jbman). Interestingly, a multivalent effect was also observed with a biologically relevant mannosidase from the GH 38 family. AFM and DLS analysis showed the formation of aggregates which potentially explain the increased affinity. Finally, the synthesis of ligands with much higher valencies (between 20 and 900), based on deoxynojirimycin and deoxymannojirimycin was perform to determine the influence of the valency on the affinity towards specific glycosidases. The biological assays made on five glycosidases, mono and oligomerics, allowed used to identify a new enzyme sensitive to multivalency, the alpha-L-fucosidase from thermotoga maritima. During these tests, we observed an increased enzymatic catalysis on three enzymes, demonstrating that ultravalents compounds can also play the role of enzymatic activators, and therefor moduling enzymatic activity
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Neranon, Kitjanit. "Synthesis and Applications of Dynamic Multivalent Nanostructures." Doctoral thesis, KTH, Organisk kemi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-177280.
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This thesis focuses on the design, synthesis and development of dynamic multivalent nanostructures such as supramolecular dendrimers, liposomes and gold-functionalized nanostructures. These structures can be used for drug delivery and molecular sensing applications. This thesis is divided into three parts: In part one, a general introduction to self-assembly, dynamic systems, metalligand exchange, nanostructured dendritic scaffolds, liposomes and gold nanostructures is given. In part two, a microwave approach is presented as an efficient method for the regioselective deuteration of bipyridine scaffolds. Dynamic systems based on transition metal-bipyridine coordination complexes were investigated. The compositional self-adaptation and kinetics of these dynamic systems were successfully assessed by ESI-MS. Based on this amphiphilic dendrimers/metallodendrimers were also designed and synthesized via a convergent strategy. Their ability to self-assemble into supramolecular assemblies and their controlled disassembly was effectively demonstrated. In part three, two types of drug delivery systems based on dynamic multivalent nanostructures of glycodendrimers/metalloglycodendrimers and drugpresenting liposomes were developed. The dynamic self-assembly of these architectures into supramolecular nanostructures with site-specific functionality through interacting carbohydrate or cholesterol moieties was assessed. The host-guest interaction/encapsulation and controlled release with external stimuli were studied using a fluorescent probe, as well as selected drug molecules. The antibacterial property of the drug delivery systems was also evaluated, demonstrating an enhanced bactericidal activity. A new, rapid and simple approach for the functionalization of plasmonic gold nanostructured surfaces was also developed. The optical performance and light-specific sensitivity of the fluorescent probe on the resulting nanostructures were also presented.<br><p>QC 20151119</p>
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Laigre, Eugénie. "Conception, synthèse et étude de modules de reconnaissance multivalents pour des anticorps." Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAV038/document.
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En dépit d’importants progrès dans le domaine de la thérapie anti-cancéreuse, les traitements actuels restent controversés, notamment en raison de la quantité importante d'effets secondaires induits. L'immunothérapie ciblée a récemment émergée en tant qu'alternative, afin d'améliorer les modalités de traitement des patients atteints du cancer. Malgré tout, seul un nombre limité d’approches sont aujourd’hui disponibles, et une grande partie des problèmes demeurent actuellement sans solution. C'est dans ce contexte que nous nous sommes intéressés à la conception de structures biomoléculaires innovantes et bifonctionnelles, capables de rediriger des anticorps endogènes, présents naturellement dans la circulation sanguine de l'homme, contre les tumeurs et, ce, sans immunisation préalable. Les anticorps naturels circulant étant polyspécifiques et ayant la capacité d’interagir avec des antigènes glycosylés, nous nous sommes plus particulièrement concentrés sur la conception de glycoconjugués multivalents, ligands d’anticorps endogènes. Une première partie de notre étude a consisté à synthétiser différents glycodendrimères multivalents, reposant sur des châssis peptidiques et obtenus par ligations chimiosélectives, tout en variant la nature du motif