Tesis sobre el tema "Crosslinking chemistry"
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1
Sisson, Thomas Michael 1966. "Crosslinking polymerization in supramolecular assemblies". Diss., The University of Arizona, 1997. http://hdl.handle.net/10150/282566.
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Supramolecular assemblies are composed of noncovalently associated molecules which organize in water to yield 2-D and 3-D architectures. Crosslinking polymerization of supramolecular assemblies provides an effective means to modify their chemical and physical properties. Two methods of characterizing crosslinked polymeric assemblies were developed. These techniques rely on experimentally observed changes in polymer solubility and assembly stability in the presence of nonionic surfactants. The results show an inefficient crosslinking mechanism in organized media compared to isotropic polymerization. Two models rationalizing the inefficient crosslinking observed in organized media were proposed. Symmetrical crosslinking agents were synthesized to test the models. These results suggest intramolecular memorialization is an important process in the efficiency of crosslinking. The polymerization of a heterobifunctional lipid with two polymerizable groups in the same acyl chain separated by a six carbon spacer yielded a novel linear ladder-like polymer architecture. The two reactive groups are in regions of different polarity allowing for the simultaneous, selective, and sequential polymerization depending on the initiation chemistry employed. A second heterobifunctional lipid was designed and synthesized with a longer spacer between the two reactive groups. Polymerization of vesicles gave stable polymeric vesicles. The results from the crosslinking and redox polymerization studies on 2-D assemblies were applied to the inverted hexagonal and bicontinuous cubic phases. Phase behavior is characterized before and after crosslinking polymerization principally by variable temperature ³¹NMR. γ-Initiated polymerization of bis-lipids was studied to evaluate their sensitivity to ionizing radiation. The reactive moiety effects the initial rate of polymerization, extent of polymerization, and inhibition by oxygen. A preliminary investigation of polymerizable ion-paired amphiphiles (IPA) showed polymerization methods commonly used for zwitterionic lipids can be applied to IPA. This is the first report of polymerization of reactive groups in the anionic acyl chain of an ion-paired amphiphile.
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Briceno, Garcia Ruben Dario. "Crosslinking of ethylene copolymers from epoxy chemistry". Thesis, Lyon, INSA, 2014. http://www.theses.fr/2014ISAL0037.
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La plupart des couches d'isolation de câbles pour la moyenne tension "MV" et haute tension "HV" sont fabriquées en polyéthylène réticulé (XLPE) par voie peroxyde. L'impact des sous-produits de réaction sur les propriétés et la nécessité d'une étape de dégazage au cours du processus sont les principaux problèmes liés à cette technologie. Cette étude se concentre sur le développement d'une méthode de réticulation alternative sans les problèmes liés aux sous-produits. Des copolymères d’éthylène/époxy ont été réticulés thermiquement en utilisant un agent aminoacide pour créer des liaisons covalentes entre les fonctions époxydes. L’influence de différents paramètres sur la cinétique de réaction tels que la température de réticulation, les proportions aminoacide/époxy, la taille des particules de l’aminoacide et la teneur en époxy dans les copolymères a été étudiée par techniques de caractérisation telles que : rhéologie dynamique, spectrométrie FTIR, microscopie à balayage électronique et calorimétrie différentielle. En outre, l'étude de la structure du réseau avant et pendant un vieillissement thermique a été effectuée par différentes techniques (mesures de gonflement, spectroscopie FTIR, propriétés de traction et thermoporosimétrie) sur deux types de réseaux : un pré-contraint et un autre non-contraint. Enfin, une caractérisation des propriétés électriques par spectroscopie diélectriques et mesures de claquage électrique a été faite. Les résultats concernant les cinétiques de réaction, les propriétés thermomécaniques et le comportement électrique ont montré que la formulation développée dans cette étude peut être utilisée pour une application de câbleMost of insulation layers of cables for medium voltage “MV” and high voltage “HV” applications are made of crosslinked polyethylene (XLPE) by peroxide technology. The impact of reaction by-products on properties and the consequential need of a degassing stage during the process are the main problems related to this technology. This study focuses on the development of an alternative crosslinking method without by-products issues. Epoxy-ethylene copolymers were thermally crosslinked by using an amino-acid agent to create covalent cross-links between epoxide functions. Influence of several parameters on kinetic reactions such as crosslinking temperature, amino acid/epoxy proportions, size particle of amino acid and epoxy content in copolymers were studied by characterization techniques such as: dynamic rheology, FTIR spectrometry, SEM microscopy and differential calorimetry. In addition, study of the network structure before and during a thermal aging was done on a pre-constrained and a non-constrained network by different techniques (swelling ratio measurement, FTIR spectroscopy, tensile properties and thermoporosimetry analysis). Finally, a characterization of electrical properties by dielectric spectroscopy and breakdown measurements was done. Results related to reaction kinetic, thermo-mechanical properties and electrical behavior have shown that the developed formulation can be used for cable application
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Chiu, Yuen-Yuen. "Experimental and theoretical analysis of free radical crosslinking polymerizations /". The Ohio State University, 1994. http://rave.ohiolink.edu/etdc/view?acc_num=osu148785841798507.
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Budd, Michael E. "Exploiting thermally-reversible chemistry for controlling the crosslinking of polymer networks". Thesis, University of Reading, 2016. http://centaur.reading.ac.uk/63177/.
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High explosives are highly sensitive to accidental detonation by impact, fire, shrapnel and small arms fire. This sensitivity can be reduced by storing the energetic material within a rubbery polymer matrix and are known as plastic bonded explosives (PBX). The current procedure used to manufacture PBX involves mixing the energetic material with a hydroxy-functionalised aliphatic polymer. Upon the addition of an isocyanate crosslinker an immediate polymerisation occurs and thus the rapidly curing mixture must be used to fill the missile or shells, referred to as ‘stores’. This process can lead to poor distribution of the crosslinker resulting in the formation of an inhomogeneously crosslinked matrix and the formation of voids. One solution to this problem involves containing the crosslinker within polyurethane microcapsules that are uniformly dispersed in the explosive-polymer mixture. Upon the application of a stimulus the crosslinker can be released from the microcapsules and the formation of a uniformly crosslinked PBX achieved. Herein is reported the design and synthesis of polyurethane microcapsules that release isocyanate crosslinkers when desired using a thermal stimulus. This has been achieved by exploiting the thermally-reversible nature of oxime-urethane and Diels-Alder adducts that have been incorporated into the shell wall of the microcapsules. An alternative approach to controlling the polymerisation of PBX materials has also been achieved using thermally-reversible blocked isocyanates that regenerate the isocyanate crosslinker when exposed to heat.
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Bilgen, Mustafa. "Wrinkle Recovery for Cellulosic Fabric by Means of Ionic Crosslinking". NCSU, 2005. http://www.lib.ncsu.edu/theses/available/etd-04202005-140912/.
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When treated with formaldehyde-based crosslinkers, cellulosic fabrics show improved mechanical stability, wrinkle recovery angles and durable press performance, but N-methylol treatment also causes fabrics to lose strength and later to release formaldehyde, a known human carcinogen. We have discovered that ionic crosslinks can stabilize cellulose using high or low molecular weight ionic materials which do not release hazardous reactive chemicals, but at the same time provide improved wrinkle recovery angles as well as complete strength retention in treated goods. We have varied polyelectrolyte, the ionic content of fabrics, and various features of the application procedure to optimize the results and to develop an in-depth fundamental physical and chemical understanding of the stabilization mechanism.
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D'Ambruoso, Gemma Delcina. "Site-Isolation, Intramolecular Energy Transfer, and Crosslinking in Synthetic Dendritic Quinacridones". Diss., Tucson, Arizona : University of Arizona, 2005. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu%5Fetd%5F1135%5F1%5Fm.pdf&type=application/pdf.
