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1
Nemeth, Richard Desider. "Linked Beta-Cyclodextrins." W&M ScholarWorks, 1988. https://scholarworks.wm.edu/etd/1539625449.
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Liu, Enxu. "Design of molecular Brownian ratchets exploiting the asymmetry of functionalized cyclodextrins." Electronic Thesis or Diss., Sorbonne université, 2023. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2023SORUS654.pdf.
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Au cours des dernières années, les avancées dans le domaine des machines moléculaires ont été remarquables. Néanmoins, la réalisation d'un mouvement unidirectionnel contrôlé au sein de ces nanostructures reste compliquée. L'objet de cette thèse est d'exploiter l'asymétrie intrinsèque de la cyclodextrine (CD) pour développer des machines moléculaires capables de réaliser un mouvement unidirectionnel. Une série de [2]rotaxanes, comportant une α-CD perméthylée simple ou fonctionnalisée avec une amine sur le col primaire a été synthétisée.Dans une première partie, un mécanisme de cliquet d'information a été mis au point sur un [2]rotaxane de CD perméthylée. Il a été observé que la cinétique de protection de l'axe par des groupements Fmoc dépend de l'orientation et de la position de la CD. Ces données suggèrent que la forme conique asymétrique du macrocycle instaure un mécanisme original de type cliquet d'information, ouvrant des perspectives pour la conception de moteurs moléculaires de nouvelle génération.Dans une seconde partie, l'introduction d'une fonction diméthylamine sur le col primaire de la CD du [2]rotaxane a été réalisée. Cette modification vise à catalyser la déprotection intramoléculaire du groupement Fmoc devant le col primaire de la CD. Ce hypothèse a été optimisé sur un système de [2]rotaxane modèle. Un mouvement unidirectionnel à travers un processus cyclique de protection et de déprotection du Fmoc semble accessible. Ces résultats démontrent l'intérêt de la construction des moteurs moléculaires avec des CD fonctionnaliséesOver recent years, molecular machines have been widely developed, yet mastering unidirectional movement in these nano-entities remains challenging. This thesis focuses on harnessing the inherent asymmetry of cyclodextrin (CD) to design molecular machines that are able to perform unidirectional motion. A range of [2]rotaxanes, incorporating methylated α-CD, either amine-functionalized at the primary rim or permethylated was synthesized.In the first part, an information ratchet system was discovered on a permethylated α-CD [2]rotaxane. The kinetics of the Fmoc protection of the axle are influenced by the CD's orientation and position. These findings suggest that the asymmetric conical shape of the macrocycle establishes a unique information ratchet mechanism, paving the way for the design of next-generation molecular motors.In the second part, the introduction of a dimethylamine function on the primary rim of the CD of the [2]rotaxane was carried out. This modification aims to catalyze the intramolecular deprotection of the Fmoc group faces to the primary rim of the CD. This hypothesis was optimized on a model [2]rotaxane system. A unidirectional movement through a cyclic process of protection and deprotection of the Fmoc appears feasible. These results highlight the potential of building molecular motors with functionalized CDs
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Brown, Susan Elizabeth. "Molecular recognition by cyclodextrins /." Title page, contents and abstract only, 1994. http://web4.library.adelaide.edu.au/theses/09PH/09phb8798.pdf.
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Yan, Jinglan. "Sulfated ß-cyclodextrins in enantiomeric separations and mobility conservation model in cyclodextrin-mediated capillary electrophoresis." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ35009.pdf.
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Haskard, Carolyn Anne. "Multiple recognition by modified cyclodextrins." Title page, contents and abstract only, 1996. http://web4.library.adelaide.edu.au/theses/09PH/09phh349.pdf.
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Copy of author's previously published article inserted. Includes bibliographies This thesis studies the B-cyclodextrins which are modified at the primary rim to incorporate an additional coordination or hydrophobic recognition site. The natural organic host, cyclodextrin and its chemically modified derivatives, are utilised as hosts for the inclusion of a range of guests. The study contributes to understanding the fundamental factors influencing selectivity of binding and the stability of the complexes formed when a guest is bound essentially at two recognition sites.
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Kean, Suzanna Dawn. "Modified cyclodextrins and their complexes." Title page, contents and abstract only, 1999. http://web4.library.adelaide.edu.au/theses/09PH/09phk243.pdf.
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Addendum page pasted onto front end paper. Copies of author's previously published articles inserted. Includes bibliographical references. Investigates the factors that govern the stability of cyclodextrin inclusion complexes with a range of systematically modified cyclodextrins.
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Palmer, Simon Richard Faunch. "Electroanalytical sensors using lipophilic cyclodextrins." Thesis, Durham University, 1997. http://etheses.dur.ac.uk/4753/.
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Lipophilic dialkylated-a-, β- and γ-cyclodextrin derivatives were used as selective ionophores for a series of clinically relevant ammonium ions, and as enantioselective ionophores for both a- and β-aryl ammonium ions. Sensitive and selective potentiometric detection of the local anaesthetics lidocaine and bupivacaine was achieved by using 2,3,6 trioctyl-β-cyclodextrin as the ionophore, leading to micromolar detection limits. Interference studies showed that the simulated clinical electrolyte background caused minimal interference whereas organic interferents of similar size and charge caused some perturbation of the electrode response at a concentration of 10 mmol dm(^-3). An electrode comprising a plasticized biocompatible membrane matrix, TECOFLEX, with 2,6 didodecyl-β-cyclodextrin was incorporated in a flow injection analysis system and the response to lidocaine studied in the presence of human serum. Human serum caused no adverse effects to the electrochemical response of the electrode. These electrodes are, therefore, very suitable for on-line detection of local anaesthetics. Potentiometric detection of tricyclic antidepressants using didodecyl-a-, β- and γ- cyclodextrins as the ionophore, gave micromolar detection limits. Interference from simulated clinical electiolyte background and selected organic interferents gave similar results to those discussed above. In order to lower the detection limit to sub-nanomolar levels modified amperometric electrodes were assembled by depositing a membrane comprising plasticised TECOFLEX, 2,3,6 triethyl-β-cyclodextrin and TKB on the working electrode of a screen printed electrode. Lipophilic 2,6 didodecyl-a- and β-cyclodextrins exhibited enantiomeric discrimination in the binding of propranolol, ephedrine, amphetamine and methamphetamine. These results were confirmed using potentiometric and NMR techniques.
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Jones, S. P. "Interaction of drugs with cyclodextrins." Thesis, University of Nottingham, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.355923.
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De, Vries Elise Janine Christl. "Inclusion of alkylparabens in cyclodextrins." Doctoral thesis, University of Cape Town, 2003. http://hdl.handle.net/11427/6302.
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Includes bibliographical references.The aim of this thesis was to prepare crystalline inclusion complexes with cyclodextrins (CDs), as hosts, and drugs, as guests, characterise them using various methods and attempt to elucidate their structures by X-ray diffraction methods to establish the detailed mode of drug inclusion in the solid state. Cyclodextrins and their derivatives have a low polarity central void formed by linked glucose residues of varying numbers. This annular cavity is able to encapsualte low molecular weight molecules and is therefore responsible for the great interest in CDs in host-guest chemistry. In addition, inclusion of drug molecules in cyclodextrins can significantly improve aspects of their performance, such as increased aqueous solubility and dissolution rates which lead to their increasing application in the pharmaceutical industry.
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Al-Derbali, Meftah Abdulhafied. "Formulation and evaluation of zidovudine cyclodextrin inclusion complex to enhance acid lability and palatability." University of the Western Cape, 2016. http://hdl.handle.net/11394/5052.
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Magister Pharmaceuticae - MPharmBackground: Zidovudine (AZT) is a very useful drug for the management of Human Immunodeficiency Virus (HIV) infection. Its optimal use is limited by its bitter taste, sparing solubility (20.1 mg/ml) and acid lability. Cyclodextrins (CD) are a class of compounds which can be used to form inclusion complexes with drugs such as AZT to improve it is taste, solubility and palatability. Purpose: This study complexed hydroxypropyl-beta-cyclodextrin (HPβCD) with AZT. The formulated inclusion complex was evaluated for suitability as a dosage form and as a tool for improving AZT’s palatability, solubility and acid liability. Method: AZT was complexed with HPβCD using the lyophilisation method. The binding constant for the formulation was determined by the phase solubility method, and complex formation between AZT and HPβCD evaluated using proton nuclear magnetic resonance (1H NMR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and hot stage microscopy (HSM). Tablets of the inclusion complex were formulated by direct compression, using the least possible amount of excipients, and the dosage form evaluated for hardness, friability, durability, disintegration time and dissolution. Results: The binding constant of the formulation was 3.919, and the degree of incorporation was 4.0 mg AZT/g of CD per complex. 1H NMR showed significant chemical shifts between the inclusion complex and AZT. DSC and TGA analyses showed significant differences in the curves for the pure AZT and HPβCD. Values for tablet hardness, friability, durability and disintegration time were 236 ± 20 N, 0.7 %, 1.02 % and 10.25 minutes, respectively. The solubility of the formulation was 148.08 mg/ml, and its dissolution profile was different from that of the branded formulation. Conclusions: AZT-HPβCD inclusion complex, with a 7.4-fold increase in AZT solubility, was successfully prepared using the lyophilisation method. The binding constant and friability of the formulation were within acceptable limits. Although the hardness value is high, the tablet still disintegrated within acceptable specified times. This study has significant implications for anti-retroviral complex formulations.
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Lock, Julia. "Cyclodextrins : molecular wheels for supramolecular chemistry /." Title page, table of contents and abstract only, 2004. http://web4.library.adelaide.edu.au/theses/09PH/09phl8131.pdf.
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Thesis (Ph.D.)--University of Adelaide, School of Chemistry and Physics, Discipline of Chemistry, 2005?"July 2004" Includes copies of publications by the author as appendix. Includes bibliographical references.
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Lee, Yann-Huei Phillip Ramapuram Jayachandra B. "Inclusion complexation of Gefitinib with cyclodextrins." Auburn, Ala, 2008. http://repo.lib.auburn.edu/EtdRoot/2008/SUMMER/Pharmacal_Sciences/Thesis/Lee_Yann-huei_47.pdf.
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Cossette, Michael Vernie. "The Synthesis of Quinone-Capped Cyclodextrins." W&M ScholarWorks, 1988. https://scholarworks.wm.edu/etd/1539625451.
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Meijide, Suárez Jorge. "Confinement of metal complexes in NHC-cyclodextrins : structure, electrochemistry and catalysis." Thesis, Sorbonne université, 2018. http://www.theses.fr/2018SORUS539.