glycosylé et des plateformes, ainsi que la valence du conjugué. Puis, dans un second temps, des tests d’interaction par biopuce ont été mis en place avec une lectine modèle, la lectine Helix Pomatia Agglutinin (HPA). Des protocoles expérimentaux visant à calculer des constantes de dissociation de surface, ainsi que des IC50 ont été mis en place, permettant d’identifier de bons ligands de HPA avec des affinités de l’ordre du nanomolaire. Les tests par biopuce ont ensuite été confirmés avec d’autres méthodes d’analyses (BLI, ELLA). Finalement, afin d'identifier des architectures tri-dimensionnelles permettant une affinité optimale avec des anticorps, les tests d’interaction ont été adaptés au criblage de séra humains. Un large panel de glycoconjugués a alors été criblé par biopuce avec une vingtaine de séra, permettant la détermination de structures glycosylés prometteuses, qui pourront par la suite être utilisées dans le cadre de notre approche anti-cancéreuse<br>Despite significant progress in anti-cancer therapy, current treatments are still controversial due to numerous side effects. Targeted immunotherapy recently emerged as an ideal alternative to improve treatment modalities for cancer patients. However, very limited approaches are available today and major issues remain to be addressed. In this context, we are interested in the design of biomolecular structures, innovative and bifunctional, able to hijack endogenous antibodies - which are naturally present in the human blood stream - toward cancer cells without pre-immunisation. Since natural circulating antibodies are polyspecific and have the ability to interact with multiple carbohydrate antigens, we focused on the design of multivalent glycodendrimers, as ligands for endogenous antibodies. The first part of our study consisted in synthesizing several multivalent glycoconjugates, based on peptide scaffolds and obtained by chemoselective ligations. To evaluate their influence on antibodies, the nature of both the carbohydrate and the scaffold, and the valency were varied. Then, in a second part of the study, microarray assays were developed with a model lectin, the Helix Pomatia Agglutinin (HPA). Experimental procedures were designed to determine surface dissociation constant and IC50 values, leading to the identification of high affinity ligands for HPA in the nanomolar range. Microarray assays were confirmed by other analytical methods (BLI, ELLA). Finally, the assays on slides were adapted to human sera screening, in order to identify tridimensional architectures highly affine to sera antibodies. A large panel of glycoconjugates were screened by microarray with around twenty sera, leading to the determination of promising glycosylated structures, as antibody ligands. The latter could be subsequently used for our anti-cancer approach
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Lauster, Daniel. "Entwicklung multivalenter Inhibitoren des Eintritts von Influenzaviren in Wirtszellen." Doctoral thesis, Humboldt-Universität zu Berlin, 2018. http://dx.doi.org/10.18452/18802.
Full textAbstract:
Das Influenza A Virus (IAV) stellt weltweit eine ernstzunehmende Bedrohung für Gesundheit und Wirtschaft der Menschheit dar. Ein universeller und langanhaltender Impfstoff konnte noch nicht entwickelt werden und klinisch zugelassene Medikamente verlieren durch die rasante Entstehung von resistenten Stämmen zunehmend ihre Wirkung. Aus diesem Grund gewinnt die Erforschung neuer antiviraler Strategien zur Bekämpfung des Influenzavirus an Bedeutung zum Schutze unserer Gesellschaft.
Eine vielversprechende Zielstruktur für die Entwicklung neuer antiviraler Medikamente stellt das virale Hämagglutinin (HA) dar. Das HA liegt in hoher Dichte auf Influenzaviren vor und ermöglicht die Bindung an Sialinsäuren (SA) auf Wirtszellen und die Verschmelzung mit deren Lipidmembran. HA-bindende Moleküle entfalten eine hemmende Wirkung bereits bei dem ersten Kontakt mit Zellen, sodass eine Infektion erst gar nicht stattfinden kann. Aufgrund einer hohen HA-Dichte auf der Virusoberfläche eignen sich besonders multivalente SA tragende Nanopartikel für die Hemmung einer viralen Infektion.
Aufbauend auf diesen Erkenntnissen, wurden in der vorliegenden Arbeit neue multivalente Binder gegenüber dem viralen Hämagglutinin (HA) entwickelt und studiert. Im Gegensatz zu bereits bekannten multivalenten Sialosiden, die in einer undefinierten räumlichen Orientierung auf Polymergerüsten präsentiert wurden, konnten in der vorliegenden Arbeit strukturelle Aspekte identifiziert werden, um Gerüstsysteme mit optimaler Rezeptorpräsentation gegenüber der Influenza A Virusoberfläche zu generieren.