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Pacella, Francesca. "Tuning the crosslinking chemistry for self-healable mucin hydrogel synthesis and application". Thesis, KTH, Skolan för kemi, bioteknologi och hälsa (CBH), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-279301.
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Immune-orchestrating biomaterials that precisely modulate the immune reac-tion to the host could lead the way for improving the implantation outcomein the transplantation field, in comparison to passive biomaterials. The lab-oratory of Dr. Thomas Crouzier has shown hydrogels derived from mucinsare capable of orchestrating the immune response mediated by foreign bodyresponse (FBR), as a result of evading fibrosis. Further, a recent study fromhis group showed sialic acid on mucin hydrogels is essential for the immuno-logical activity of those materials. Mucin glycans transiently activated thendampened macrophages, important orchestrators for material-mediated FBR,in a sialic acid-dependent manner for the majority of cytokines followed. Thematerial properties such as rheological properties, self-healing capacity, andstability, can be governed by the crosslinking chemistry used and have a drasticimpact on the functionalities of the materials. In this project, various cross-linking strategies are applied to tune the hydrogel properties. We show thatthe robust cross-linking formed mucin hydrogels having a 1.5% (wt/v) bettersupported insulin-secreting cells form islet-like organoids, compared to 2.5%mucin hydrogels. We then investigate the self-healing properties of the newmucin hydrogels and their interactions with various cell systems.Immunologiska biomaterial som specifikt modulerar en immunologisk reak-tion hos värden kan vara vägen till att förbättra resultatet av en transplantationi jämförelse med att använda passiva biomaterial. Inom laboratoriet lett av Dr.Thomas Crouzier har det kunnat påvisas att hydrogels erhållna från mucinerär kapabla till att förändra en immunlogisk respons, Foreign Body Respon-se (FBR) vilket resulterat i att kringgå fibrosis. Utöver detta har ytterligareen studie utförts av hans grupp vilken kunde påvisa att sialinsyra på mucinhydrogel är essentiellt för den immunologiska aktiviteten för dessa biomateri-al. Mucin glykaner aktiveras tillfälligt för att dämpa bildandet av makrofager,vilket är viktigt vid biomaterial FBR i ett sialinsyra-beroende för bildandet avmajoriteten av cytokiner. Materialegenskaperna såsom reologiska egenskaper,självläkande kapacitet, och stabilitet kan regleras genom en krosslänkad kemisom har en drastisk impakt för funktionen för biomaterialen. I detta projekt, ärflera krosslänkande strategier tillämpade för att förstå egenskaperna för hyd-rogelerna. Vi har kunnat påvisa att robusta krosslänkande system av mucinhydrogel bestående av 1.5% (wt/v) ger bättre support till insulin sekreterandeceller att bilda islet liknande organider, att jämföra med 2.5% mucin hydrogel.Vi undersöker sedan den självläkande egenskaperna av nya mucin hydrogeleroch deras interaktioner med ett flertal olika cellsystem.
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Fan, Chengkai. "A New Crosslinking Method of Isobutylene-isoprene Copolymer". University of Akron / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=akron1555686149937045.
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Xing, Liwen. "UV-Triggered and Thermo-Induced Crosslinking of Polymers Containing 1-Functionalized Benzocyclobutenes". University of Akron / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=akron1491396556917182.
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Savin, Rémy. "Catechol chemistry for biosensor manufacturing : synthesis and electro-crosslinking of gold nanoparticles/enzymes". Thesis, Strasbourg, 2022. http://www.theses.fr/2022STRAE008.
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L’intérêt pour les bioélectrodes croît exponentiellement depuis plusieurs dizaines d’années. En particulier, les biocapteurs et les biopiles enzymatiques ont montré des performances intéressantes pour la surveillance in-situ de biomarqueurs d’intérêts ou pour l’alimentation électrique de dispositifs miniaturisés bio-implantés. Malgré la multitude d’applications envisagées, ces dispositifs peinent encore à se généraliser sur le marché à cause de plusieurs limitations majeures. Le coût, la facilité de fabrication, la sensibilité et surtout la stabilité dans le temps sont des paramètres encore à améliorer. Etant des limitations intrinsèques au choix et à l’organisation des matériaux constituant la couche sensible, nous avons proposé par ce travail une nouvelle voie de fabrication des bioélectrodes. Nous avons utilisé un mélange de polyphénol, sel d’or, médiateur électrochimique et enzyme (relative au biomarqueur d’intérêt) qui a ensuite été électro-réticulés en complexes enzymes/nanoparticules organisés. Enfin, nous avons généralisé ce concept sur membrane souple avec co-immobilization du médiateur ce qui constitue une approche originale dans le développement de pansements intelligents pour le suivi des plaies chroniquesInterest in biosensors has grown exponentially in recent decades. In particular, enzymatic biosensors and biofuel cells have shown great promises as in-situ monitoring of interesting biomarkers or as miniaturized bio-implanted powering devices. Despite the multitude of applications, these devices are struggling to widespread on the market due to several limitations. Cost, ease of fabrication, sensitivity and stability over time are parameters that still deserve to be improved. The choice and spatial organization of the materials within the sensitive layer need to be reconsidered in order to propose new strategies for bioelectrodes manufacturing. In this work, a simple mixture of polyphenol, gold salt, electrochemical mediator and enzyme (related to the biomarker) were electro-crosslinked into an organized enzymes/nanoparticles film. Finally, this concept was transferred onto a flexible membrane with co-immobilization of the mediator. This original approach has enhanced to develop smart chronic wound dressings
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Yeats, Keith. "An investigation into the synthesis and crosslinking of some polymers containing cyclopropyl groups". Thesis, Durham University, 1990. http://etheses.dur.ac.uk/6051/.
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The thesis describes an investigation into the use of polymers containing cyclopropyl groups as network forming materials. The initial route investigated involved the synthesis and homopolymerization of novel acrylate and methacrylate monomers containing cyclopropyl groups. Preliminary crosslinking experiments revealed the unsuitability of this approach. The second route examined involved the synthesis of a series of all hydrocarbon copolymers containing pendant cyclopropyl groups. Crosslinking experiments using a variety of initiators demonstrated the feasibility, in principle, of the proposed network forming system. In order to provide a practical crosslinking system further investigation into suitable initiators would be required.
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Vaghjiani, Jeetendra Dhanji. "Effect of crystallisation and crosslinking conditions on the catalytic properties of crystalline enzymes". Thesis, University College London (University of London), 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.271642.
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Ogunniyi, David. "Hexamethylene-N,N' bis (tert-butyl peroxycarbamate) as a crosslinking agent for elastomers". Thesis, Loughborough University, 1985. https://dspace.lboro.ac.uk/2134/25499.
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The synthesis of a new bisperoxycarbamate based on a reaction between hexamethylene-1,6 diisocyanate and tertiary butyl hydroperoxide was undertaken. In addition, studies were carried out on an earlier research bisperoxycarbamate based on methylene bis(4-cyclohexylisocyanate) and tertiary butyl hydroperoxide. The equation showing the preparation of the new material is shown below: [Equation not shown] The new material - hexamethylene-N,N' bis (tertiary butyl peroxycarbamate) is shown to be able to crosslink a wide range of elastomers, namely -BIIR, NR, SBR, NR/BR, CR, FKM, NBR, Q, ECO, GPO. However, it has been found to give best results in fluorocarbon rubber which was examined in further detail. The material is shown to be versatile by using it to cure different grades of fluorocarbon rubber (mainly copolymers of vinylidene fluoride and hexafluoropropylene). The physical properties obtained with the new material as curing agent are comparable with those obtained using standard crosslinking agents for fluoroelastomers. Since carbon dioxide is evolved when bisperoxycarbamates are heated, calcium hydroxide was included in most formulations to act as an absorber system. Calcium oxide and magnesium oxide were found to be suitable metallic oxides to react with any acidic gases (such as hydrogen fluoride) evolved during curing of fluoroelastomer compounds. It was ii observed that the state of cure was- poorer when lead oxides were used (e.g. litharge PbO); also, the use of dibasic lead phosphite as acid acceptor appeared to interfere with HBTBP cure. Compounding studies, solvent extraction methods and nitrogen tests, and crosslink density measurements were used to postulate possible routes of crosslink formation. These routes of crosslink formation were based on homolytic decomposition of the bisperoxycarbamate, radical abstraction, interaction of a reactive intermediate, and radical-radical interaction. Additional information was obtained from stress relaxation measurements which indicated that new crosslinks were formed during postcuring of fluorocarbon vulcanizates and that this process continued in the initial stages of heat-ageing of postcured FKM vulcanizates.