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L'utilisation de métaux confinés dans des cavité est un outil intéressant dans le domaine de la catalyse en milieu confiné. Grâce à la forme conique des cyclodextrines (CD), la synthèse des NHC-pontées dérivés (ICyD) a été étudié. L’étude commence par la synthèse et la caractérisation de dérivés de Au(I) dans la cavité de la y-ICyD. Au cours de la synthèse, la formation d'un complexe AuCl3 plan carré (y-ICyD) a été observée. Celui-ci a conduit à la synthèse de complexes Au(III), Pd(II) et Pt(0) complexés par les ⍺-, β- et γ-CDs. Les structures 3D des complexes ont pu être modélisées grâce à l’étude des protons situés à l’intérieur de la cavité en RMN, en utilisant les interactions faibles (H-X ou H-M). Les propriétés chimiques des complexes Au(I) et Pd(II) ont été étudiées en voltamétrie cyclique. Ces complexes se sont révélés être les premiers complexes non silencieux à l’intérieur de la cavité d’une CD. L’utilisation des complexes (ICyD)AuCl dans une réaction de cycloisomérisation d’ényne a révélé que ces composés étaient des ligands efficaces en catalyse énantioselective. Les complexes confinés de (β-ICyD) à base de Pd ont été étudiés dans une réaction monoarylation sélective d'amines ainsi que dans une homoallylation d’aldéhydes aromatiques, sélective en fonction de la taille du substratThe use of mononuclear confined metals inside discrete molecular pockets was proved to be a powerful tool in the confined catalysis field. Due to the conical shape of cyclodextrins (CD), these macrocycles are perfect candidates for the synthesis and applications of confined metals. In this work, the synthesis of NHC-capped cyclodextrins (ICyD) complexing metal centers inside the cavity was studied. The discussion starts with the synthesis and characterization of Au(I)-derivatives inside the y-ICyD cavity. During the synthesis, the formation of the square planar complex, (y-ICyD)AuCl3, was observed. This unexpected product led to the synthesis Au(III), Pd(II) and Pt(0) complexes in ⍺-, β- and y- CDs. Supported by the effects of the weak interactions on the intra-cavity protons in the NMR, the 3D structures of the complexes were modeled. The electrochemical properties of the Au(I) and Pd(II) complexes were studied by cyclic voltammetry, being the first non-silent complexes inside a CD cavity. The catalytic applications of the CD-based complexes were also studied. The chiral ICyD skeleton was proved to be an efficient ligand in an enantioselective Au-catalyzed enyne cycloisomerization. The introverted (β-ICyD)Pd complexes were found to be efficient catalysts for a selective monoarylation of amines, as well as, size-selective catalysts in a homoallylation of aromatic aldehydes
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Field, Michael J. "6A-w-Aminoalkylamino-Cyclodextrins : their preparation and studies of their self-inclusion complexes and catalytic nature /." Title page, contents and abstract only, 2000. http://web4.library.adelaide.edu.au/theses/09PH/09phf455.pdf.
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Thesis (Ph.D.)--University of Adelaide, Dept. of Chemistry, 2000?Copy of author's previously published article, inserted. Errata sheet pasted opposite title page. Includes bibliographical references.
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Colesnic, Dmitri. "Architectures supramoléculaires hiérarchiques à base de cyclodextrines." Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066616/document.
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La Nature crée des assemblages, de structure primaire (1D) et secondaire (3D) bien maîtrisées, qui réalisent des fonctions biologiques complexes. Dans ce contexte, notre but est de construire des assemblages supramoléculaires hiérarchiques utilisant des monomères de cyclodextrines (CDs), préparés selon la méthode de polyfonctionnalisation des CDs, développée au laboratoire. L'existance d'équilibres compétitifs (auto-inclusion et dimérisation tête à tête) empêchant l'accès aux polymères supramoléculaires (PS) de plus grande taille, a été démontrée. Ainsi, pour s'affranchir de ces espèces compétitives, une stratégie de pontage a été adoptée. Deux familles de composés (mono- et disubstitués) ont été développées montrant des comportements différents. Les composés monosubstitués forment des oligomères supramoléculaires en solution, tandis qu'un assemblage supramoléculaire hiérarchique à l'état solide (trois niveaux) est obtenu avec les dérivés disubstitués. Par ailleurs, le monomère monosubstitué chargé positivement a conduit à une compaction efficace d'une matrice d'ADN double brin, grâce à l'assistance de l'interaction hydrophobe. D'autre part, dans le but de controler la taille d'un polymère supramoléculaire à base de CD, un monomère possédant deux fonctions orthogonales (hôte-invité et paire de base) a été développé. En présence d'une matrice simple brin, la formation d'un pseudo-duplexe d'ADN a été observée, stabilisé grâce à la synergie de l'interaction hydrophobe et de l'appariement des paires de basesBiological macromolecules and their assemblies (such as enzymes or viruses) perform extremely complex functions, thanks to their structural control. Our aim is to mimic such elaborated tools and build synthetic hierarchical assemblies using building blocks of cyclodextrin (CD). Using the known DIBAL-H reactivity for polyfonctionalization of CDs several monomers were prepared containing host-guest and electrostatic interactions. Thus, we demonstrated that a competitive self-inclusion and head to head dimerization prevent the formation of larger species in solution. To overcome this problem, a bridging strategy was used to cap the CD monomer and attach the two functionalized sugar units. This led to two types of building blocks (mono- and di-substituted) that showed different beahaviour. The monosubstituted compounds formed supramolecular oligomers in solution while disubstituted ones led to a hierarchical supramolecular self-assembly in the solid-state. Furthermore, efficient DNA compaction was performed involving hydrophobic interaction as a result of the use of monosubstituted positively charged CD building blocks. On the other hand, a single stranded DNA was used to control the size of CD-based supramolecular polymers. For this purpose, a CD monomer containing a hydrophobic moiety and a trinucleotide was developed. The host-guest and base pair interaction synergy allowed the formation of a stable DNA pseudo-duplex
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Jarand, Curtis William. "Complexation of Organic Guests and Coordination of Metal Ions by Cyclodextrins: Role of Cyclodextrins in Metal-Guest Interactions." ScholarWorks@UNO, 2011. http://scholarworks.uno.edu/td/1319.
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Nitroaromatic explosives, such as trinitrotoluene (TNT), are of particular environmental concern due to their recalcitrance in soils and their potent toxicity and mutagenicity to both aquatic and mammalian species. TNT was the most widely used military explosive through the era encompassing both the First and Second World Wars. As a result, there is widespread contamination of soils by TNT around weapons manufacture, testing, and disposal facilities. Fenton chemistry (ferrous ion catalyzed generation of hydroxyl radicals) has shown utility in the remediation of TNT in soils but it suffers from non-specificity and the need for acidic conditions to prevent loss of iron as iron hydroxides. Cyclodextrins (CDs) have demonstrated the ability to increase the efficiency of Fenton degradation of aromatic pollutant species. The increase in degradation efficiency observed in the CD Fenton reaction systems has been credited to the formation of a pollutant/CD/ferrous ion ternary complex which has the ability to produce hydroxyl radicals at the site of bound ferrous ions during Fenton reactions. This results in an increase in hydroxyl radical concentration near the target guest molecule relative to the bulk solution, leading to a targeted degradation of the complexed guest molecule. In order to assess the viability of CD assisted Fenton reactions for the remediation of TNT, a thorough knowledge of the kinetics, degradation products, and role of binary and ternary complexes is required. Research presented in this dissertation examined the role of CDs in the Fenton oxidation of TNT, specifically: 1) the kinetics of TNT degradation in the presence of CDs for a Fenton reaction system, 2) the products of these reactions through chromatographic and mass spectrometric methods, and 3) NMR and binding studies of binary and ternary complexes.
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Serno, Tim. "Inhibition of therapeutic protein aggregation by cyclodextrins." Diss., lmu, 2010. http://nbn-resolving.de/urn:nbn:de:bvb:19-131251.
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Martinic, Goran (Gary), of Western Sydney Hawkesbury University, of Science Technology and Environment College, and School of Environment and Agriculture. "Cyclodextrins as potential human anti-atherosclerotic agents." THESIS_CSTE_EAG_Martinic_G.xml, 2001. http://handle.uws.edu.au:8081/1959.7/129.
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Cyclodextrins (CDs) are naturally occurring cyclic oligosaccharides. Since it is believed that OxC blocks the removal of normal cholesterol from cells in the artery wall, it is possible that selective removal of OxC in the vessel wall in-vivo may prevent or reverse atherosclerosis.As a prelude to major studies, this research project was designed to answer two critical questions; 1/. What is the best route for delivery of CD. 2/. How do animals (apoE-/- mice) tolerate it. Pilot studies were established and results noted. These studies have provided valuable information in the apoE-/- mouse for subsequent studies to prevent or reverse atherosclerosis in this animal model.Master of Science (Hons)
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Bauer, Martin. "Membrane functionalisation using polyrotaxanes with amphiphilic cyclodextrins." Strasbourg, 2011. http://www.theses.fr/2011STRA6190.
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Ce travail est destiné à la conception et à la caractérisation d’une nouvelle famille de ligands attachés, appelé “Sliding Tethered Ligands” (STLs). Ils sont à base de complexes topologiques entre des polymères et des cyclodextrines amphiphiles (CD), qui peuvent être insérées dans les membranes phospholipidiques. Au début, nous étudions les propriétés d’insertion membranaire des dérivés de CD amphiphiles modifiées avec du cholestérol, qui sont des ancres membranaires appropriées pour les STLs. Avec l’aide de la réflectivité de neutrons on peut démontrer que les résidus de CD montrent une remarquable adaptabilité de conformation et que les cavités de CD restent accessibles lors de l’insertion dans des membranes modèles lipidiques. Nous avons développé une voie de synthèse pour assembler le STL à partir des polyrotaxanes avec un très bas nombre contrôlé des CDs mono-modifiées avec un groupe azido, enfilées sur une chaine de polyéthylène glycol (PEG). En utilisant de nouvelles méthodes in situ les polyrotaxanes sont bouchonnés avec des ligands d’adamantane, qui peuvent être reconnus par des récepteurs de beta-CD. Par ailleurs, une ancre membranaire de cholestérol est jointe aux CDs complexées afin de permettre au STLs à s’insérer dans les membranes. Nous démontrons que les STLs sont très bien ancrés dans des membranes modèles phospholipidiques (DPPC). Pour des densités de polymère suffisamment élevées les STLs forment des brosses de polymères qui suivent les lois d’échelle prédite par la théorie du champ moyen. En utilisant une machine de force, nous montrons que des membranes modèles modifiées avec des STLs et des récepteurs de cholestérol beta CD donnent lieu aux profils d’interaction typiques entre des ligands et des récepteursThis work is aimed at the design and characterisation of a new family of tethered ligands, called sliding tethered ligands (STLs). They are based on topological complexes between polymers and amphiphilic cyclodextrins (CDs), which can be inserted into phospholipid membranes. At first we investigate the membrane insertion properties of amphiphilic cholesteryl CD derivatives, which are suitable membrane anchors for the STLs. With the help of neutron reflectivity it can be demonstrated that the CD residues show a remarkable conformational adaptability and that the CD cavities remain accessible upon insertion into lipid model membranes. We have developed a synthetic pathway to assemble the STLs from polyrotaxanes with a controlled low number of mono-modified azido-alpha-CDs, threaded on a polyethylene glycol (PEG) chain. Using newly developed in-situ capping methods the polyrotaxanes are endcapped with adamantane ligands, which can be recognized by a beta-CD receptor. Furthermore a cholesteryl anchor is attached to the threaded CDs in order to enable the STLs to insert into membranes. We demonstrate that STLs readily insert into phospholipid (DPPC) model membranes using IR Absorption Reflection Spectroscopy and investigating the film morphology by Brewster Angle Microscopy and Atomic Force Microscopy. Applying neutron reflectivity it is shown, that for sufficiently high polymer densities the STLs form polymer brushes, which follow the scaling laws predicted by the mean field theory. Using the surface force apparatus it is evidenced that model membranes modified with STLs and cholesteryl beta-CD receptors give rise to typical tethered ligand - receptor interaction profiles
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Martinic, Gary. "Cyclodextrins as potential human anti-atherosclerotic agents." Thesis, View thesis View thesis, 2001. http://handle.uws.edu.au:8081/1959.7/129.