Neben SA-basierten Polymersystemen wurde auch ein gegen HA gerichtetes Peptid aus einem Antikörper identifiziert, welches sich auch für eine multivalente Interaktion mit IAV eignet.
Diese Arbeit ermöglicht neue Einblicke in die Auswahl geeigneter Trägersysteme, eines optimalen Rezeptorabstandes und der Verwendung alternativer Rezeptoren mit dem Ziel einer Infektionshemmung von IAV.<br>Influenza A virus (IAV) still poses a serious threat to global health and economy of mankind. So far, a universal, long-lasting vaccine could not be developed, and clinically approved drugs are prone to lose activity due to the fast development of resistant strains. Because of this, research on new antiviral compounds and strategies to combat influenza viruses is of great importance for the protection of our society.
A promising candidate for the development of novel antiviral drugs is the viral hemagglutinin (HA) protein. HA is present at high density on the viral envelope, which allows binding to sialic acid (SA) molecules on host cells and fusion with their membrane. Following, HA binding molecules have an inhibitory effect at the very first step of the infection cycle, leading to the inability of an infection. Based on a high HA density on the viral surface, SA carrying nanoparticles qualify for the inhibition of a viral infection.
Based on this knowledge the study at hand demonstrates the development of new multivalent binders against viral HA and discusses them critically.
In contrast to published multivalent sialosides, which are displayed in an undefined fashion on polymer scaffolds, the results of this thesis support the identification of structural requirements for the design of new scaffold systems with an optimal match to the viral surface.
Beside sialoside based polymer systems, completely new peptide based systems, based on an HA binding antibody, were developed. Similar to polyglycerolsialosides, such multivalent peptide-decorated polymers were able to achieve nanomolar binding inhibition constants, too.
In summary, this thesis enables new insights into the choice of a suitable carrier system, the optimal receptor spacing, and the use of alternative receptors with the ultimate goal of virus neutralization.
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Reeh, Philipp. "Dynamic Multivalency For The Recognition Of Protein Surfaces." Doctoral thesis, Universitat Rovira i Virgili, 2014. http://hdl.handle.net/10803/283236.
Full textAbstract:
En esta tesis doctoral el concepto de multivalencia en el reconocimiento de proteínas (lectinas) con azúcares se combinó con la idea de la química dinámica combinatoria. Esto se aplicó, no sólo para sacar ventaja del efecto de la mejor afinidad de tales sistemas multivalentes, sino también para dotar al sistema con una mayor variedad de constituciones y geometrías. La determinación de las afinidades relativas de los miembros de la biblioteca dinámica dio una visión de los requisitos necesarios para la unión entre azúcares – lectina.
El primer enfoque para acceder a los sistemas multivalentes para el reconocimiento de lectinas (presentado en el capítulo 2 de la tesis), está basado en estrategias bien conocidas. Enlaces covalentes reversibles son usados para acceder a bibliotecas dinámicas combinatorias (DCLs). En esta parte del trabajo se confirmó la viabilidad del procedimiento analítico elegido. Especies diméricas, similares a las que se había conocido desde experimentos de otros grupos, mostraban buena analisabilidad de los DCLs formados. El método analítico elegido (HPLC MS) permitió la detección de las afinidades y selectividades relativas de tales constituyentes de la respectiva biblioteca. Para la elaboración de las bibliotecas dinámicas, varios intentos fueron realizados basados en el mismo concepto: Una subunidad central con múltiples puntos de conexión para favorecer interacciones reversibles.
Formación de una librería dinámica basada en un conector central.
Específicamente, se evaluaron los puentes di sulfuro y la formación de imina. Algunos de estos estudios resultaron ser complicados por problemas secundarios, tales como solubilidad en agua y las interacciones secundarias no deseadas de unidades centrales, debido principalmente a reacciones intramoleculares. Sin embargo, finalmente se obtuvo una biblioteca combinatoria dinámica multivalente y se analizó con éxito mediante técnicas de HPLC-MS. El DCL, está basado en el intercambio de sulfuro para formar puentes di-sulfuro entre las diferentes unidades de azúcar. Esto fue posible gracias a la solubilidad en agua de las subunidades carboxilato y al uso de enlaces cortos entre los puntos de conexión del tiol y de la estructura central, evitándose la formación de enlaces intramoleculares.