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Mirous, Brian K. "SYNTHESIS AND PRESUMPTIVE CROSSLINKING OF STIMULI-RESPONSIVE DIBLOCK POLYMER BRUSHES". University of Akron / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=akron1144783034.
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Hutson, Leslie K. "Synthesis of Benzoxazoles Containing Allyl Crosslinking Sites via Claisen Rearrangements". Wright State University / OhioLINK, 1999. http://rave.ohiolink.edu/etdc/view?acc_num=wright974400715.
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Amrutkar, Ajay Ramesh. "Synthesis of Polymer Nanoparticles using Intramolecular Chain Collapse and Benzocyclobutene Chemistry". University of Akron / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=akron1493932026567946.
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Mair, Vincent Timotheo. "Synthesis, characterization, and printing of biocompatible click chemistry double network hydrogel". Thesis, Queensland University of Technology, 2022. https://eprints.qut.edu.au/230502/1/Vincent%20Timotheo_Mair_Thesis.pdf.
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Current biomaterial-based approaches for cartilage repair are unable to provide the mechanical characteristics required for healthy joint function. This thesis examines the development of mechanically robust hydrogel biomaterials formed by two interpenetrating polymer networks as a potential avenue for functional cartilage repair.
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Reilly, Meghan J. "Enhancing the mechanical properties of a peptide-based hydrogel via covalent crosslinking". Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 56 p, 2008. http://proquest.umi.com/pqdweb?did=1605146941&sid=4&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Thesis (M.Ch.E.)--University of Delaware, 2008.Principal faculty advisors: Joel P. Schneider, Dept. of Chemistry & Biochemistry; and Eric M. Furst, Dept. of Chemical Engineering. Includes bibliographical references.
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Iyer, Rajkumar Siva. "Levuglandin E2: Dehydration, rearrangement, pyrrole-forming, and protein crosslinking reactions". Case Western Reserve University School of Graduate Studies / OhioLINK, 1991. http://rave.ohiolink.edu/etdc/view?acc_num=case1059487504.
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Shakari, Patrick. "Irreversible strengthening of gelatin hydrogels by salt-directed polypeptide assembly and covalent crosslinking". Thesis, Uppsala universitet, Institutionen för kemi - BMC, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-384512.
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DAI, ZHENYU. "PROTEIN CROSSLINKING BY THE MAILLARD REACTION WITH ASCORBIC ACID AND GLUCOSE". Case Western Reserve University School of Graduate Studies / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=case1184176746.
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Gao, Yunxiang. "Controlling Laminar Flow in Microfluidic Channels and Covalent Chemistry of Single-Walled Carbon Nanotubes". Ohio University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1281558588.
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Precht, Thea-Luise. "Preparing main group metal clusters from organoaluminium reagents : new possibilities in alkali-activated polymer crosslinking". Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/285495.
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The reactions of carboxylic acids with organoaluminium reagents were studied, which led to the formation of novel aluminium compounds. The reactions of orthofunctionalised derivatives of benzoic acid with trivalent aluminium organyls AlR3, led to the formation of different Al-based molecular clusters, depending on the nature of R, the reaction stoichiometry and the character of the benzoic acid derivative. The obtained compounds were characterised in the solid state by X-ray diffraction methods and two main motifs were observed. When the acid and AlR3 reacted in a one-to-two stoichiometry the obtained products, [iBu4Al2(μ-O2CC6H4-2-μ- O)]2, [(Me2Al)2(μ-O2CC6H4-2-μ-NH)]2, [(iBu2Al)2(μ-O2CC6H4-2-μ-NH)]2, [(Me2Al)2(μ- O2CC6H4-2-μ-NMe)]2 and [(iBu2Al)2(μ-O2CC6H4-2-μ-NMe)]2, consisted of a central distorted 12-membered macrocycle, formed by two [Al-O-C-O-Al-X] units (X= O,N) and was found to be dimeric. The reaction between anthranilic acid derivatives and AlR3 could also take place in a one-to-one ratio. For anthranilic acid and Nmethylanthranilic acid the obtained crystals only allowed a qualitative analysis and showed the structure of the products, [MeAl(μ-O2CC6H4-2-μ-NH)]4, [iBuAl(μ-O2CC6H4- 2-μ-NMe)]4 to be tetrameric and each consisting of a distorted 16-membered ring formed by four [O-C-O-Al] units. With the reaction of N-phenylanthranilic acid it was possible to isolate a structural analogous product [iBuAl(μ-O2CC6H4-2-μ-NPh)]4 which could be fully characterised by x-ray crystallography and NMR spectroscopy. Where the quantity and quality of the obtained product was sufficient, the solution behaviour of the compounds was elucidated by multinuclear and multidimensional NMR spectroscopic techniques. The 27Al NMR showed that the aforementioned aggregates are maintained in solution, which for the 12-membered [Al-O-C-O-Al-N] macrocycle of [(iBu2Al)2(μ-O2CC6H4-2-μ-NH)]2 was confirmed by a NOESY spectrum. The second part of this project focused on the preliminary studies towards the application of aluminium compounds in the crosslinking of guar and carboxymethyl hydroxypropyl guar, which are common additives in hydraulic fracturing. Different commercially available aluminium compounds were tested for their general ability to crosslink the aforementioned polysaccharides, yielding promising results for aluminium lactate, aluminium acetylacetonate and aluminium isopropoxide. For the system comprising aluminium lactate in combination with CMHPG, rheological studies were carried out to determine the viscosity, the viscoelasticity, the shear recovery and the stability towards high temperatures. These sought to evaluate the crosslinking properties of the aluminium additive and to optimise the required conditions of the different system components. Finally, it was possible to obtain first proof-of-concept data suggesting that synthetically obtained aluminium compounds such as [Me2Al(μ- O2CPh)]2 and Al[MeC(CH2O)3]2(AlMe2)3 can be employed for the crosslinking of guar and CMHPG.
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Koeth, Richard A. II. "The Green Functionalization and Crosslinking of Polyisobutylenes for Bioadhesive Employment". University of Akron / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=akron1353178867.
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Bi, Wenzhao. "Part I: Isolevuglandin-protein Cross-linking: Structure and MechanismPart II: Generation and Characterization of a Monoclonal Isolevuglandin[4]E2-protein Adduct Antibody". Case Western Reserve University School of Graduate Studies / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=case1400233239.
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Downey, Jeffrey S. "Precipitation polymerization of divinylbenzene to monodisperse microspheres : an investigation of the particle formation mechanism /". *McMaster only, 2000.
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Lee, Jehoon. "Synthesis, characterization, and applications of the low cross-link density poly acrylate elastomers using direct reversible addition fragmentation chain transfer cross-linker". University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron149798302050725.
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Jadhav, Abhijit V. "Crosslinking of polyaniline with aryl azides and the photolysis of vinyl azides and azidopropanones". University of Cincinnati / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1204666531.