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Cyclodextrins (CDs) are naturally occurring cyclic oligosaccharides. Since it is believed that OxC blocks the removal of normal cholesterol from cells in the artery wall, it is possible that selective removal of OxC in the vessel wall in-vivo may prevent or reverse atherosclerosis.As a prelude to major studies, this research project was designed to answer two critical questions; 1/. What is the best route for delivery of CD. 2/. How do animals (apoE-/- mice) tolerate it. Pilot studies were established and results noted. These studies have provided valuable information in the apoE-/- mouse for subsequent studies to prevent or reverse atherosclerosis in this animal model.
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Martinic, Gary. "Cyclodextrins as potential human anti-atherosclerotic agents /." View thesis View thesis, 2001. http://library.uws.edu.au/adt-NUWS/public/adt-NUWS20030505.174617/index.html.
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Thesis (M.Sc.) (Honours) -- University of Western Sydney, Hawkesbury, 2001.A thesis submitted in fulfilment of the rquirements for the award of the degree of MSc(Hons), University of Western Sydney, Hawkesbury Campus, 2001. Bibliography : leaves 263-294.
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Worthington, Matthew Stanley. "Nifedipine-cyclodextrin binary systems : solid-state photostability and dissolution behaviour." Thesis, Rhodes University, 1998. http://hdl.handle.net/10962/d1007233.
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Nifedipine is a photolabile calcium channel antagonist which undergoes rapid photodegradation in solution and in solid-state with an accompanying loss of pharmacological potency and clinical efficacy. Nifedipine photostabilization which has received considerable attention has principally been achieved by physical obscuration and through the use of colourants or ultraviolet light absorbers incorporated into liquid preparations, translucent packaging materials, gelatin capsules and/or their fillings and tablet coatings or cores. This study was initiated by a South African pharmaceutical manufacturer in response to increasing evidence that cyclodextrin (CD) inclusion complexation may improve drug photostability. The brief was to evaluate the potential of selected cyclodextrins as photoprotecting agents for nifedipine in the solid-state. Areas of investigation included i) quantitative method development and validation for selective determination of nifedipine, ii) phase solubility studies to establish the solubilizing potential and complexing tendencies of selected cyclodextrins, iii) preparation of solid-state nifedipine - cyclodextrin binary systems using an industrially applicable method, iv) pre-formulation photostability studies to determine the effects of the cyclodextrins on solid-state nifedipine photostability and v) comparative in vitro dissolution assessments of nifedipine, the nifedipine - cyclodextrin binary systems and their respective physical mixtures. Phase solubility studies demonstrated that soluble nifedipine - cyclodextrin complexes were formed in aqueous solution, but the magnitude of the interactions were generally low as reflected by the calculated stability constants which decreased in the rank order, heptakis (2,6-dimethyI)-β-CD (DM-β-CD) > randomly methylated-β-CD (RM-β-CD) > β-CD ≈ 2-hydroxypropyl-β-CD (2HP-β- CD) > γ-CD ≥ 2-hydroxypropyl-γ-CD (2HP-γ-CD). An industrially applicable kneading method yielded binary systems with spectral and thermal characteristics similar to the respective physical mixtures, implying weak solid-state inclusion complexation. Preparation of an amorphous nifedipine - RM-β-CD product using a heating method is reported. A 1.7- and 1.9-fold improvement in solid-state nifedipine photostability was observed for I : 1 molar ratio β-CD and γ-CD kneaded products, respectively, when exposed to window-filtered daylight and could be attributed to changes in opacity of the crystalline kneaded products. The remaining cyclodextrins produced negligible nifedipine photostabilization. Nifedipine in vitro dissolution was improved considerably from γ-CD and RM-β-CD .kneaded products as a result of increased nifedipine wettability, solubility and reduced particle size. iii
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Åström, Nina. "NADH/NAD⁺ analogues and cyclodextrins in enzyme mimicking systems an experimental and computational investigation /." Lund : Organic Chemistry 1, Lund University, 1995. http://catalog.hathitrust.org/api/volumes/oclc/39781586.html.
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Murphy, Robert Scott. "Photophysical studies on the dynamics of guest complexation with cyclodextrins." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0017/NQ47292.pdf.
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Anil, Gunaratne D. M. "Physical and chemical modification of some cereal, tuber and root starches and the roles of [beta]-cyclodextrin as a starch modifying agent." Click to view the E-thesis via HKUTO, 2006. http://sunzi.lib.hku.hk/hkuto/record/B37752753.
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Zhang, Pinglu. "Cyclodextrin-(N-Heterocyclic Carbene)-Metal Complexes for Cavity-Dependent Catalysis." Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066380/document.
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Des complexes de Cyclodextrine (CD)-NHC-Métaux (NHC= Carbènes N-Hétérocycliques), comprenant des métaux tel que AgI, CuI et AuI ont été synthétisés. Une étude structurale a mis en évidence la position intra-cavitaire du métal, induisant des interactions C-H…M, C-H…X et π…X. L’influence du type de cavité (α-, β-, γ-CD) et du type de dérivés NHC (Imidazole, benzimidazole, triazole) a été étudiée. Les interactions diminuent avec l’augmentation de la taille de la cavité et en parallèle, celles-ci ont été amplifiées avec des dérivés NHC possédant un effet donneur plus fort. Les complexes de cuivre correspondants montrent une bonne réactivité pour la réaction d’hydroboration des alcynes. Il a de plus été observé que la sélectivité est dépendante de la taille de la cavité. En effet, alors que le complexe α-CD-Cu donne le produit linéaire, le complexe β-CD-Cu oriente vers la formation de l’isomère branché. Les espèces CD-Cu potentiellement impliquées dans le cycle catalytique ont été étudiées. Deux mécanismes différents sont ainsi proposés. Dans la réaction catalysée par le complexe α-CD-Cu, le processus catalytique a lieu en dehors de la cavité; tandis que lorsque la cavité est plus grande (β-CD) la catalyse a lieu à l’intérieur de la celle-ci. Par ailleurs, les complexes ont également montré une différente énantiosélectivité et régiosélectivité dans une réaction de cycloisomerization catalysée par des comlexes dor, en fonction de la taille de la cavité de ces catalyseurs. Les résultats catalytiques ont prouvé que les complexes CD-NHC-Métaux fonctionnent comme des catalyseurs pour lesquels la taille de la cavité influe sur la séléctivitéCyclodextrin (CD)-NHC-Metal complexes (NHC=N-Heterocyclic Carbene), including the AgI, CuI and AuI complexes were synthesized. A structural study showed that the metal was inside the cavity, and induced by C-H…M, C-H…X and π…X interactions. Variations on α-, β-, γ-CD cavities and NHC derivatives (midazole, benzimidazole, triazole) were studied. When the size of the cavity increased, these interactions decreased. Furthermore, stronger σ-donating effects lead to stronger interactions. CD-Cu complexes showed good activity in catalytic hydroboration of alkynes. The selectivity is depending on the size of the cavity of the catalyst. α-CD copper complex gives linear hydroboration products, while β-CD copper complex yields the branched isomers. The CD-Cu species potentially involved in the catalytic cycle were studied, two different mechanisms were thus proposed. In the α-CD-Cu complex catalyzed reactions, the catalytic process takes place outside the cavity; while a bigger cavity β-CD permits the catalysis to take place inside the cavity. Furthermore, the gold complexes also show different enantioselectivity and regioselectivity in cycloisomerization using different cavity-based catalysts. Catalytic results evidenced the selectivity of a catalytic reaction is dependent on the cavity of the CD-NHC-metal complexes
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Taweepreda, Wirach. "Studies of inclusion complexes of polymer and cyclodextrins." Thesis, University of Bristol, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.420918.
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Ivanov, Anton Andreevich. "Supramolecular association of metal clusters with cyclodextrins : from interactions in solution to the design of mixed systems clusters-polyoxometalates." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLV095/document.