Formación de una librería dinámica. Las partes se conectan a través de enlaces disulfuros.
Sin embargo, incluso cuando se controlaron los problemas mencionados anteriormente, la formación fiable y estable de los miembros de la librería era difícil debido a la desintegración sustancial durante la etapa de análisis. Por lo tanto, la posterior comparación de las afinidades de los miembros de la DCL no era posible. No obstante, los enfoques presentados ofrecen oportunidades para nuevos experimentos, que con una cuidadosa elección de las condiciones pueden conducir al éxito. Desafortunadamente, el marco temporal de esta tesis no lo permitió estudiar en detalle; había que seguir otras pistas más prometedoras.
La coordinación de ligando metal, especialmente con ligandos de tipo bipiridina coordinados a centros de FeII, evitó la mayoría de problemas encontrados anteriormente (parte desarrollada en el Capítulo 3). Observándose que en las condiciones necesarias para trabajar con la proteína elegida (ConA lectina) la formación de complejos era muy fiable.
Como primera prueba de concepto para un comportamiento de dinámica combinatoria, se evaluaron DCLs simples que no contenían azúcares sobre la base coordinativa bipyridina.
Una librería dinámica basada en el intercambio de ligandos de un centro metálico.
Después, DCLs que contenían azúcares fueron sintetizadas y fueron comprobadas con la proteína. Ligandos con sustituyentes azúcar fueron usados como bloques prefabricados, obteniéndose, mediante síntesis sencillas y con buenos rendimientos.
Ligandos con sustituyentes azúcares y basados en bipyridina que pueden formar complejos hexavalentes.
Métodos de HPLC bien elegidos permitieron el análisis de los DCLs, así como la determinación de las afinidades relativas con la lectina ConA. La cuantificación de las entidades con más afinidad apoyó el concepto de multivalencia para sistemas que intercambian dinámicamente múltiples unidades de reconocimiento.
A partir de este estudio básico, se desarrollaron otras DCLs que incorporaron componentes de diferentes geometrías. Las afinidades relativas de estos complejos compararon y revelaron que algunos miembros de la biblioteca contienen disposiciones tridimensionales más afines para la interacción con la lectina.
La proteína tiene más afinidad a un único miembro de la biblioteca dinámica
Por otra parte, los miembros de la librería de forma esférica parecen mostrar mayor afinidad a la proteína, en acuerdo con la teoría de “statistical rebinding”.
Una biblioteca dinámica de geometrías diferentes.
En resumen, DCLs basadas en la coordinación con metal (en contraste con enlaces covalentes dinámicos) han demostrado que constituyen una manera fácil de acceder a los procesos de intercambio multivalentes, proporcionando nuevas perspectivas para desentrañar las reglas de interacciones multivalentes de azúcares - lectina.
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Assailly, Coralie. "Conception et évaluation d'inhibiteurs multivalents de sialidases bactériennes." Thesis, Nantes, 2020. http://www.theses.fr/2020NANT4057.