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Chen, Jun. "Transition Metal Complexes of Nucleosides for Cancer Chemotherapy". University of Dayton / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1461516224.
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Song, Cheng Qian. "A study of the shearing and crosslinking of hydroxypropyl cellulose, a liquid crystal polymer, and its permeability as a hydrogel membrane". Case Western Reserve University School of Graduate Studies / OhioLINK, 1991. http://rave.ohiolink.edu/etdc/view?acc_num=case1055946641.
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Lawrence, Patrick G. "Ionically Crosslinked Polymer Networks for Underwater Adhesion and Long-Term Controlled Release". University of Toledo / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1417437994.
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Heffner, Kenneth Henry. "Radiation Induced Degradation Pathways for Poly (Methyl Methacrylate) and Polystyrene Polymers as Models for Polymer Behavior in Space Environments". [Tampa, Fla.] : University of South Florida, 2003. http://purl.fcla.edu/fcla/etd/SFE0000175.
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Nair, Kamlesh Prabhakaran. "Multi-functionalized side-chain supramolecular polymers a methodology towards tunable functional materials /". Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/26505.
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Thesis (Ph. D.)--Chemistry and Biochemistry, Georgia Institute of Technology, 2009.Committee Chair: Weck, Marcus; Committee Member: Breedveld, Victor; Committee Member: Bunz, Uwe; Committee Member: Liotta, Charles; Committee Member: Marder, Seth; Committee Member: Srinivasarao, Mohan. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Tillet, Guillaume. "Utilisation de la réaction de cycloaddition de Huisgen afin d'améliorer les propriétés des polymères fluorés". Thesis, Montpellier, Ecole nationale supérieure de chimie, 2010. http://www.theses.fr/2010ENCM0011/document.
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L'utilisation de la réaction de cycloaddition 1,3 de Huisgen afin d'optimiser les propriétés de polymères fluorés constitue l'objectif de ce travail. Cette cycloaddition a été étudiée selon deux stratégies spécifiques. La première consiste en une cycloaddition, réalisée entre un groupe azidé et une fonction nitrile, non catalysée, tandis que la seconde concerne la cycloadditon, catalysée par le cuivre, entre un groupe azido et une fonction alcyne dont la réaction est classiquement appelée « click chemistry ». Le premier chapitre est consacré à une étude bibliographique sur la réticulation et la post-réticulation chimiques des polymères à température ambiante et à des températures inférieures à 150 °C. Cette étude décrit de façon quasi-exhaustive les différentes réactions chimiques permettant de réaliser une réticulation, et ce en les classant par fonctions clés. Le second chapitre décrit la réticulation d'un élastomère fluoré commercial, porteur de fonction nitrile par cycloaddition 1,3 de Huisgen non catalysée à l'aide d'un agent réticulé fluoré téléchélique bisazidé. Une étude modèle de la réaction de cycloaddition mettant en jeu une réaction nitrile-azide à l'aide de composés moléculaires afin de déterminer les meilleures conditions de réaction. Le troisième chapitre concerne le greffage d'un composé phthalocyanine sur un copolymère fluoré (de type poly(chlorotrifluoéthylène-co-2-iodoethyl vinyl éther) par cycloaddition de Huisgen catalysée au cuivre, ou « click chemistry », dans le but d'obtenir un composé possédant des propriétés photovoltaïques intéressantesThe objective of this work deals with the Huisgen 1.3 cycloaddition reaction to optimize the properties of fluoropolymers. This cycloaddition is investigated using two main strategies. The first one concerns a cycloaddition performed between an azide group and a nitrile function, and non-catalyzed, while the second one is a copper-catalyzed cycloadditon, involving a group azide and an alkyne function and this reaction is conventionally called "click chemistry". The first chapter is devoted to a non-exhaustive literature review on the chemical crosslinking and post-crosslinking polymers carried out at room temperature and at temperatures below 150 ° C. This study describes a list of different chemical reactions to achieve a crosslinking, and that classifying them by key functions. The second chapter describes the crosslinking of commercially available, fluoroelastomer, bearing nitrile groups by 1,3 Huisgen uncatalyzed cycloaddition using a telechelic fluorintaed bisazido crosslinking agent. This chapter exhibits first a model study of the cycloaddition involving a nitrile-azide reaction to determine the best reaction conditions. The third chapter concerns the grafting of an alkyne phthalocyanine compound onto a fluorinated copolymer (poly(chlorotrifluoethylene-co-2-iodoethyl vinyl ether) by 1,3 Huisgen cycloaddition catalyzed by copper, or "click chemistry", to obtain a compound having good photovoltaic properties
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Federico, Stefania. "Synthetic peptides derived from decorin as building blocks for biomaterials based on supramolecular interactions". Phd thesis, Universität Potsdam, 2011. http://opus.kobv.de/ubp/volltexte/2012/5966/.
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In this work, the development of a new molecular building block, based on synthetic peptides derived from decorin, is presented. These peptides represent a promising basis for the design of polymer-based biomaterials that mimic the ECM on a molecular level and exploit specific biological recognition for technical applications.
Multiple sequence alignments of the internal repeats of decorin that formed the inner and outer surface of the arch-shaped protein were used to develop consensus sequences. These sequences contained conserved sequence motifs that are likely to be related to structural and functional features of the protein. Peptides representative for the consensus sequences were synthesized by microwave-assisted solid phase peptide synthesis and purified by RP-HPLC, with purities higher than 95 mol%. After confirming the desired masses by MALDI-TOF-MS, the primary structure of each peptide was investigated by 1H and 2D NMR, from which a full assignment of the chemical shifts was obtained. The characterization of the peptides conformation in solution was performed by CD spectroscopy, which demonstrated that using TFE, the peptides from the outer surface of decorin show a high propensity to fold into helical structures as observed in the original protein. To the contrary, the peptides from the inner surface did not show propensity to form stable secondary structure. The investigation of the binding capability of the peptides to Collagen I was performed by surface plasmon resonance analyses, from which all but one of the peptides representing the inner surface of decorin showed binding affinity to collagen with values of dissociation constant between 2•10-7 M and 2.3•10-4 M. On the other hand, the peptides representative for the outer surface of decorin did not show any significant interaction to collagen.
This information was then used to develop experimental demonstration for the binding capabilities of the peptides from the inner surface of decorin to collagen even when used in more complicated situations close to possible appications. With this purpose, the peptide (LRELHLNNN) which showed the highest binding affinity to collagen (2•10-7 M) was functionalized with an N-terminal triple bond in order to obtain a peptide dimer via copper(I)-catalyzed cycloaddition reaction with 4,4'-diazidostilbene-2,2'-disulfonic acid. Rheological measurements showed that the presence of the peptide dimer was able to enhance the elastic modulus (G') of a collagen gel from ~ 600 Pa (collagen alone) to ~ 2700 Pa (collagen and peptide dimer). Moreover, it was shown that the mechanical properties of a collagen gel can be tailored by using different molar ratios of peptide dimer respect to collagen.
The same peptide, functionalized with the triple bond, was used to obtain a peptide-dye conjugate by coupling it with N-(5'-azidopentanoyl)-5-aminofluorescein. An aqueous solution (5 vol% methanol) of the peptide dye conjugate was injected into a collagen and a hyaluronic acid (HA) gel and images of fluorescence detection showed that the diffusion of the peptide was slower in the collagen gel compared to the HA gel.