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Les travaux de cette thèse intitulée « Associations supramoléculaires des Complexes de clusters métalliques avec les cyclodextrines : Des interactions en solution à la conception de systèmes mixtes Clusters-polyoxométallates » portent sur l’encapsulation de clusters octaédriques par des oligosaccharides cycliques appelés cyclodextrines. La première partie de ce travail concerne l’étude en solution aqueuse du comportement de clusters de rhénium cationiques [Re6Q8(H2O)6]2+ (avec Q = S ou Se) ou anioniques du type [Re6Q8(CN)6]4- (avec Q = S, Se ou Te) vis-à-vis de cyclodextrines de type α, β et γ. Les études menées en solution au moyen de la RMN de 1H montrent que les clusters aquo cationique [Re6Q8(CN)6]4- interagissent très faiblement avec la cyclodextrine γ (noté γ -CD) alors que la diffraction des rayons X révèle que ces systèmes cristallisés contiennent l’adduit supramoléculaire de type hôte-invité de stoichiométrie 1:1 {[Re6Q8(H2O)6]@g-CD}2+ sans que l’analyse structurale ne révèle d’intéractions attractives significatives entre le cluster et le macrocycle. L’étude des dérivés anioniques cyano [Re6Q8(CN)6]4- (Q = S, Se ou Te) a permis d’établir les critères favorisant les interactions de type hôte-invité. Les études en solution montrent que pour ces systèmes cluster-CD, les interactions supramoléculaires peuvent être classés selon l’ordre α-CD < β-CD < γ-CD. Cependant, la nature du ligand chalcogénure (Q = S, Se, Te) a aussi une influence déterminante dans le processus de reconnaissance supramoléculaire en suivant le classement suivant S < Se < Te. Les études RMN 1H, 77Se et 125Te complétées par la détermination par ITC des grandeurs thermodynamiques associées au processus de reconnaissance hôte-invité. Ces études révèlent dans tous les cas que le processus de reconnaissance est très largement favorisé d’un point de vue enthalpique alors que la contribution entropique est toujours défavorable. Cette signature thermodynamique peut être reliée au comportement chaotrope de ces ions en solution. Les études structurales menées par diffraction des rayons X ont dans tout les cas montrées des associations supramoléculaires qui peuvent différer subtilement selon la nature du cluster et le type de cyclodextrine. Enfin, des études électrochimiques confirment les résultats précédents et mettent davantage en lumière le rôle déterminant de la charge ionique sur la stabilité des agrégats supramoléculaires.Ces complexes de rhénium ont été engagés dans des associations inédites avec des polyoxométallates. L’idée sous jacente de cette étude repose sur la création de système « push-pull » inorganiques associant une unité riche en électrons (le cluster) avec unité pauvre en électrons (le POM). Plusieurs structures sont décrites avec l’ion de Dawson [P2W18O62]6- ou un POM géant dérivé des bleus de molybdène. Elles démontrent le rôle déterminant de la cyclodextrine dans le processus d’interaction qui permet d’associer des anions cluster-POM. Ces composés apparaissent comme de très bon candidats pour l’élaboration de phases nanostructurées à base d’oxychalcogénures métalliques.Dans une dernière partie, les travaux ont été étendus aux clusters {M6X8Cl6}2- ( avec M = Mo ou W et X = Br ou I). Bien que certains d’entre eux présentent des propriétés remarquables de luminescence, leur faible résistance à l’hydrolyse en milieu aqueux limite considérablement leur utilisation pour des applications biomédicales. Ce travail réalisé au moyen de la RMN de 35Cl et UV-vis montre que les associations supramoléculaires de type hôte-invité permet de stabiliser de façon spectaculaire ces clusters. Des études préliminaires de cytotoxicité et de photothérapie dynamique (PDT) menées sur certains de ces systèmes cluster-CD montrent des résultats encourageant qui augurent de belles perspectives pour l’avenirIn this work, we report in first part the detailed study of the interaction of rhenium cluster complexes [{Re6Q8}(H2O)6]2+ and [{Re6Q8}(CN)6]4–/3– (Q = S, Se, Te) with cyclodextrins (α, β and γ). Upon dissolving the reagents in water and then evaporating the solution or diffusion of ethanol vapors into the solution, crystalline products were obtained which crystallized as fragments without the formation of host-guest compounds (α-CD and Q = Se, Te ) or inclusion compounds with weak interactions with the primary or secondary face of CD (β-CD and all complexes, γ-CD / α-CD and Q = S), or very tightly coupled inclusion compounds involving the secondary face of CD (γ- CD and Q = Se, Te), which was confirmed by XRD. Moreover, similar behavior was found in aqueous solutions using a wide range of methods such as NMR spectroscopy (both from the host and the guest side), ITC, mass spectrometry, etc. Also, it was demonstrated that the inclusion cyclodextrins strongly affects the properties of cluster complexes, especially redox and luminescent. All data obtained by solution methods lead to the identification of two main factors of interaction with the CD, namely: (1) size-matching of host and guest, (2) the chaotropic nature of the guest. The chaotropic effect (the water structure breaking) of the complexes makes a significant contribution to the formation of inclusion compounds, however, when size-matching is additionally observed, the interaction becomes even stronger. The chaotropic effect was also confirmed by studying two complexes with different charges. Thus, an increase in the chaotropic effect without changing the size of the complex led to an increase in the binding constants with γ-CD by approximately 1000 times.In the second part, we have demonstrated that the inclusion compounds of rhenium cluster complexes with cyclodextrin can be combined with other functional inorganic compounds - polyoxometalates. In such three-component systems, cyclodextrin plays the role of a binding agent. In the case of a logical combination of oppositely charged cationic cluster complexes and a Dawson-type anion, the system is mainly formed due to the strong bond between the POM and the CD, since cluster interacts very weakly with CD. On the other hand, ions of the same charge (anionic cluster and anionic POM) can also form three-component systems, which are mainly based on inclusion of cluster into CD. Moreover, inclusion compounds can participate in the formation of nanoscale supramolecular ensembles with a nano-wheel {Mo154}, which exist both in solid state and in aqueous solution.In the last part, it was demonstrated that, using the supramolecular approach, it is possible to stabilize molybdenum and tungsten cluster complexes with low hydrolytic stability in aqueous solutions. For the first time, water-soluble Na2[{M6X8}Cl6] complexes (M = Mo, W, X = Br, I) were obtained and the kinetics of substitution of terminal ligands in water was studied in detail. Adding γ-CD to the system leads to the formation of strong inclusion compounds in a 1:2 ratio with the participation of the secondary face of cyclodextrin. Moreover, inclusion in γ-CD significantly reduces the rate of substitution of terminal ligands and allows us to obtain solutions that are stable for at least several months. The obtained compounds possess the best photophysical characteristics of luminescence in aqueous solutions among molybdenum and tungsten cluster complexes. Also, inclusion in the CD allowed us to study for the first time the redox properties of complexes in water. In conclusion, it was demonstrated that such systems have the lowest cytotoxicity, which makes them promising for further studies for use in biology and medicine
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Azzi, Joyce. "Amélioration des qualités nutritionnelles et organoleptiques des aliments par encapsulation de composés actifs (arômes, vitamines, antioxydants, acides gras insaturés...)." Thesis, Littoral, 2017. http://www.theses.fr/2017DUNK0460/document.
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L'incorporation d'ingrédients bioactifs dans les produits alimentaires est en plein essor. Il a été démontré que ces ingrédients possèdents des propriétés biologiques importantes permettant l'amélioration de la santé et la prévention des maladies dites de civilisations. Toutefois, l'ajout de ces molécules bioactives est dans la plupart des cas impossible ou insuffisant, du fait que ces composés ne sont que peu solubles dans les systèmes aqueux et présentent i) une stabilité limitée contre les dégradations chimique ou physique, ii) une libération non contrôlée ou une faible biodisponibilité. Face à ces contraintes, les recherches actuelles visent à élaborer des systèmes d'encapsulation efficaces pour résoudre ces problèmes de formulation. Dans notre étude, deux représentants d'ingrédients alimentaires ont été choisi : le sesquiterpène nérolidol (Ner) et le flavonoïde quercétine (Quer) présentant diverses activités biologiques mais des propriétés physicochimiques problématiques. Ainsi, l'objectif de notre travail a été d'encapsuler ces composés actifs dans les cyclodextrines (CDs), les liposomes conventionnels (LCs) et le système mixte cyclodextrine-liposomes (DCLs) afin de développer des systèmes naturels et éco-compatibles ayant des applications potentielles dans les domaines alimentaires.Trois axes ont été abordés. Le premier axe a porté sur la préparation et la caractérisation des complexes d'inclusion CD/invité en solution et à l'état solide. Les techniques de spectroscopie UV-visible, Chromatographie Liquide à Haute Performance (CLHP), Carbone Organique Total (TOC), ¹H Résonance magnétique nucléaire (RMN), 2D ROESY RMN et de la modélisation moléculaire ont été utilisées comme outils pour la caractérisation des complexes obtenus. Des études de phase de solubilité ont également été réalisées. Le deuxième axe a porté sur la préparation des LCs et DCLs par la méthode d'injection éthanolique et leur caractérisation. Les préparations des LCs encapsulant la quercétine a été réalisée à partir de phospholides naturels de jaune d'oeuf (Lipoid E80) et de soja insaturés (Lipoid S100) ou saturés (Phospholipon 90H) afin d'étudier l'effet de la composition lipidique que les caractéristiques des liposomes. La formulation optimale a été par la suite appliquée pour préparer des LCs encapsulant le nérolidol et des DCLs encapsulant les deux molécules. Ce dernier est produit par l'incorporation des complexes d'inclusion HP-β-CD/Ner (à différents rapport moléculaire CD:Ner) et SBE-β-CD/Quer dans la cavité aqueuse des liposomes. Le dernier axe a été orienté vers l'évaluation de l'effet de l'encapsulation sur les propriétés physicochimiques du nérolidol et de la quercétine (libération in vitro, photostabilité, stabilité dans les milieux gastro-intestinales, stabilité de stockage) et leur activité antioxydante. Les résultats ont montré que les CSs ont été capables d'encapsuler les composés actifs étudiés, d'augmenter leur solubilité, leur photostabilité ainsi que leur activité antioxydante. En outre, les liposomes à base de Lipoid E80 ont été trouvés majoritairement de taille nanométrique et ont conféré aux molécules une efficacité d'encapsulation (EE) élevée ainsi qu'une meilleure stabilité par rapport aux deux autres types de liposomes. De plus, la taille des DCLs ains que leur EE ont été prouvées dépendante du rapport moléculaire CD:invité. Par rapport aux LCs, les DCLs ont assuré une libération prolongée du nérolidol, ont augmenté la photostabilité des composés et la stabilité de la quercétine dans les milieux biologiques. Les résultats de cette étude suggèrent que ces systèmes peuvent être considérés comme outils prometteurs pour l'optimisation des formulations alimentaires incorporant le nérolidol et/ou la quercétinePhytochemicals are widely distributed secondary metabolites, divided into three major classes : terpenoids, flavonoids and alkaloids. They are shown to possess important biological properties such as anti-cancer, anti-inflammatory and anti-microbial properties. Therefore, increasing the use of these bioactive molecules in food products may reduce the risk of widespread diseases referred to as "diseases of civilization". However, their low solubility, susceptibility to degradation and their rapid release reduce their bioavailability in the human body and thus their biological effect. To solve the aforementioned physicochemical drawbacks, encapsulation systems were developed to allow the incorporation of phytochemicals in food. In this study, two food ingredients : the sesquiterpene nerolidol and the flavonol quercetin were selected du to their potent biological activities but their problematic physicochemical properties.Therfore, the aim of this work was to encapsulate these molecules into cyclodextrins (CDs), conventional liposomes (CLs) and the double systeme drug-in-cyclodextrin-in-liposomes (DCLs), in order to develop nztural and biocompatible formulations that may find applications in food fields. This project was built around three main research axes. The first part dealt with the preparation and the characterization of CD/guest inclusion complexes both in solution and in solid state. Characterizations were performed with UV-visible spectroscopy, High Performance Liquid Chromatography (HPLC), Total Oragnic Carbon (TOC), ¹H NMR, 2D ROESY NMR, and molecular modeling. These investigations were complemented with phase solubility studies.The second axis addressed the preparation of CLs ans DCLs by ethanol injection method and characterization of the vesicles. CLs encapsulating quercetin were prepared from three different types of phospholipids (Lipoid E80, Lipoid S100, Phospholipon 90H) in order to study the effect of lipid composition on the characteristics of liposomes. The optimal formulation was then selected to prepare nerolidol loaded-CLs and DCLs encapsulating the two compounds. HP-β-CD/Ner (at different CD:Ner molar ratios) and SBE-β-CD/Quer inclusion complexes were used as the aqueous phase in the DCL system. The last part focused on the effect of encapsulation on the physicochemical properties of nerolidol and quercetin (in vitro release, photostability, stability in gastro-intestinal fluids, storage stability) and their antioxidant activities. Results demonstrated that CDs could successfully encapsulate bioactive compounds, enhance their solubility , photostability and antioxidant activity. Furthermore, Lipoid E80-liposomes were nanometric in size, exhibited a high entrapment efficiency and higher stability in comparison to the other formulations. Moreover, CD:guest molar ratio influenced the size of DCLs and their encapsulation efficiency. When compared to CLs, DCLs extended the release of neridol, enhanced the photostability of both compounds ans increased the stability of quercetin in biological fluids. These results could be considered as a promising tool to achieve an optimized and efficient formulation incorporating nerolidol and quercetin in food industry
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Pembouong, Gaëlle. "Caractérisation de polymères supramoléculaires hiérarchiques à base de cyclodextrines fonctionnalisées." Thesis, Sorbonne université, 2018. http://www.theses.fr/2018SORUS005/document.