Full textAbstract:
Les sialidases (SA) sont produites par de nombreux virus, bactéries et parasites. Le domaine catalytique (CAT) des SA bactériennes est souvent couplé à un domaine lectinique (CBM). Dans cette thèse, nous avons conçu des thiosialosides multivalents capables d’interagir simultanément dans les sites CAT et CBM des SA. L’activité inhibitrice des sialo-clusters formés a été testée sur les SA pathogènes de S. pneumoniae (NanA), V. cholerae (VcSA) et T. cruzi (TcTS). De forts effets synergiques ont été observés entre NanA et un poly-thiosialoside, où chaque motif sucre greffé possède une efficacité inhibitrice 3000 fois supérieure au composé monovalent de référence. Une étude approfondie de l’affinité de ce composé pour NanA, NanA CAT et NanA CBM, par résonnance plasmonique de surface et sur des biopuces a permis de proposer une explication à ce fort effet de synergie. Puis, nous avons développé des composés multivalents à base d’un inhibiteur plus puissant des sites CAT des SA, l’acide 2- désoxy-2,3-didéhydro-N-acétylneuraminique (DANA). Certains poly-DANA ont montré des concentrations inhibitrices subnanomolaires sur l’activité enzymatique de NanA, NanA CAT et de la SA de la bactérie commensale B. thetaiotaomicron (BtSA). Des études de modélisation moléculaire et l’obtention d’une structure cristallographique indiquent que cette forte interaction synergique s’effectue principalement sur la partie CAT et non sur le CBM des SA. L’ensemble de ces résultats suggère l’intérêt d’utiliser le concept de multivalence pour bloquer fortement la liaison des SA pathogènes aux sialosides de l’hôte, et inhiber leur activité catalytique<br>Sialidases (SA) are expressed by numerous viruses, bacteria and parasites. The catalytic domain (CAT) of bacterial SA is often flanked with a lectinic domain (CBM) that allows the enzyme to anchor to a sialoside surface for increasing its catalytic efficiency. In this work, we designed multivalent thiosialosides targeting both the CAT and CBM domains of SA. The inhibitory activity of the designed sialo-clusters was evaluated on pathogenic SA from S. pneumoniae (NanA), V. cholerae (VcSA) and T. cruzi (TcTS). Strong synergistic effects were observed between NanA and a synthetic polythiosialoside, where each grafted sugar unit has an inhibitory potency up to 3000 times higher than a reference monovalent thiosialoside. An in-depth study of the binding affinity of the multivalent thiosialosides for NanA and the truncated NanA CAT and NanA CBM domains was performed by surface plasmon resonance and by a biochip assay. Insight were provided in the binding mode operating. Then, we developed multivalent compounds based on a more potent inhibitor of the CAT domain, the 2-deoxy-2,3-dehydro-N-acetylneuraminic acid (DANA). Some poly-DANA showed inhibitory levels of the enzymatic activity in the subnanomolar range when assessed against NanA, NanA CAT or the SA from the commensal bacterium B. thetaiotaomicron (BtSA). Binding assays, molecular modeling studies, and crystallographic experiments suggest that this synergistic interactions probably occurs exclusively in the CAT and not the CBM domain. Altogether, these results suggest the interest of using the concept of multivalency to strongly inhibit the binding potency, and the catalytic activity of pathogenic SA
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MONI, Lisa. "SINTESI E PROPRIETA’ BIOLOGICHE DI LIGANDI GLICOSIDICI MULTIVALENTI." Doctoral thesis, Università degli studi di Ferrara, 2009. http://hdl.handle.net/11392/2389207.
Full textAbstract:
Protein-carbohydrate interactions are at the heart of many important biological processes as the
adesion of bacteria and viruses to the cell surfaces. It is widely accepted that nature compensates for
the low intrinsic affinity of carbohydrate for proteins through the cooperative binding between
multiple copies of ligands and receptors so that a strong adhesion results. This important concept,
termed cluster effect, has stimulated the search for the construction of highly glycosylated ligands
to inhibit polyvalent processes as well as probe for cell-surfaces-binding events. The aim of this
PhD research work was the synthesis of calix[4]arene-based glycoclusters via Cu(I)-catalyzed
azide-alkyne coupling reaction (CuAAC), as well as the investigation of their biological proprieties.
The first research conducted dealt with the synthesis of sialoside clusters as potential inhibitors of
viruses infectivity. Tetra- and octavalent sialoside clusters were prepared exploiting the multiple
copper-catalyzed cycloaddition of a propargyl thiosialoside with calix[4]arene polyazides. It was
demonstrated that these unnatural motifs did not hamper the desired biological activity of the
sialoclusters. In fact, they were able to inhibit, at submillimolar concentrations, the
hemagglutination and the viral infectivity mediated both by BK and influenza A viruses.