The third experimental demonstration was gained using the peptide (LSELRLHNN) which showed the lower binding affinity (2.3•10-4 M) to collagen. This peptide was grafted to hyaluronic acid via EDC-chemistry, with a degree of functionalization of 7 ± 2 mol% as calculated by 1H-NMR. The grafting was further confirmed by FTIR and TGA measurements, which showed that the onset of decomposition for the HA-g-peptide decreased by 10 °C compared to the native HA. Rheological measurements showed that the elastic modulus of a system based on collagen and HA-g-peptide increased by almost two order of magnitude (G' = 200 Pa) compared to a system based on collagen and HA (G' = 0.9 Pa).
Overall, this study showed that the synthetic peptides, which were identified from decorin, can be applied as potential building blocks for biomimetic materials that function via biological recognition.In dieser Arbeit wird das Design, die Synthese und Analyse neuer molekularer Bausteine für Biomaterialien basierend auf synthetischen, von Decorin abgeleiteten Peptiden beschrieben. Diese Peptide sind deshalb als Baustein für polymer-basierte Biomaterialien von besonderem Interesse, da sie die extrazelluläre Matrix (ECM) auf molekularer Ebene nachempfinden und spezifische, biologische wichtige Interaktionen für technische Anwendungen nutzbar machen. Das Alignment multipler Sequenzen der internen Repeats von Decorin, die jeweils die innere bzw. äußere Seite des sichelförmigen Decorins bilden, wurde genutzt, um Konsensus-Sequenzen zu definieren. Diese Sequenzen beinhalten stark konservierte Sequenzmotive, die wahrscheinlich wichtig für Struktur und Funktion des Proteins sind. Ausgewählte Peptide, die repräsentativ für die Konsensus-Sequenzen sind, wurden dann mittels Mikrowellen unterstützter Festphasensynthese synthetisiert und mit RP-HPLC aufgereinigt, so dass Peptide mit Reinheiten ≥ 95 mol% erhalten wurden. Die Peptide wurden per MALDI-TOF-MS sowie 1D und 2D NMR Spektroskopie charakterisiert, wobei die Zuordnung der chemischen Verschiebungen zu einzelnen Protonen und Kohlenstoffen aus den 2D NMR Experimenten erfolgte. In Lösung wurden die Peptide zudem mit CD Spektroskopie untersucht, wobei gezeigt werden konnte, dass nur Peptide, die von der äußeren Seite des Decorins abgeleitet wurden, sich durch Zugabe von 2,2,2-Trifluorethanol zu α-Helices falten. Diese Faltung ist auch in der Röntgenstruktur bei den korrespondierenden Abschnitten zu finden. Im Gegensatz dazu zeigten Peptide, die von der inneren Seite des Decorins abgeleitet wurden, keine stabilen Sekundärstrukturen in Lösung (β-Faltblattstruktur in der Röntgenstruktur). Bindungsstudien der Peptide zu Kollagen I wurden mit Oberflächenplasmonenresonanz durchgeführt, wobei gezeigt werden konnte, dass alle bis auf ein Peptid, die von der innneren Seite abgeleitet wurden, an Kollagen mit Dissoziationskonstanten von 2•10-7 M bis 2.3•10-4 M binden, während Peptide, die für die äußere Seite von Decorin repräsentativ sind, keine Bindung an Kollagen I zeigten. Diese Information wurde genutzt, um experimentelle Demonstrationsobjekte dieser Interaktion in komplexeren, einer späteren Anwendung näheren Situation, zu entwickeln. Dazu wurde das Peptide LRELHLNNN, welches die stärkste Bindung zu Kollagen I zeigte (KD = 2•10-7 M), N-terminal mit einer Alkinbindung funktionalisiert, so dass durch Kupfer (I) katalysierte Reaktion mit 4,4'-Diazidostilben-2,2'-disulfonsäure ein Peptid-Dimer erhalten werden konnte. Rheologische Untersuchungen zeigten, dass durch Zugabe des Peptid-Dimers der Elastizitätsmodul G' von Kollagen-Gelen von ~ 600 Pa (nur Kollagen) auf ~ 2700 Pa (Kollagen und Peptide-Dimer) gesteigert werden konnte. Darüber hinaus konnte gezeigt werden, dass die Veränderung der mechanischen Eigenschaften der Gele durch Veränderung des Kollagen:Peptid-Dimer Verhältnisses angepasst werden konnten. Das gleiche, mit einer Alkin-Bindung funktionaliserte Peptid wurde dann zur Darstellung eines Peptid-Fluorescein Konjugats genutzt, indem es mit N-(5'-azidopentanoyl)-5-aminofluorescein umgesetzt wurde. Eine wässrige Lösung des Peptid-Farbstoff-Konjugats wurde dann in Kollagen- bzw. Hyaluronsäuregele injiziert. Die Diffusion des Peptid-Farbstoff-Konjugats war in Kollagengelen im Vergleich zu Hyaluronsäuregelen deutlich verlangsamt. Das dritte Demonstrationsobjekt wurde erhalten, indem das Peptid LSELRLHNN, welches die geringste Bindung an Kollagen zeigte (KD = 2.3•10-4 M), auf Hyaluronsäure (HA) gegrafted wurde. Die Reaktion wurde durch Carbodiimid-mediierte Kupplung erreicht, und ein Funktionalisierungsgrad von 7 ± 2 mol% wurde durch Integration der 1H-NMR Spektren bestimmt. Das erfolgreiche Grafting wurde durch FTIR- und TGA-Untersuchungen bestätigt. In letzteren wurde gezeigt, dass der thermische Abbau durch das Grafting bei etwas niedrigeren Temperaturen beginnt als der Abbau reiner Hyaluronsäure (ΔT = 10 °C). Rheologische Untersuchungen zeigten, dass ein System aus Kollagen und HA-g-Peptid ein um zwei Größenordnungen höheren Elastizitätsmodul G' hat (G' = 200 Pa) als Systeme, die aus einer physikalischen Mischung von Kollagen und HA bestehen (G' = 0.9 Pa). Zusammenfassend konnte gezeigt werden, dass die Peptide, die von Decorin abgeleitet wurden, als Kollagen-bindende Bausteine für biomimetische Materialien genutzt werden können.
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Charron, Patrick Nelson. "Burst Pressure Properties and Ex Vivo Analysis of Alginate-Based Hydrogels for Tissue Sealant Applications". ScholarWorks @ UVM, 2015. http://scholarworks.uvm.edu/graddis/454.
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Lung diseases, cancers, and trauma can result in injury to the connective tissue lining the lung, i.e., the pleura. Pleural injuries lead to pneumothoraxes or pleural effusions, i.e., air or fluid leaking out of the lung respectively, and potential lung collapse - an immediately life threatening condition. While several bioengineered soft tissue sealants exist on the market, there is only one sealant FDA-approved for use in pulmonary surgery. In addition, very limited techniques are presented in the literature for characterizing the burst properties of hydrogel tissue sealants. For my thesis, I proposed to develop a protocol for characterizing the burst properties of hydrogel sealants using a novel burst pressure test chamber. I further proposed a novel combination of oxidation and methacrylation reactions of alginate for tissue sealant applications, with a particular focus on developing a pulmonary sealant. The proposed research objectives are: 1) To develop protocol for testing hydrogel sealants for soft tissue applications; 2) To verify alginate as a potential for tissue sealant applications; and 3) To optimize an alginate hydrogel sealant and perform ex vivo analysis for a pleural sealant application. Alginate materials with varying degrees of oxidation and methacrylation were synthesized and characterized. Oscillatory rheometry was used to characterize material properties such as viscosity, hydrogel gelation kinetics, and complex moduli. Burst pressure measurements properties and failure mechanisms, i.e. delamination or material failure, were collected for a liquid and dry-state application. Preliminary ex vivo mouse lung model testing demonstrated that methacrylated alginate hydrogels are able to withstand physiological pressures associated with breathing, and failure occurs within the hydrogel for adhesive alginate-based tissue sealants.