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Les systèmes moléculaires de taille nanométrique sont impliqués dans une grande variété de procédés et de fonctions biologiques. La compréhension des mécanismes permettant le contrôle de leur structure à plusieurs échelles présente un grand intérêt. Par exemple, malgré le défi que cela représente, il n'existe actuellement aucun système synthétique permettant la formation d'objets fibrillaires de diamètre monodisperse et modulable en milieu aqueux. L'objectif de ce travail est de développer une boite à outils moléculaires de cyclodextrines (CDs) sélectivement di-fonctionnalisées de façon à pouvoir s'auto-assembler sous forme de fibres pouvant ensuite s'associer pour former des assemblages hiérarchiques via des interactions secondaires. L'étude de la formation du premier niveau d'assemblage de ces composés par viscosimétrie, ITC et SANS a montré que l'utilisation de CDs pontées permet de favoriser la polymérisation de ces composés en supprimant le phénomène d'auto-inclusion. Cette étude a permis de développer deux polymères supramoléculaires (PSM) cationiques à base de ?-CDs fonctionnalisées possédant un degré de polymérisation plus élevé que ceux existant actuellement. Leur capacité à former des PSM hiérarchiques en présence de polyanions rigides a ensuite été évaluée par analyses DLS, spectroscopie et cryo-MET. Dans des conditions de concentration en CDs et de rapport en charges optimisées, trois différents assemblages hiérarchiques solubles dans l'eau ont été formés. Nous avons montré que le premier niveau d'association ainsi que la directionnalité des interactions secondaires étaient des paramètres clés pour la formation d'assemblages hiérarchiques stables et de morphologies bien définies. Ces structures modulables nous serviront donc de plateformes pour étudier et mieux comprendre les mécanismes impliqués dans la formation des assemblages hiérarchiquesMolecular systems with nanometer-sized dimensions are involved in a wide variety of processes and biological functions. Understanding the mechanisms controlling their multi-lengthscale structure presents a major interest. For instance, despite this challenge, there is so far no reliable synthetic system forming well-defined tunable fibrillar objects with a monodisperse diameter in aqueous solution. The aim of this work is to develop a tool box of di-functionalized cyclodextrins (CDs) specifically designed to self-assemble into supramolecular rods that could then reach higher levels of hierarchy via interactions mediated by the secondary functionalization. The study of the first level of association of these compounds by viscosimetry, ITC and SANS showed that the use of bridged CDs allows the polymerization by suppressing the self-inclusion phenomenon. As a result, we developed two tunable cationic supramolecular polymers (SMP) based on functionalized β-CD with relatively high polymerization degrees. Their ability to form hierarchical SMP with rigid polyanionic species was then assessed by DLS, spectroscopy and cryo-TEM. In optimized concentration and charge ratio conditions, three different water-soluble hierarchical assemblies were formed. We showed that the first level of association and the high directionality of the secondary interactions are key parameters to achieve these stable, well-defined, hierarchical assemblies. These tunable structures will be therefore used as a platform to get greater insight into hierarchical assembling processes
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Churamani-Poulenc, Rebecca. "Assemblages supramoléculaires de cyclodextrines fonctionnalisées comme outil de transfection." Electronic Thesis or Diss., Sorbonne université, 2024. http://www.theses.fr/2024SORUS078.
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La thérapie génique est un domaine scientifique crucial qui doit être davantage développé, et la crise du Covid-19 n'a fait que confirmer cette nécessité. Les virus sont connus pour être des vecteurs de matériel génétique très efficaces. Parmi eux, le virus de la mosaïque du tabac (TMV), dont le manteau protéique peut s'auto-assembler en un co-assemblage coopératif avec de l'ARN, a inspiré notre groupe pour concevoir un virus artificiel à base de cyclodextrines (CDs). Notre groupe a synthétisé une CD cationique portant un pont ammonium et sur le côté duquel est fonctionnalisé un groupement adamantyle (CD 1). Il a été démontré que cette dernière est capable de s'auto-assembler en un polymère supramoléculaire. Puis, le groupe a montré que la CD 1 pouvait induire la transfection de siARN.[1] Pour comprendre son mode d'assemblage, nous avons étudié le mélange CD 1 et ADN double brin 18-mère par Cryo-EM. Etonnamment, nous avons observé que de longues et fines fibres se formaient. Nous avons ensuite montré que ces fibres contenaient de nombreuses molécules d'ADN qui sont entourées de CD 1 auto-assemblées, une organisation qui rappelle celle du TMV. Dans ce travail, nous avons aussi montré que des architectures identiques sont observées avec différentes tailles d'ADN simple brin ou double brin. Cependant, nous avons montré qu'avec de l'ADN simple brin, les fibres prenaient plus de temps à se former et nous avons pu suivre leur mécanisme d'assemblage par cryo-EM. De plus, nous avons étudié différents paramètres en termes de pH, de ratios CD/ADN, de tampons et de concentrations des composés, et avons pu optimiser le système et en apprendre plus sur ce dernier. Incroyablement, un léger changement de structure de la CD 1 pour la CD 2 où l'unité adamantyle est maintenant placée au centre de la cavité de la CD entraîne un changement drastique de l'architecture du co-assemblage : des tubes sont obtenus à la place des fibres. Aussi, nous avons découvert que la construction de ces tubes suit un chemin d'assemblage multi-étapes que nous avons suivi et élucidé par des expériences de cinétique en cryo-EM. Nous avons aussi montré que ces tubes pouvaient se former avec de l'ADN simple ou double brin. Afin d'appliquer notre système à la transfection d'ARNm, nous avons ensuite synthétisé une série d'analogues aux CD 1 et 2, en modifiant leurs propriétés de lipophilie et d'auto-assemblage. Nous avons évalué leur capacité à transfecter de l'ARNm in vitro, mais malheureusement aucune efficacité n'a été observée. Pour résoudre ce problème et appliquer notre système à la transfection d'ARNm, nous avons conçu une nouvelle génération de CD s'auto-assemblant et avons prouvé que certaines d'entre elles pouvaient effectivement transfecter de l'ARNm dans des cellules. Nous avons aussi montré que des CDs analogues mais auxquelles nous avons retiré la propriété de s'auto-assembler en oligomères supramoléculaires ne pouvaient pas transfecter l'ARNm. C'est donc la coopérativité entre l'auto-assemblage des CDs par effet hydrophobe et entre les interactions électrostatiques de ces dernières avec l'ARNm qui permet la transfection. Finalement, nous avons commencé la synthèse d'analogues de ce hit afin d'améliorer l'efficacité de transfection et la viabilité cellulaire et avons obtenu des premiers résultats prometteurs. [1] Evenou P., Rossignol J., Pembouong G., Gothland A., Colesnic D., Barbeyron R., Rudiuk S., Marcelin A-G., Ménand M., Baigl D., Calvez V., Bouteiller L., Sollogoub M., Angew. Chem. Int. Ed. 2018, 57, 7753-7758. PCT/EP2016/070892, 5th september 2016, WO/2018/041377, 8th mars 2018Gene therapy is a crucial scientific field we must further develop, and the Covid-19 crisis only confirmed it. Viruses are known to be highly effective genetic material vectors. Among them, the tobacco mosaic virus (TMV) whose coat proteins can self-assemble in a cooperative hierarchical co-assembly with RNA, inspired our group to design a synthetic artificial virus based on cyclodextrins (CDs). Our group synthesized a cationic adamantyl-functionalized CD (CD 1) where the adamantyl is borne by an ammonium bridge and demonstrated its ability to self-assemble into a supramolecular polymer. They we showed that CD 1 could induce transfection of siRNA.[1] To understand its mode of assembly, we studied the CD 1/DNA mixture by Cryo-EM. To our surprise and delight, we found that very long thin fibers were formed. We further proved that they contain many copies of double stranded DNA 18-mer, which are surrounded by self-assembled CD 1, a structure highly reminiscent of TMV. In this work, we also proved that identical architectures are observed with different sizes of single and double stranded DNA. However, we proved that with single stranded DNA, the fibers take longer to build, and we discovered and followed its mechanism of assembly by cryo-EM. Moreover, we studied different parameters in terms of pH, CD/DNA ratios, buffers, concentrations and we have optimized our system and learnt more about the behavior of our assemblies. Amazingly, a slight change of structure of CD 1 into CD 2, where the adamantyl group is positioned in the center of the cavity induces a drastic modification of the co-assembly architecture: tubes were obtained instead of fibers. Besides, we found out that the construction of those tubes follows a multi-steps pathway that have been elucidated by cryo-EM kinetics experiments. We also showed that same tubes can be formed with ssDNA or dsDNA and with different size of DNAs. We then developed a series of analogues of CD 1 and CD 2, tuning their lipophilicity and self-assembling properties. We evaluated the capacity of CD 1 and CD 2 and their analogues to transfect mRNA in vitro. Unfortunately, no transfection was observed. Because of the lack of mRNA transfection efficiency with these CDs, we designed a new generation of self-assembling CDs and proved that some of them, indeed, transfect mRNA into cells. We also proved that CDs which cannot self-assemble are not able to deliver mRNA and that we need cooperativity between the CDs' hydrophobic interactions, allowing the supramolecular oligomers formation, and the electrostatic interactions between the CDs and the mRNA to transfect. Finally, we started to synthetize analogues of this hit to improve transfection efficiency and cell viability and got promising results. [1] Evenou P., Rossignol J., Pembouong G., Gothland A., Colesnic D., Barbeyron R., Rudiuk S., Marcelin A-G., Ménand M., Baigl D., Calvez V., Bouteiller L., Sollogoub M., Angew. Chem. Int. Ed. 2018, 57, 7753-7758. PCT/EP2016/070892, 5th september 2016, WO/2018/041377, 8th mars 2018
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Dubald, Marion. "Development of antibiotic-based ophthalmic preparations for the treatment of local infections." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSE1201.