Then, this thesis focused on the possibility to support C-glycoside clusters on microarrays to study
their affinity against lectins. To this aim C-glycosylated calix[4]arenes have been synthesized in
which four galactose residues are linked through a triazole tether to the upper rim of the macrocycle
cavity while an azido group is present on the opposite side. Next the calixsugars were grafted
through CuAAC on mono or dipropargyloxymethyl-propanediol moieties allowing the synthesis of
oligonucleotides bearing one or two calixarene glycoclusters, respectively. Finally, their affinity for
lectins PA-IL and RCA 120, galactose specific lectins from Pseudomonas aeruginosa and Ricinus
communis, respectively, were compared to that displayed by linear and antenna-type glycoclusters.
During the last period of the PhD work it was performed the immobilization of calix[4]arenebased
glycoclusters on TiO2 nanoparticles via Cu(I)-catalyzed azide-alkyne coupling reaction. The
strategy that has been followed involved first the grafting of bis-functionalized calix[4]arenes
(azido groups at upper rim and fenolic or carboxylic groups at the lower rim) onto TiO2 and then
multiple click copper(I)-catalyzed cycloaddition
to propargil glycosides. The glyconanoparticles
obtained were characterized by thermogravimetric analysis (TGA) and infrared spectroscopy. This
constitutes the first example of TiO2 nanoparticles coated by a monolayer of calix[4]arene-based
glycoclusters.
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Dalvand, Parastoo. "Multivalent systems based on viologen units : redox behaviour and recognition properties by cucurbit[n]urils." Thesis, Strasbourg, 2015. http://www.theses.fr/2015STRAF051/document.
Full textAbstract:
Des supramolécules basées sur la reconnaissance de viologènes par des curcubit[n]urils (CB[n]) ont été étudiées. Les systèmes développées incluent des [3]-, [4]- et [7]pseudorotaxanes, composés de multimères à base de viologène et de CB[7] ou CB[8]. L’étude physicochimique a montré que ces supramolécules sont interconverties électrochimiquement entre un état complexé, défini par les pseudorotaxanes, et un état dissocié comprenant chacun des partenaires. Le désassemblage résulte d’une pimérisation intra/intermoléculaire entre radicaux viologènes.L’étude physicochimique de complexes pentacoordinés basés sur la reconnaissance d’azo-aryl-imidazoles par une porphyrine à anse phénanthroline a été menée; l’objectif étant d’utiliser les propriétés d’isomérisation photoinduite trans-cis d’azo-chromophores pour dissocier ces complexes. Les complexes initiaux sont alors régénérés par relaxation thermique. La stabilité et les propriétés cinétiques des complexes pentacoordinés ont été évaluées<br>Supramolecules based on the recognition of redox-active bipyridiniums by cucurbit[n]uril (CB[n]) have been studied. The investigated systems include a [3]-, a [4]- and a [7]pseudorotaxane, each of them composed of a multimeric viologen-based thread molecule and CB[7] or CB[8]. The physicochemical approach emphasized that these systems can be electrochemically switched between a complexed state, defined by the pseudorotaxanes, and an uncomplexed state comprising their components. The disassembly results from intra/intermolecular pimerization of the viologen radicals.A physicochemical approach of pentacoordinated complexes of a phen-strapped porphyrin with azo-arylimidazoles has been undertaken with the aim to use the photoinduced trans-cis isomerization properties of azo-chromophores to dissociate the complexes. Thermal equilibration reinstates the thermodynamically favoured complexes. The strength and the kinetic properties of these pentacoordinated species have been evaluated
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Glanz, Maria. "Chemoselective conjugation of biological active peptides to functional scaffolds." Doctoral thesis, Humboldt-Universität zu Berlin, 2019. http://dx.doi.org/10.18452/20223.