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Farhat, Wissam. "Investigation of hemicellulose biomaterial approaches : the extraction and modification of hemicellulose and its use in value-added applications". Thesis, Lyon, 2018. http://www.theses.fr/2018LYSES032/document.
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L'utilisation de matériaux renouvelables est considérée comme l'un des points clés du développement durable. Les glucides sont facilement biodégradables et ont tendance à se dégrader dans les environnements biologiquement actifs. L'hémicellulose (HC) est l'un des polysaccharides les plus courants, représentant environ 20 à 35% de la biomasse lignocellulosique, et n'a pas encore trouvé sa place dans de larges applications industrielles comme la cellulose, autre ressource forestière. L'hémicellulose est un hétéro-polysaccharide. C'est aussi un substitut vert pour les polyols issus du pétrole ainsi qu'un substitut non alimentaire des polyols d'amidon. Les objectifs de ce projet sont le développement d'une stratégie optimisée pour l'extraction de l'hémicellulose et son utilisation dans les biomatériaux à forte valeur ajoutée. L'extraction de l'hémicellulose aurait un grand potentiel comme matière première de la nouvelle bio-économie. Pour étendre ses applications au domaine porteur des hydrogels, comme aux revêtements et adhésifs sensibles aux stimuli, des réseaux de polymères ou des systèmes de relargage de médicaments, les propriétés de l'hémicellulose ont été modifiées en introduisant sur sa chaîne principale des groupes réactifs pour le rendre réticulable réversiblement par la réaction de Diels-Alder. Par cette approche, le potentiel de remplacement des matières premières dérivées du pétrole par des ressources renouvelables pour la production de matériaux polymères biodégradables est important du point de vue sociétal et environnementalThe increased use of renewable materials is considered as one of the key issue of the sustainable development. Carbohydrates are readily biodegradable and tend to degrade in biologically active environments. Hemicelluloses (HC) are one of the most common polysaccharides next to cellulose and chitin, representing about 20-35% of lignocellulosic biomass, and have not yet found broad industrial applications as does cellulose. Hemicellulose is a hetero-polysaccharide and a green substitute for petroleum based polyols and is a non-food-based substitute for starch polyols. The aims of this project are to develop an optimized strategy for the extraction of hemicellulose and the use of the extracted hemicellulose in value-added biomaterials. The extraction of hemicellulose would have great potential to supply raw materials for the new bio-economy. To expand its applications to the field of stimuli-responsive hydrogels, coating and adhesives, polymer networks, as well as drug-delivery systems, the properties of hemicellulose were functionalized by introducing reactive groups onto its main chain to reversibly crosslink it by the Diels-Alder reaction. Hemicellulose based materials were prepared and characterized for their suitable application. Finally, the worldwide potential demand for replacing petroleum-derived raw materials by renewable resources in the production of valuable biodegradable polymeric materials is significant from both social and environmental viewpoints fuel and will predominate in the coming periods
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Meng, Linghui. "Polymer Biomaterial Constructs For Regenerative Medicine and Functional Biological Systems". Case Western Reserve University School of Graduate Studies / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=case1327682278.
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Le, Hel Cindy. "Propriétés et morphologies des thermoplastiques vulcanisés (TPV)". Electronic Thesis or Diss., Lyon, 2021. http://www.theses.fr/2021LYSE1239.
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Les thermoplastiques vulcanisés (TPV) sont des mélanges de polymères présentant à la fois des propriétés d'élasticité et de mise en œuvre et en forme. L'objectif de cette thèse est d'étudier les TPV à base d’un système PP/EPDM malgré la complexité de leurs formulations et de comprendre les mécanismes gouvernant la propriété de recouvrance élastique. La première partie de ce travail s'est concentrée sur l'influence de la chimie de réticulation sur les mécanismes de relaxation aux temps longs des réseaux élastomères réticulés. Il a été constaté que la réticulation radicalaire à partir de la décomposition thermique d’un peroxyde menait à une meilleure recouvrance élastique qu’avec la réticulation avec une résine phénolique. Cependant, la chimie de la réticulation n'est pas le paramètre de premier ordre qui influence cette propriété en ce qui concerne les TPV. En effet, elle dépend surtout de la formulation et du ratio thermoplastique/élastomère, ainsi, leurs influences sur les morphologies finales et sur la déformation rémanente en compression ont été étudiées dans une seconde partie. De plus, l'influence des charges inorganiques a également été étudiée dans les systèmes élastomères avec l'ajout de noir de carbone ou de silice ou dans les systèmes TPV avec l'ajout de noir de carbone. Il a été démontré que l'ajout de noir de carbone dans les systèmes réticulés au peroxyde est bénéfique et améliore les propriétés mécaniques : déformation rémanente après compression et comportement en traction (module d’Young, allongement à la rupture). En effet, la densité de réticulation et la compatibilité entre les polymères ont été améliorées. Enfin, une méthode RMN à bas champ a été utilisée pour l’étude de ces systèmes, notamment avec l'utilisation de la séquence Double Quanta (DQ) qui donne accès aux variations des mobilités moléculaires dans les matériaux avec la mesure du couplage dipolaire résiduelThermoplastics vulcanizates (TPVs) are polymer blends with interesting elasticity and processability properties. The objective of this thesis was to study PP/EPDM TPV despite the complexity of their formulations and to understand what influences the elastic recovery property. The first part of this work was focused on the influence of crosslinking chemistry and its statistics on the long-time relaxation mechanisms of crosslinked elastomeric networks. It was found that radical peroxide crosslinking provides better recovery elasticity than phenolic resin one. However, crosslinking chemistry has been seen to not be the first-order parameter that influences this property for TPV. It depends mostly on the formulation and the thermoplastic/elastomer ratio, their influence on the final morphology and compression set have been then studied in a second part. Moreover, the influence of inorganic fillers was also studied in elastomeric systems with the addition of CB or silica or in TPV systems with the addition of CB. It has been seen that the addition of CB in a system crosslinked with peroxides is beneficial for the improvement in mechanical properties: compression set or tensile test. Indeed, the crosslinking density and the compatibility between polymers were improved. Finally, a low-field NMR method has been applied to these systems, in particular with the use of the Double Quanta (DQ) sequence which gives access to the variations of molecular mobilities in the materials with the measurement of a residual dipolar coupling
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Fogelström, Linda. "Polymer Nanocomposites in Thin Film Applications". Doctoral thesis, KTH, Ytbehandlingsteknik, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-12400.
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The introduction of a nanoscopic reinforcing phase to a polymer matrix offers great possibilities of obtaining improved properties, enabling applications outside the boundaries of traditional composites. The majority of the work in this thesis has been devoted to polymer/clay nanocomposites in coating applications, using the hydroxyl-functional hyperbranched polyester Boltorn® as matrix and montmorillonite clay as nanofiller. Nanocomposites with a high degree of exfoliation were readily prepared using the straightforward solution-intercalation method with water as solvent. Hard and scratch-resistant coatings with preserved flexibility and transparency were obtained, and acrylate functionalization of Boltorn® rendered a UV-curable system with similar property improvements. In order to elucidate the effect of the dendritic architecture on the exfoliation process, a comparative study on the hyperbranched polyester Boltorn® and a linear analogue of this polymer was performed. X-ray diffraction and transmission electron microscopy confirmed the superior efficiency of the hyperbranched polymer in the preparation of this type of nanocomposites. Additionally, an objective of this thesis was to investigate how cellulose nanofibers can be utilized in high performance polymer nanocomposites. A reactive cellulose “nanopaper” template was combined with a hydrophilic hyperbranched thermoset matrix, resulting in a unique nanocomposite with significantly enhanced properties. Moreover, in order to fully utilize the great potential of cellulose nanofibers as reinforcement in hydrophobic polymer matrices, the hydrophilic surface of cellulose needs to be modified in order to improve the compatibility. For this, a grafting-from approach was explored, using ring-opening polymerization of ε-caprolactone (CL) from microfibrillated cellulose (MFC), resulting in PCL-modified MFC. It was found that the hydrophobicity of the cellulose surfaces increased with longer graft lengths, and that polymer grafting rendered a smoother surface morphology. Subsequently, PCL-grafted MFC film/PCL film bilayer laminates were prepared in order to investigate the interfacial adhesion. Peel tests demonstrated a gradual increase in the interfacial adhesion with increasing graft lengths.QC20100621
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Hadrich, Ahdi. "Nouveaux hydrogels à base de polysaccharide obtenus par voie biomimétique ou par photoréticulation". Thesis, Normandie, 2019. http://www.theses.fr/2019NORMR017/document.