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Depuis ces dernières décennies, l'administration ophtalmique est devenue une voie privilégiée des molécules en vue d'une action locale. La sécurité, l'efficacité et l'acceptabilité de ces médicaments imposent une formulation stérile et facilement applicable pour l'amélioration de l'observance du patient. L'objectif de ce travail a été de développer une forme ophtalmique topique efficace, facilement applicable et contenant un principe actif (PA) d'intérêt. Les études d'encapsulation du PA dans des particules de polymères en vue de sa protection mettent en évidence la difficulté de formuler des vecteurs avec un PA hydrosoluble. Son instabilité en solution aqueuse a été démontrée lors des études de stabilité et a orienté le choix galénique vers des préparations semi-solides. L'absence, ou la faible quantité d'eau présente, améliore la stabilité du PA. L'association des cyclodextrines dans la formulation montre une nette stabilisation du PA dans les préparations semi-solides. Les études de caractérisation de ces formes mettent en évidence la stabilité du PA dans une pommade hydrophobe et dans une émulsion en présence de cyclodextrine. De plus, les essais de microbiologie démontrent l'intérêt de l'utilisation d'une émulsion dans l'efficacité de la forme pharmaceutique contre Staphylococcus aureus. Les formes ophtalmiques mise au point présentent un intérêt majeur dans le traitement d'infections oculaires localisées en remplacement des thérapeutiques actuellement sur le marchéOver the last few decades, ophthalmic administration has become a preferred route for molecules for local action. The safety, efficacy and acceptability of these drugs require a sterile and easily applicable formulation for improved patient compliance. The objective of this work was to develop an effective, easily applicable topical ophthalmic form containing a drug of interest. Studies of the encapsulation of API in polymer particles for protection show the difficulty of formulating vectors with a water-soluble API. The instability of the drug in aqueous solution has been demonstrated in stability studies and guided galenic choice to semi-solid preparations. The absence, or small amount of water, improves the stability of the API. The association of cyclodextrins in the formulation shows a marked stabilization of the drug in semi-solid preparations. Characterization studies of these forms demonstrate the stability of the drug in a hydrophobic ointment and in an emulsion in the presence of cyclodextrin. Moreover, microbiological tests demonstrate the advantage of using an emulsion in the efficacy of the pharmaceutical form against Staphylococcus aureus. The ophthalmic forms developed are major interest in the treatment of localized eye infections in place of the therapeutics currently on the market
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Antoniuk, Iurii. "Elaboration de nanoparticules auto-assemblées par interaction hote-invité." Thesis, Paris Est, 2016. http://www.theses.fr/2016PESC1082/document.
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Ce travail de thèse concerne le développement de nouvelles architectures hôte et invité à base de polysaccharide et leur application dans la conception de nanoparticules molles à structure hiérarchique et d’hydrogels supramoléculaires pour l’encapsulation et la libération de médicaments. Dans la première partie du manuscrit, nous décrivons une voie de synthèse de polymères hôtes et invités comprenant des chaînons espaceurs poly(éthylène glycol) hydrophile (PEG) entre le squelette de dextrane et soit le groupement b-cyclodextrine (bCD)(polymère hôte) ou le groupement adamantane (Ada) (polymère invité). La présence des bras espaceurs PEG a conduit à une amélioration substantielle de la disponibilité des groupes Ada du polymère invité par rapport à la situation avec un bras espaceur court et hydrophobe. Nous avons ensuite étudié la formation de nanoassemblages entre les différents types de polymères hôtes et invités. Une fois de plus, les espaceurs PEG ont eu un impact significatif sur la taille et la structure interne des nanoassemblages. La deuxième partie de ce travail décrit la synthèse d’une nouvelle série de dextranes greffés par des chaînons PEG et Ada, préparés par réactions de cycloaddition d'azoture-alcyne catalysées le cuivre (I) (CuAAC). Les degrés substitution (DS) en chaînons PEG greffés (5000 g/mole) sont de l’ordre de 20 mol.% tandis que les DS par les groupements Ada sont variés de 0 à 10 mol.%. L’affinité de ces polymères pour la bCD native, ainsi que leur capacité à former des couches superficielles avec des polymères de b-cyclodextrine (pbCD et pbCDN+), s'avèrent dépendre fortement du DS en groupements Ada, ce qui résulte de la coopérativité des interactions impliquées. Dans la dernière partie, nous avons décrit une stratégie de modification non covalente de microgels sensibles à la température à base de poly (N- isopropylacrylamide) (pNIPAm), pour les recouvrir d’une couronne de pbCDN+. Cette stratégie s'appuie sur l’auto-assemblage électrostatique entre pbCDN+ et les chaînes de poly(acide acrylique) chargés négativement (pAAc) et greffées à la surface des microgels. Dans le cas d’une charge globalement neutre des microgels pNIPAm/bCDN, la stabilisation colloïdale a pu être réalisée à l’aide de dextranes greffés (PEG, Ada) en utilisant une procédure d’assemblage hiérarchique. Enfin, à l'aide de dextrane modifié par des groupements Ada (DT-Ada), les microgels pNIPAm/bCDN ont pu être associés pour produire des hydrogels 3D hiérarchiques (10wt %). Leur température de transition sol-gel est décalée vers le bas pour atteindre la gamme des températures physiologiques (37-41°C) par rapport à celle observée dans un hydrogel hôte-invité uniforme bCDN/DT-Ada (51°C)This PhD work is based on the development of new architectures of polysaccharide-based host and guest polymers and their application in the design of hierarchically structured soft nanoparticles and supramolecular hydrogels with interesting drug delivery profiles. In the first section of the manuscript we describe a synthetic pathway to host and guest polymers with hydrophilic poly(ethylene glycol) PEG spacer between the dextran backbone and either b-cyclodextrin (bCD) host or adamantane (Ada) guest grafted groups. The presence of the PEG spacer led to a substantial improvement of the availability of Ada groups of the guest polymer as compared to its counterpart, where Ada are linked to the backbone with a short hydrophobic spacer. This was followed by the study of nanoassemblies formation between the different types of host and guest polymers. Once again, PEG spacer had a significant impact on the size and internal structure of the resulting nanoassemblies. The second part of this work describes synthesis of a series of new (PEG, Ada)-grafted dextrans prepared by copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC). The degrees of substitution (DS) by PEG grafts (5000 g/mole) are close to 20 mol% while the DS by Ada-groups are varied from 0 to 10 mol.%. The affinity of these polymers to monomeric bCD, as well as their ability to form superficial layers with b-cyclodextrin polymers (pbCD, pbCDN+), are strongly dependent on the DS by Ada, giving an indication of cooperativity effects between them. In the last part we described a strategy to a non-covalent modification of thermoresponsive poly(N-isopropylacrylamide) (pNIPAm)-based microgels with a pbCDN+ host polymer shell. It uses on electrostatic self-assembly between pbCDN+ and negatively charged poly(acrylic acid) (pAAc) chains grafted to the surface of microgels. The resulting pNIPAm/bCDN microgels with neutral overall charge could be colloidally stabilized with (PEG, Ada)-grafted dextrans via a hierarchical self-assembly procedure. Finally, using Ada-modified dextrans (DT-Ada), pNIPAm/bCDN microgels could be physically cross-linked to yield hierarchical 3D hydrogels (at 10 wt%). Their gel-sol transition temperature is shifted down to the physiological temperature range (37-41°C) as compared to uniform pbCDN/DT-Ada host-guest hydrogels (51°C
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Burusco, Goñi Kepa Koldo. "Methodological Approach to Conformational Search. A Study Case: Cyclodextrins." Doctoral thesis, Universitat Autònoma de Barcelona, 2009. http://hdl.handle.net/10803/3296.
Full textAbstract:
No és difícil trobar exemples que mostrin la inqüestionable importància de la estereoquímica en temes com la salut o l'economia: D'una banda, la quiralitat és tristament ben coneguda a causa del desastre de la Talidomida. Per altra banda, varem trobar recentment un altre exemple no menys important dins el camp de les conformacions de macromolècules: La Malaltia de Creutzfeld-Jacob. Per això, creiem que és rellevant examinar amb més detall aquells temes relacionats amb els estudis conformacionals.A la present Tesi Doctoral es proposa un procés en dues etapes per a estudiar espais conformacionals de macromolècules mitjançant Simulated Annealing (SA) i Dinàmica Molecular (DM). Ambdues metodologies són ben conegudes dins el camp de la Modelització Molecular; no obstant això, la principal contribució aportada per aquest treball és el desenvolupament d'eines metodològiques millorades -descriptors moleculars adequats, anàlisi de saturació de conformacions i grau de solapament de trajectòries- per mesurar quantitativament l'evolució i convergència dels càlculs SA i MD.
No es difícil encontrar ejemplos que muestren la incuestionable importacia de la estereoquímica en temas como la salud o la economía: Por una parte, la quiralidad es tristemente bien conocida debido al desastre de la Talidomida. Por otra parte, encontramos recientemente otro ejemplo no menos importante dentro del campo de las conformaciones de macromoléculas: La Enfermedad de Creutzfeld-Jacob. Por ello, creemos que es relevante examinar más detenidamente aquellos temas relacionados con los estudios conformacionales.
En la presente Tesis Doctoral se propone un proceso en 2 etapas para estudiar espacios conformacionales de macromoléculas mediante Simulated Annealing (SA) y Dinámica Molecular (DM). Ambas metodologías son bien conocidas dentro del campo de la Modelización Molecular; sin embargo la principal contribución aportada por este trabajo es el desarrollo de herramientas metodológicas mejoradas -descriptores moleculares adecuados, análisis de saturación de conformaciones y grado de solapamiento de trayectorias- para medir cuantitativamente la evolución y convergencia de los cálculos SA y MD.
It is not difficult to find examples that show the unquestionable importance of stereochemistry in human life and economy: On the one hand, chirality is unfortunately the most well known one due to the Thalidomide Disaster. On the other hand, there is a no less important example in recent years in the field of molecular conformations: the Creutzfeldt-Jakob Disease. In this sense, we think that it is worth paying more attention to conformational studies due to their indisputable relevance.
A 2-stage process for studying Conformational Spaces of large macromolecules involving Simulated Annealing (SA) Conformational Search followed by series of Molecular Dynamics (MD) calculations is proposed in this PhD Thesis. Both methodologies are well-known ones in the Molecular Modelling area of knowledge; nevertheless, the main contribution made by this research work is the development of enhanced methodological techniques -suitable molecular descriptors, saturation analysis and trajectory overlapping ratio- for monitoring quantitatively how SA and MD calculations evolve.
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Mokhtar, Mohd Noriznan. "Biocatalytic Production, Preparation and Characterization of Large-ring Cyclodextrins." Doctoral thesis, Universitätsbibliothek Chemnitz, 2009. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-200900431.
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Cyclodextrins (CD) are cyclic oligosaccharides composed of six to more than sixty
glucose units. Large-ring cyclodextrins (LR-CD) are novel CD comprised of more than eight
glucose units with cavity structures and sizes different from that of commercially available
CD6 – CD8. LR-CD may offer unique molecular recognition properties and can be produced
biocatalytically from starch using cyclodextrin glucanotransferase (CGTase, E.C. 2.4.1.19) in
a short reaction time. LR-CD were isolated from glucose, CD6 – CD8 and other compounds by
complexation of CD6 – CD8 as well as precipitation techniques. The yield of LR-CD (degree
of polymerization from 9 to 21) was optimized using central composite design. Addition of
polar organic solvents to the synthesis resulted in higher yields of LR-CD. LR-CD composed
of 9 to 21 glucose units were successfully separated using reversed-phase of ODS-AQ
chromatography and normal-phase of polyamine II chromatography. Maintaining optimized
reaction conditions aided in a high yield of CD9; it could be separated with reasonable yield
using a single step of polyamine II chromatography. A co-grinding method helped to obtain
higher solubilization levels of glibenclamide, vitamin A acetate and vitamin D3 in CD13, CD10
and CD11, respectively when compared to other CD. Vitamin K1 was solubilized in distilled
water with CD6 – CD13 using a co-precipitation method. When compared with other CD, CD9
was seen to be the best solubilizer. The analysis of complexes using ESI MS showed
spironolactone and glibenclamide complexed with CD9 and CD13, respectively.