Full textAbstract:
Peptide bilden eine einzigartige Klasse von Biomolekülen. Auf Grund ihrer komplexen Struktur sind sie in der Lage hochspezifisch an Zielmoleküle zu binden und können darüber hinaus bioaktive Eigenschaften aufweisen. In dieser Dissertation wurden verschiedene Anwendungen, für die biologisch aktive Peptide genutzt werden können untersucht und darüber hinaus die Konjugation ungeschützter Peptide an funktionelle Gerüstmoleküle betrachtet. Die spezifischen Bindungseigenschaften eines Hemagglutinin bindenden Peptids konnten durch deren multivalente Präsentation auf einem Polymer-Nanopartikel genutzt werden, um einen hochwirksamen Virus-Eintritts-Blocker zu synthetisieren. Außerdem wurde in dieser Dissertation eine neuartige chemoselektive Konjugation zwischen ungeschützten zyklischen Peptiden und Proteinen erforscht, basierend auf der Staudinger Phosphonite Reaktion. Die kovalente Bindung zwischen Proteinen und Peptiden ermöglichte die zellulären Aufnahme und zytosolische Verteilung des konjugierten Proteins. Die neuartige Staudinger induzierte Thiol Addition konnte darüber hinaus für die intramolekulare Makrozyklisierung von Peptiden eingesetzt werden, wodurch die biologische Aktivität der Peptide gesteigert wurde. Dies konnte anhand von zyklischen zellpenetrierenden Peptiden, als auch in der Stabilisierung der helikalen Struktur eines peptidischen Protein-Protein-Interaktions Inhibitors gezeigt werden. Des weiteren wurde eine bioreversible chemoselektive Konjugationsmethode untersucht, basierend auf der O-Alkylierung von Carbonsäuren, um eGFP mit zyklischen zellpenetrierenden Peptiden zu markieren. Erste Schritte zur Evaluierung der entstandenen Konjugate wurden unternommen. Zusammengenommen konnte die Vielfältigkeit bioaktiver Peptide in mehreren Anwendungen gezeigt werden, mit besonderem Augenmerk auf die Erweiterung der Konjugationsmethoden für ungeschützte Peptide an funktionale Trägermoleküle.<br>Synthetic peptides are a unique class of biomolecules. Due to their complex structure they can bind targets in a highly specific manner and can furthermore exhibit unique properties. Even though they are complex in structure, they are straightforward synthetically accessible. This thesis evolves around the many different aspects, in which biological active peptides can be used, from specific binders to cell penetration tags. Furthermore, the site specific and chemoselective conjugation of an unprotected peptide to a functional scaffold has been addressed. The binding properties of peptides could be used to generate a highly potent virus entry blocker from a viral-membrane-protein binding peptide, which was displayed multivalently on a polymeric nanoparticle. Furthermore, this thesis explored a novel chemoselective reaction, based on the Staudinger phosphonite reaction to conjugate cyclic peptides to eGFP. The covalent attachment of the peptidic ligand promoted efficiently the cellular uptake of protein and its cytosolic distribution. The novel Staudinger induced thiol addition cascade was further successfully used in an intramolecular reaction to macrocyclize peptides in order to induce bioactivity. This could be shown for the synthesis of cyclic cell penetrating peptides, as well as to stabilize the helical structure of a peptidic protein-protein interaction inhibitor. Furthermore, a bioreversible chemoselective conjugation based on a diazo building block, was used to label eGFP with cyclic cell penetrating peptides. First steps to evaluate the potency in vitro were undertaken. Taken together, the versatility of bioactive peptides was demonstrated in multiple applications and the tools to conjugate unprotected peptides to functional scaffolds was extended by the Staudinger induced thiol addition.
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Zanini, Diana. "Quantitative multivalent carbohydrate-protein interactions from novel glycodendrimers." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape16/PQDD_0016/NQ28389.pdf.
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Lin, Wenyuan. "Bodies in action : multivalent agency in haemodialysis practices." Thesis, Lancaster University, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.429970.
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Aleksic, Stevan [Verfasser]. "Conformational Dynamics of the Multivalent Targets / Stevan Aleksic." Berlin : Freie Universität Berlin, 2018. http://d-nb.info/1176632760/34.
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Achazi, Andreas Johannes [Verfasser]. "Theoretical Investigations of Multivalent Reactions / Andreas Johannes Achazi." Berlin : Freie Universität Berlin, 2017. http://d-nb.info/1148426264/34.
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Keyzer, Evan. "Development of electrolyte salts for multivalent ion batteries." Thesis, University of Cambridge, 2019. https://www.repository.cam.ac.uk/handle/1810/288431.