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Dans un contexte de démarche écoresponsable et pour répondre aux exigences de biocompatibilité notamment dans les applications cosmétiques et biomédicales, nous avons développé de nouveaux hydrogels à base de polysaccharides neutres et anioniques en utilisant deux voies originales. La 1ère approche est biomimétique et a consisté à mimer un phénomène d’élaboration naturelle d’hydrogels que l’on retrouve chez certains végétaux pour lesquels une enzyme, la laccase, permet de créer des liens de réticulation par dimérisation des composés phénoliques (en l’occurrence de l’acide férulique FA) présents sur les arabinoxylanes des mucilages des graines de céréales par exemple. Notre travail a ainsi consisté à greffer de l’acide férulique via deux chimies différentes de type imidazole et carbodiimide respectivement pour des polysaccharides neutres ou anioniques. Nous avons ainsi fonctionnalisé trois polysaccharides : le pullulane ou PUL (neutre modèle), le carboxyméthylpullulane ou CMP (anionique modèle) et l’acide hyaluronique ou HA (anionique d’intérêt). Des taux de greffage compris entre 2 et 25% ont été obtenus. L’étude physicochimique en régimes dilué et semi-dilué a permis de mettre en évidence un comportement associatif lié au caractère amphiphile des polysaccharides fonctionnalisés. La réticulation en présence de laccase, suivie in situ en rhéologie, a été réalisée avec succès sur les différents systèmes envisagés avec des contrôles possibles de la cinétique, des propriétés mécaniques finales ou encore du gonflement des hydrogels en fonction du caractère neutre ou chargé des polysaccharides, du degré de substitution en acide férulique, de la concentration en polymère ou de l’activité enzymatique fixée. Les dérivés synthétisés ont globalement démontré des activités biologiques (antioxydante et cytocompatible) intéressantes. La deuxième approche repose sur la photoréticulation possible de polysaccharides (PUL, CMP et HA) fonctionnalisés par le greffage d’amine/acide gras mono ou polyinsaturé (oleylamine, acide oléique et linoléique) via la chimie des imidazoles. Si le pullulane modifié par l’acide linoléique à 2% s’est avéré non hydrosoluble en raison de son caractère neutre, tous les autres dérivés avec des taux de greffages de 3 et 10% ont démontré une bonne solubilité dans l’eau. Les études physicochimiques mettent en évidence un très fort caractère associatif de ces dérivés amphiphiles avec la formation de gels physiques en régime semi-dilué. La photoréticulation a été démontrée en rhéologie sous irradiation UV in situ en présence d’un photoamorceur de type Darocur 1173®. Les résultats préliminaires obtenus selon cette approche en photoréticulation ouvrent ainsi des perspectives intéressantesIn the framework of an eco-responsible context and to take advantage of biocompatibility, notably in cosmetic and biomedical applications, we have developed new hydrogels based on neutral and anionic polysaccharides using two original routes. The first approach is biomimetic and consists of mimicking a natural development of hydrogels that is found in certain plants for which an enzyme, laccase, allows to create crosslinks by dimerization of phenolic compounds, in occurrence of ferulic acid (FA) present on arabinoxylans mucilage of cereal seeds for example. Thus, our work consisted in grafting ferulic acid via two different chemical ways that means imidazole and carbodiimide respectively for neutral or anionic polysaccharides. We functionalized three polysaccharides: pullulan or PUL (neutral model), carboxymethylpullulane or CMP (model anionic) and hyaluronic acid or HA (anionic of interest) with grafting rates of between 2 and 25%. The physicochemical study in diluted and semi-diluted regimes evidenced an associative behavior due to the amphiphilic character of the functionalized polysaccharides. The crosslinking in the presence of laccase, followed in situ thanks to rheology, has been successfully performed on the various envisaged systems with possible controls of kinetics, the final mechanical properties or the swelling of the hydrogels as a function of the neutral or charged nature of the polysaccharides, the degree of substitution in FA, the polymer concentration or the enzymatic activity. The synthesized derivatives have generally demonstrated interesting biological activities (antioxidant and cytocompatibility). The second approach is based on the possible photocrosslinking of polysaccharides (PUL, CMP and HA) functionalized by the grafting of mono or polyunsaturated fatty amine/acid (oleylamine, oleic acid and linoleic acid) via imidazole chemistry. If pullulan grafted with 2% of linoleic acid was found to be water-insoluble due to its neutral character, all other derivatives (i.e. anionic ones) with grafting rates of 3 and 10% showed good solubility in water. The physicochemical studies show a very strong associative character of these amphiphilic derivatives with the formation of physical gels in semi-diluted regime. Photocrosslinking has been demonstrated in situ thanks to rheology/UV irradiation in the presence of a Darocur 1173® photoinitiator. The preliminary results according to this photocrosslinking approach thus open interesting perspectives
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Jourdain, Antoine. "Nouvelles stratégies pour l’élaboration de polymères conducteurs ioniques fonctionnels à base 1,2,3-triazolium". Thesis, Lyon, 2020. http://www.theses.fr/2020LYSEI115.