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Ghadiali, Delna. "Aminolysis of the 4-acetoxybenzoate anion catalysed by cyclodextrins." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0020/MQ54292.pdf.
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El-Hadad, Omar. "Effects of Cyclodextrins on the Kinetics of Emulsion Polymerisation." Thesis, University of Canterbury. Chemistry, 2009. http://hdl.handle.net/10092/4013.
Full textAbstract:
Cyclodextrins (CD) are semi-natural oligosaccharides composed of a number of D-glucose units. They are produced from renewable resources, and have been found to be of catalytic effect for the emulsion polymerization of many monomers. Using monomers whose emulsion polymerization kinetics have been thoroughly studied, this research analyses the effect of CD on the entry and exit rate coefficients for the emulsion polymerization of styrene, and the entry and termination rate coefficients for the emulsion polymerization of MMA.
Throughout the course of the work, CD was found to have a positive impact on the polymerization rate of styrene in a polystyrene latex stabilized with a cationic surfactant. Furthermore, the exit rate coefficient for this latex was found, via γ-relaxation experiments, to increase in proportion to the styrene solubility in water, exactly as predicted by theory. Of itself this would lead to a decrease in reaction rate. That there is still an overall increase in the reaction rate in the presence of CD is because of a quite strong effect on entry rate coefficients. Again, this is consistent with the prevailing theory for entry, that of Maxwell and Morrison, which says that increased aqueous phase solubility of monomer will lead to faster entry.
Intriguingly, experiments done on a polystyrene latex stabilized with an anionic surfactant showed a different effect for CD: γ-relaxation experiments found very little effect of CD on exit rate, and chemically initiated experiments found the same for overall rate. This is consistent with CD having little effect on aqueous phase styrene solubility, which in fact is what direct measurements via UV-visible spectroscopy indicated. It is speculated that the anionic surfactant was successfully competing with styrene to occupy the CD cavities. On the other hand, measurements suggested that styrene successfully competes with cationic surfactant, which is consistent with kinetic results.
Experiments of the above nature were then carried out with methyl methacrylate (MMA), a more water soluble monomer than styrene and one with emulsion polymerisation kinetics of a different nature (so-called pseudo-bulk). γ-relaxation experiments found no effect of CD on termination rate coefficients, exactly as one would expect given that termination is an intra-particle reaction whereas CD exists in the aqueous phase. However the same experiments also revealed an unexpected effect of CD on entry: the thermal entry rate coefficient was found to increase markedly in the presence of CD. It seems likely that this unusual effect stems from interaction of products of γ radiolysis with CD.
Results for chemically-initiated polymerization of MMA were inconclusive. Under some conditions there was actually retardation in the presence of CD, which is actually consistent with measurements of MMA solubility in water, which suggested a slightly negative effect of CD. However it is hard to explain such a phenomenon. Further, under other conditions it was found that CD either had no effect on chemically-initiated rate or could even increase it slightly. The only safe conclusion at this stage is that CD has no major effect on MMA kinetics, which arguably is consistent with MMA being relatively water soluble: intuitively one would expect that CD is most useful (‘catalytic’) for the EP of monomers of low solubility.
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Faiz, Jonathan Antony. "Directional molecular wires constructed from photo- and electroactive cyclodextrins." Thesis, University of Birmingham, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.419740.
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Boodhoo, Kishore. "Functionalised cyclodextrins for multi-metallic assemblies : towards metal extraction." Thesis, University of Birmingham, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.273554.
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Shankland, N. "B-cyclodextrins : Characterisation and use in topical semi-solids." Thesis, University of Strathclyde, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382494.
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Tahanpesar, Elham. "Studies of the synthesis of cyclodextrins with novel stereochemistry." Thesis, Cardiff University, 2007. http://orca.cf.ac.uk/54588/.
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Proton-deuterium exchange of the carbinol hydrogens of gluco-, manno- and galacto-methyl- ot-D-pyranosides with deuterium oxide catalysed by ultrasonicated Raney nickel had low regioselectivity. 4,6-0-Benzylidene-methyl-cc-D-glucopyranoside underwent deuteration at C- 2 and C-3 and cleavage of the benzylidene group, whereas 4,6-O-isopropylidene-methyl-a-D- glucopyranoside was deuterated exclusively at C-2 (2H-NMR), which provides a rapid and economical route to 2- 2Hi -methyl-a-D-glucopyranoside. The diol moiety of 4,6-0-benzylidene-methyl-a-D-glucopyranoside was cleaved under aqueous (sodium periodate), and non-aqueous (periodic acid) conditions to give a D-erythritol in high yield (80%, 90%). Application of similar conditions to heptakis{6-0-tert- butyldimethylsilyl)-p-cyclodextrin failed to give an isolable product. The epoxides methyl 2,3-anhydro-4,6-(9-benzylidene-methyl-a-D-mannopyranoside and /z67ta£w(2,3-anhydro)-f3-cyclomannin were prepared via the C2-tosylates. Both reacted with 4-ter/-butylbenzylthiol at the 3-position. The cyclomannin gave an adduct with xQ&,-altro stereochemistry as determined by NMR and the homogeneity was established by MALDI-MS (M+K+, m/z 3109.5, Ci6iH26602sS7Si7K). The mannopyranoside similarly reacted with L- cysteine to give a 4Ci-a//ro-amino acid sugar adduct, but the cyclomannin failed to react. The benzylidene-, isopropylidene- glucopyranosides and the silylated cyclodextrin mentioned above underwent allylation with allyl bromide, to give 2,3-di-O-allyl-glucopyranosides and heptakis(2,3-di-0-allyl)-p-CD respectively. Ring closing metathesis (RCM) with Grubb's 2nd generation catalyst of the allylated cyclodextrin yielded a complex mixture, but the allylated glucopyranosides yielded the cyclo-octenes, which were hydrogenated. Unexpectedly, the benzylidene protecting group was partially cleaved during RCM. All NMR spectra were assigned by correlation methods.
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Dodds, Devric Reginald. "Physicochemical study of inclusion of drug molecules in cyclodextrins." Doctoral thesis, University of Cape Town, 1999. http://hdl.handle.net/11427/9721.
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Includes bibliographical references.Inclusion of drug molecules in cyclodextrins can significantly improve various aspects of their performance and has resulted in the use of cyclodextrins (CDs) for a wide variety of pharmaceutical applications. Consequently, the cyclodextrin inclusion of drugs has received great interest in the pharmaceutical and chemical fields. For this study the inclusion of nine pharmaceutical drugs with CDs was investigated in the solid state. The objectives of the study were i.) the preparation, ii.) determination of the chemical composition, iii.) analysis of thermal behaviour and iv.) investigation of the solid state features of the complexes. Ultraviolet spectrophotometry, elemental analysis and thermogravimetric analysis were the principal techniques used for determination of composition. Hot stage microscopy, differential scanning calorimetry and thermogravimetric analysis were the principal techniques used for the analysis of thermal behaviour. Single crystal x-ray diffraction and x-ray powder diffraction were the principal techniques used for investigation of structural features. This thesis reports the preparation by crystallisation from solution of eight beta cyclodextrin (β-CD) and four gamma cyclodextrin (γ-CD) inclusion complexes with selected drugs as guests, as well as the determination of their chemical compositions and analysis of their thermal behaviours. Investigation of the structural features of these complexes includes the determination of the crystal structures of five β-CD complexes and one γ-CD complex. The preparation of hydnoxypropyl-β-CD complexes by kneading and co-grinding is also reported.
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Pais, Joana Margarida Mosquito. "Cyclodextrins inclusion to stabilise multicomponent guests of plant origin." Master's thesis, Universidade de Aveiro, 2017. http://hdl.handle.net/10773/22418.
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Mestrado em Bioquímica - Bioquímica AlimentarA inclusão em ciclodextrinas (CDs) de hóspedes multi-componente, tais como óleos essenciais e extratos de plantas, é um tema atual e útil para uma série de aplicações nas indústrias alimentar, cosmética e farmacêutica. No presente trabalho foram estudados dois destes sistemas, tendo por hóspedes o óleo essencial de Cistus ladanifer e uma mistura de gingerois extraídos de rizoma fresco de gengibre. A composição do óleo essencial de C. ladanifer foi estudada por GC-MS, tendo-se identificado 94,3% dos seus componentes e determinado a massa molecular aproximada em 143,7 g.mol-1. O óleo foi usado para formar complexos de inclusão com as ciclodextrinas beta e gama. A identificação dos componentes do óleo incluídos preferencialmente em cada CD foi feita por extração com clorofórmio e análise por GC-MS, tendo-se observado inclusão preferencial de compostos de maior peso molecular na ciclodextrina beta, enquanto a ciclodextrina gama incluiu compostos de menor peso molecular. Os complexos de inclusão foram analisados no estado sólido por espectroscopia de infravermelho (FTIR), {1H} 13C CP-MAS RMN e difração de raios X de pós (PXRD), postulando-se empacotamento em canal para ambos os complexos. A mistura de gingerois, obtida a partir de gengibre fresco por maceração em acetona e purificação em coluna, foi analisada por 1H RMN e espectrometria de massa (ESI-QTOF), contendo 54,05 % de 6-gingerol, 19,45% de 8-gingerol e 26,5 % de 10-gingerol, a que corresponde uma massa molecular de 314,7 g.mol-1. O complexo γ-CD·gingerois, obtido por co-precipitação, foi caracterizado por FTIR, {1H} 13C CP-MAS RMN, DSC e PXRD. Também neste caso foi observado o empacotamento em canal. Por um ajuntamento segundo Pawley, foi possível refinar os parâmetros de célula em a = b = 23,886(3) Å e c = 23,356(3) Å (tetragonal). A atividade antioxidante de γ-CD·gingerois foi estudada pelo ensaio de proteção do β-caroteno, tendo-se obtido resultados similares aos dos gingerois não incluídos. Os gingerois e o γ-CD·gingerois foram usados para preparar iogurte fortificado com 1% (m/m) de gingerol (ou equivalente de complexo) tendo-se verificado que o complexo é mais facilmente disperso na matriz do que os gingerois não encapsulados. A cor do iogurte fortificado com γ-CD·gingerois apresentou-se mais semelhante à do iogurte simples enquanto para o iogurte com gingerois registaram maiores diferenças. Os iogurtes fortificados foram ainda estudados quanto à durabilidade, não se tendo observado alterações de pH nem aparecimento de odores desagradáveis durante quatro semanas, enquanto no iogurte simples a formação de odor se iniciou entre a segunda e a terceira semana. A atividade antioxidante dos iogurtes fortificados medida pelo método de ABTS foi superior à do controlo, sendo a condição mais promissora verificada para a amostra com gingerois. Estes resultados sugerem que a matriz interfere com a atividade antioxidante de γ-CD·gingerois.