Full textAbstract:
This dissertation focuses on the synthesis and electrochemical testing of new electrolyte salts for rechargeable multivalent ion batteries. In chapters 2 and 3 the synthesis of Mg and Ca hexafluoropnictogenate salts as well as the electrochemical behaviour of Mg(PF6)2 is presented. Pure samples of Mg(EF6)2 (E = P, As, and Sb) can be synthesized using Mg metal and NOPF6/NOSbF6 in CH3CN or via a ammonium salt deprotonation route using Me3NHAsF6 and Bu2Mg. The NOPF6 method was extended to the Ca variant, but isolation of a pure Ca(PF6)2 material required the presence of a crown ether. Electrochemical and microscopy measurements of THF-CH3CN solutions of Mg(PF6)2 show that the electrolyte good electrochemical stability and can facilitate the plating/stripping of Mg. Further, this electrolyte system can be cycled in a full cell using the Chevrel phase Mo6S8 cathode. The electrochemical stability of the AsF6− and SbF6− salts is lower than that of the PF6− salt and electrolyte decomposition is observed when cycling on Mg electrodes. In chapter 4 the development of a series of Mg aluminates [Mg(AlOR4)2] using a general synthetic platform based on Mg(AlH4)2 and various alcohols is presented. Preliminary electrochemical studies performed on these aluminate salts in dimethoxyethane identify the phenoxy and perfluoro-tert-butoxy derivatives as promising electrolyte systems. Electrochemical cycling of these electrolytes using gold and Mg electrodes show that systems containing chloride, brought through to the product from the starting material in the form of NaCl, exhibit lower plating/stripping overpotentials and higher Coulombic efficiencies than systems from which chloride had been removed. Further, these two electrolytes can be used in Mg full cells containing the Chevrel phase cathode. Solid-state 23Na NMR analysis as well as DFT calculations show that chloride-containing electrolytes facilitate the co-insertion of Na into the cathode material. In chapter 5 the hydroboration of pyridines and CO2 in the presence of pinacolborane is presented. An optimized system employing NH4BPh4 and HBpin is developed and a mechanism of pyridine hydroboration is proposed based on multinuclear NMR spectroscopy. The catalytic reaction was found to be catalyzed by a boronium salt, which was structurally characterized in the solid-state by single crystal X-ray diffraction. This new catalytic method is shown to be tolerant to a number of functional groups in the 3-position on pyridine as well as quinoline, and CO2, producing the hydroboration products in good yields.
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Hewitt, Sarah Helen. "Multivalent scaffolds for use as protein surface mimetics." Thesis, University of Leeds, 2017. http://etheses.whiterose.ac.uk/18027/.
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The development of ligands for protein surfaces to inhibit protein-protein interactions (PPI)s is challenging, as protein surfaces often lack the clefts and pockets associated with traditionally druggable targets like enzyme active sites. One way in which protein surfaces can be targeted is by the use of protein surface mimetics, whereby a multivalent scaffold is functionalised with many binding groups on its periphery in order to achieve high affinity protein recognition. One such scaffold is a ruthenium(II) tris (bipyridine)s (Ru(II)(bpy)3). The work in this thesis aimed to further develop these Ru(II)(bpy)3 protein surface mimetics; gaining information as to how they interact with proteins, looking at new ways of achieving high affinity protein surface recognition and the development of new applications for these molecules. In Chapter 2 an indepth study of the binding of two Ru(II)(bpy)3 complexes to a model protein, cytochrome c, is presented, looking at the thermodynamic and electrostatic contributions to binding as well as using protein NMR to elucidate the binding site. In Chapter 3 the development of dynamic combinatorial chemistry (DCC) scaffolds based on Ru(II)(bpy)3 complexes and tetraphenyl porphyrins was explored as a potential avenue for new receptor design, enabling the development of biologically compatible DCC systems, prime for protein ligand discovery. Chapter 4 presents another avenue for using the Ru(II)(bpy)3 complexes; using an array approach to discriminate between different protein.
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Hill, Stephen Andrew. "Carbohydrate-based carbon dots as multivalent glycan platforms." Thesis, University of Bristol, 2017. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.743030.
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