Cyclodextrin inclusion of multi-component guests such as essential oils and plant extracts is a current topic of research. These systems are usefull for a number of applications in food, cosmetic and pharmaceutical industries. The present work focus on two of these systems, having as guests Cistus ladanifer essential oil and a mixture of gingerols obtained from fresh ginger rhizome. The C. ladanifer essential oil composition was elucidated by GC-MS, which allowed identifying 94.3 % of the components and to establish the approximate Mw at 143.7 g.mol-1. The oil was subsequently included into beta and gamma cyclodextrins (β and γ-CDs) by co-precipitation. Identification of the included components of the oil was done by chloroform extraction followed by GC-MS analysis. β-CD preferentially included compounds of higher molecular weight, whereas γ-CD included lower molecular weight compounds. Solid state analysis of the inclusion complexes comprised infrared spectroscopy (FTIR), {1H} 13C CP-MAS RMN and powder X-ray diffraction (PXRD) that suggests the occurrence of channel packing for both. Gingerols were obtained from fresh ginger by maceration in isopropanone followed by column chromatography. The product was analysed by 1H RMN and mass spectrometry (ESI-QTOF), revealing a composition of 54.05 % 6-gingerol, 19.45 % 8-gingerol and 26.5 % 10-gingerol, and a corresponding Mw of 314.7 g.mol-1. The γ-CD·gingerols complex was obtained by co-precipitation and characterized by FTIR, {1H} 13C CP-MAS RMN, DSC and PXRD. It presented the typical γ-CD complexes packing in the form of infinite channels. PXRD data was further treated with a Pawley extraction allowing to identify a tetragonal unit cell with the parameters refined at a = b = 23.886(3) Å e c = 23.356(3) Å. The antioxidant activity of γ-CD·gingerois and free gingerols, as evaluated by the β-carotene bleaching assay, showed similar potencies. Free gingerois and the complex of γ-CD·gingerols were employed in fortification of yoghurt, at a concentration of 1% (m/m) of gingerol (or its equivalents mass for the complex). A better dispersion into the matrix was observed for the γ-CD·gingerols–fortified yogurts in comparison with gingerols-fortified samples. The colour of the yoghurts fortified with the complex was almost similar to that of plain yoghurt, whereas those fortified with free gingerols had more colour variation in regard to plain yoghurt. The storage stability of fortified yoghurts was evaluated through pH monitoring and the formation of malodours. No changes in pH or malodours were observed for four weeks. In turn, a malodour in simple yoghurt was noticed starting from the second to the third week of storage. The antioxidant activity of yoghurts, as measured by the ABTS assay, revealed a higher antiradical action for gingerols-fortified and γ-CD·gingerols–fortified yogurts when compared to that of plain yogurts, with the most promising results being registered for the gingerols-fortified samples. These particular results suggest that food matrix might interfering the antioxidant activity of γ-CD·gingerols.
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Cooper, Andrew Donovan. "Resolution of enantiomers using cyclodextrins in NMR and HPLC." Thesis, University of Bath, 1991. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.292808.
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Kluzek, Monika. "Lipid membrane alteration under exposure to alpha-cyclodextrins and pH-responsive pseudopeptide polymers." Thesis, Strasbourg, 2017. http://www.theses.fr/2017STRAE045/document.
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Le développement de nanotransporteurs basés sur des lipides, des polymères et des nanoparticules avec des propriétés «sur mesure» pour augmenter l’efficacité de médicaments, fait l’objet de recherches intensives. Toutefois, la physico-chimie subtile des intéractions polymères-lipides and nanoparticules-lipides présente encore de larges domaines mal compris et de nombreuses questions sans réponse. Ce projet de recherche doctoral utilise des techniques de visualisation (Cryo-MET, LSCM), et de caractérisation (ITC, DSC, SAXS, SANS, QCM-D) avancées pour obtenir des informations nouvelles sur les mécanismes d’interaction entre des Cyclodextrines-α d’autre part, des polymères sensibles au pH d’autre part, et des bicouches modèle de DOPC. La forte influence de ces deux composés sur ces systèmes modèle élucide certains aspects relatifs à la toxicité vis-à-vis des membranes biologiques et suggère de nouvelles approches pour des applications pharmaceutiquesThe primary goal of nanomedicine is to improve clinical outcomes. To this end, the development of nanocarriers based on lipids, polymers and nanoparticles with tailor-made properties that enhance the in vivo potency of drugs is a subject of intense research. However, the subtle physical-chemistry of the polymer-lipid and nanoparticle-lipid interactions still present many poorly understood fields of investigation as well as unanswered questions. This doctoral research project utilizes state-of-the-art visualization (Cryo-TEM, LSCM) and characterization (ITC, DSC, SAXS, SANS, QCM-D) techniques to gain novel insights into the interaction between α-Cyclodextrins in the first hand, a pH-responsive polymer in the other hand, and model DOPC bilayers. The strong influence of both compounds on these model systems elucidate some aspects regarding biological membrane toxicity and suggests novel strategies for pharmaceutical applications
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Anil, Gunaratne D. M. "Physical and chemical modification of some cereal, tuber and root starches and the roles of{221}-cyclodextrin as a starch modifyingagent." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2006. http://hub.hku.hk/bib/B37752753.
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Ndlebe, Vuyelwa Jacqueline. "Thermal and photostability studies of triprolidine hydrochloride and its mixtures with cyclodextrin and glucose." Thesis, Rhodes University, 2004. http://hdl.handle.net/10962/d1005052.
Full textAbstract:
Triprolidine hydrochloride (C₁₉H₂₂N₂.HCl.H₂O) (TPH) is a well-known antihistamine drug. It melts between 118°C and 122°C and the amount of water present is 4.5 mass percent. TPH is reported as being photosensitive and must be stored in sealed, light-tight containers. The thermal stabilities of TPH and of 1:1 molar and 1:1 mass ratio physical mixtures of TPH with beta-cyclodextrin (BCD) and with glucose have been examined using DSC, TG and TG-FTIR, complemented by X-ray powder diffraction (XRD) and infrared spectroscopic (IR) studies. Thermal studies of the solid TPH/BCD mixtures indicated that interaction between the components occurs and it is possible that the TPH molecule may be least partially accommodated in the cavity of the BCD host molecule. XRD results support this indication of inclusion. The results for mixtures of TPH/glucose also suggest that there is interaction between the two components. The results of molecular modelling suggest that TPH is most likely to be accommodated in the BCD cavity as a neutral triprolidine molecule with the toluene portion of the molecule entering first. There is also an indication that the Z-isomer should be accommodated slightly more readily than the E-isomer. Photostability studies were done by irradiating thin layers of solid samples of TPH and its mixtures for various times at 40°C using an Atlas Sun test CPS lamp operating at 550 W h m⁻². An analytical method using HPLC was developed and validated to determine the amounts of any photodegradants. DSC, TG, FTIR, XRD and IR were also used examine the irradiated samples. XRD results showed that changes in the TPH crystal structure occurred during irradiation and that these changes increased with the time of irradiation. Irradiation for 20 hours with UV or exposure to sunlight showed the presence of degradants. The results obtained illustrate the general stability of TPH, especially in the solid state. Although the potential for isomerization to the pharmaceutically inactive Z-isomer exists, this transformation would require extreme light conditions. The study has also shown TPH to be compatible with both glucose and BCD, which are potential excipients both in solid and liquid dosage forms. The presents of these excipients in dosage forms will thus not adversely affect the stability and the therapeutic efficacy of TPH. . An analytical method using HPLC was developed and validated to determine the amounts of any photodegradants. DSC, TG, FTIR, XRD and IR were also used examine the irradiated samples. XRD results showed that changes in the TPH crystal structure occurred during irradiation and that these changes increased with the time of irradiation. Irradiation for 20 hours with UV or exposure to sunlight showed the presence of degradants.
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Gramage-Doria, Rafael. "Large cavity cyclodextrin-based macrocyclic ligands : synthesis, coordination and catalytic properties." Phd thesis, Université de Strasbourg, 2012. http://tel.archives-ouvertes.fr/tel-00767168.
Full textAbstract:
Cyclodextrins (CDs) are cyclic oligosaccharides of various sizes containing several α-(1→4)-linked D-(+)- glucopyranose units. The commercially available ones comprise six, seven or eight glucose units, named respectively α-CD, β-CD and γ-CD. Their truncated cone-like and well-defined cavity are particularly attractive for the encapsulation of a variety of substrates. As such, they found numerous applications in many areas of chemistry. A recent development, from which the present work is inspired, consisted in covalently linking transition metals to CD cavities in order to perform and study catalytic reactions in a confined environment featuring steric repulsive or attractive noncovalent interactions with the substrate or/and the metal coordination sphere.The first part of this thesis focuses on reviewing transition metal-based cavitands, for which the first and second metal coordination spheres are controlled by their cavity-shaped ligand. The following chapters are concerned with the synthesis, coordination and catalytic properties of two new phosphane ligands built on a large β-CD scaffold. The first one, named WIDEPHOS, is a diphosphine having two phenylphosphinidene "PPh" units capping adjacent glucose units on a methylated β-CD. This ligand features two phosphorus lone pairs pointing to the cavity interior but not aligned. These geometrical features, combined with the large distance separating the two phosphorus atoms, promote the formation of "imperfect" trans-chelate complexes in which the metal centre swings about the ligand. This unprecedented molecular movement, christened "oschelation", allows each phosphorus atom to form an optimal bond in turn with the coordinated d8 and d10 transition metal ions. Further studies on WIDEPHOS proved that it is better suited for coordinating dinuclear fragments within the confinement of the large β-CD cavity. Severe steric constrains on the metal first sphere of coordination result in the formation of single μ-chlorido bridged dinuclear species. In this new type of square planar complexes, non-optimal orbital overlapping measured by the so-called tilt angle was also found to take place for one of the phosphorus atom together with an "oschelation" movement involving non identical donor atoms, namely a phosphorus and an oxygen atom. Static gold(I) dinuclear complexes displaying similar imperfect orbital overlapping for one of the phosphorus atom were also prepared.
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Kaliappan, Raja. "Selectivity in Photochemical Reactions within Water Soluble Calixarenes and Cyclodextrins." Scholarly Repository, 2008. http://scholarlyrepository.miami.edu/oa_dissertations/31.
Full textAbstract:
The research work presented in this thesis is a consolidated report of experiments aimed at controlling the product selectivity in photochemical reactions. Water soluble hosts such as p-sulfonato calix[n]arenes (n= 6 or 8) and cyclodextrins have been used to solubilize organic molecules in water and to control the product selectivity. These host molecules control the product selectivity by their ability to encapsulate and interact with guest molecules. Furthermore, carrying out reactions in water as solvent is important from green chemistry point of view.