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Cette thèse propose de nouvelles stratégies de synthèse de poly(liquides ioniques) à base 1,2,3-triazolium (TPILs) impliquant deux réactions successives et orthogonales de cycloaddition azoture-alcyne catalysée par le cuivre(I) et de N-alkylation des intermédiaires 1,2,3-triazole. Cette séquence réactionnelle permet d’élaborer des monomères liquides ioniques d’une vaste diversité de structure et de fonctions polymérisables mais également de modifier chimiquement des polymères de manière quantitative. En tirant parti des avantages de la chimie des 1,2,3-triazoliums, trois nouveaux TPILs ont été développés par des méthodes de synthèse originales. Le premier chapitre propose deux nouvelles classes de TPILs linéaires élaborés selon deux approches distinctes. La première consiste en la polymérisation AA+BB d’un monomère 1,2,3-triazolium diol synthétique avec quatre diisocyantes commerciaux pour obtenir des polyuréthanes. La seconde repose sur la modification chimique post-polymérisation d’un polysiloxane neutre fonctionnalisé thiol par greffage thiol-ène d’un liquide ionique à base 1,2,3-triazolium possédant un groupement vinylique. Ce premier exemple de TPIL à base polysiloxane possède des propriétés de conductivités ioniques remarquables. Le deuxième chapitre présente une littérature exhaustive des différentes voies de synthèses permettant d’élaborer des matériaux poly(liquides ioniques) (PILs) réticulés. Cette étude est divisée en trois parties qui distinguent les réseaux PILs obtenus par polymérisation en chaine, polymérisation par étapes et réticulation post-polymérisation. Ces matériaux sont également différenciés selon leurs microstructure (membranes denses, poreuses, gélifiées et colloïdes) et leurs applications (électrolytes solide, absorption et stockage du CO2, catalyse…). Le troisième chapitre propose une nouvelle voie d’accès à des PILs réticulés. Il traite de la synthèse d’un monomère diépoxy liquide ionique 1,2,3-triazolium puis de son homopolymérisation par ouverture de cycle cationique. Les cinétiques de polymérisation et la détermination des propriétés physicochimiques du réseau sont comparées à un analogue structural ne possédant pas de groupement liquide ionique. Cette nouvelle stratégie permet d’obtenir des matériaux de haute conductivité ionique sans l’usage de co-monomèresThis thesis proposes new strategies for synthesis of poly(ionic liquid)s based 1.2,3-triazolium (TPILs) involving two successive and orthogonal reactions of azide-alkyne cycloaddition catalyzed by copper (I) and N-alkylation of 1,2,3-triazole intermediates. This reaction sequence allows the development of ionic liquid monomers of a wide variety of structure and polymerizable functions, but also to chemically modify polymers quantitatively. Taking advantage of the chemistry benefits of 1.2,3-triazoliums, three new TPILs were developed by original synthesis methods. The first chapter proposes two new classes of linear TPILs developed using two distinct approaches. The first one consists of the AA + BB polymerization of a 1.2,3-triazolium synthetic diol monomer with four commercial diisocyants to obtain polyurethanes. The second one is the post-polymerization chemical modification of a neutral polysiloxane functionalized thiol by thiol-ene grafting of a 1.2.3-triazolium-based ionic liquid with a vinyl group. This first example of polysiloxane-based TPIL has remarkable ionic conductivity properties. The second chapter presents an exhaustive literature of the different synthesis pathways for the development of crosslinked poly(ionic liquid)s materials (PILs). This study is divided into three parts that distinguish the PILs networks obtained by chain growth polymerization, step growth polymerization and post-polymerization cross-linking. These materials are also differentiated according to their microstructure (dense, porous, gel membranes and colloid) and their applications (solid electrolytes, CO2 sorption and storage, catalysis, etc.). The third chapter proposes a new pathway to crosslinked PILs. It deals with the synthesis of an ionic liquid monomer diepoxy based 1.2,3-triazolium and then its homopolymerization by cationic ring opening polymerization. Polymerizing kinetics and physical properties of the network are compared to a structural analogue that does not have ionic liquid groups. This new strategy afforded materials with high ionic conductivity without the use of co-monomers
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Kumar, Arun. "Vanadium Complexes for DNA Crosslinking and Photodynamic Applications". Thesis, 2018. http://etd.iisc.ac.in/handle/2005/4328.
Texto completoResumen
The present thesis work deals with the studies involving synthesis of vanadium-based complexes as photoactivated chemotherapeutic as well a photodynamic therapeutic agent. Their interactions with DNA, as double-stranded DNA crosslinkers, visible light induced cytotoxic effect on cancerous cells, mechanistic aspects of cell death, and cellular localization behavior were studied.
Chapter I presents a brief introduction to the metal-based photochemotherapeutic and DNA crosslinking agents. Importance of vanadium metal in medicinal as well as biological aspects is discussed. The significance of photoactivated chemotherapy (PACT) and photodynamic therapy (PDT) in cancer treatment is discussed. A discussion on the opportunities and motivation for the development of metal-based anticancer agents is also made. DNA crosslinks and its relation to cancer and cancer treatment are presented. Objective of the present investigation is also dealt in this chapter.
Chapter II of the thesis deals with the synthesis, characterization and DNA damaging ability of a dioxovanadium(V) complex of vitamin-B6 Schiff base. The complex exhibited significant reactive oxygen species (ROS) mediated apoptotic photocytotoxicity in the cancer cells, while being essentially non-toxic in the dark. Alkaline Comet assay showed damage of nuclear DNA.
Chapter III presents synthesis and characterization of two oxovanadium(IV) complexes, viz. [VO(pyphen)Cl2] (2) and [VO(pydppz)Cl2] (3), where pyphen is 2-(2'-pyridyl)-1,10-phenanthroline and pydppz is 3-(pyridin-2-yl)dipyrido[3,2-a:2',3'-c]phenazine. The complexes exhibited photo-induced DNA crosslinking property and photo-cytotoxicity.
Chapter-IV deals with oxovanadium (IV) complexes, viz. [VO(L1/L2)Cl2]n+ (4, 5) of anthracenyl terpyridine and triphenyl phosphonium-appended anthracenyl terpyridine. Upon photo-irradiation with visible light (400-700 nm), The complexes showed significant photocytotoxicity in visible light with low dark toxicity in HeLa and MCF-7 cells. FACScan analysis showed cellular apoptosis when treated with the complex in visible light in comparison to their dark controls. The photocytotoxicity of the complexes was attributed to their DNA crosslinking ability. Fluorescence microscopic studies revealed mitochondrial localization of the complex within the cancer cells.
Chapter V deals with the synthesis, characterization, photo-induced DNA crosslinking ability and photocytotoxicity of the oxovanadium (IV) complexes, viz. [VO (dpa/L1/L2)Cl2] (7-9) of glucose or biotin appended ligands. Cell death mechanism was found out to be apoptic in nature. The complexes displayed enhanced cellular uptake in cancerous cells. The cytotoxicity of the complexes is comparable with the already available DNA crosslinking drug cis-platin.
In Chapter VI we have designed the oxovanadium (IV) complexes of BODIPY appended dipicolyl amine. The complexes, viz. [VO (bzdpa/L1/L2)Cl2] (10-12) were synthesized, characterized and their cellular uptake, photocytotoxicity, DNA crosslinking ability and mode of photo-induced cell death in cancer cells was studied. Mitochondria targeting photocytotoxic property of the complexes has been studied in details.
Finally, the summary of the dissertation and conclusions drawn from the present investigations are presented.
The references in the text have been indicated as superscript numbers and assembled at the end of each chapter. The complexes presented in this thesis are represented by bold-faced numbers. Due acknowledgements have been made wherever the work described is based on the findings of other investigators. Any omission that might have happened due to oversight or mistake is regretted.
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Bishop, Maximilienne. "Cement hydration inhibition and crosslinking in the guar-borate system". Thesis, 2001. http://hdl.handle.net/1911/17940.
Texto completoResumen
The hydration of cement and its individual mineral phases in the presence of different inhibitors has been investigated. The behavior of an exemplary oligo-phosphate, nitriltris(methylene)phosphonic acid (H6ntmp), is compared to the behavior of more traditional retarders. The reaction between H6ntmp and calcium hydroxide, tricalcium silicate, tricalcium aluminate, and cement have revealed that the calcium phosphonate complex, [Ca(H 4ntmp)]infinity, plays a role in inhibition with phosphonates. NMR and XPS data suggest that the presence of uncoordinated P-O bonds in calcium phosphonates lends phosphonates the unique ability to simultaneously complex calcium ions while adhering to hydrating aluminate surfaces, promoting heterogeneous nucleation of calcium phosphonates at the surface of aluminate minerals and blocking normal hydration reactions. Reactions with tartaric acid also forms a calcium complex on top of the aluminate phases. In contrast, sucrose, appears to act directly on the silicate phases actually accelerates the reactions of the aluminate phases.
The reactions of borate ions with diols and monosaccharides have been used to model cross-linking in the guar-borate system. Specifically, the reactions of borate with alcohols were characterized by 11B NMR to determine which reactions are most favorable. It was found that the acidity of the hydroxyl groups plays an important role in the efficiency of cross-linking, and has a greater effect on the energy of the resulting borate-diol complexes than the conformation (i.e., cis versus trans) in reactions of borate with cyclohexanediols and monosaccharides. The role of Group 1 metal salts in the borate-diol reactions was also investigated by 11B NMR and by the synthesis of model compounds. It was found that the metal cations play an important role in stabilizing the borate-diol complexes in the solid state. In solution, it was found that cross-linking is enhanced by the presence of strongly coordinating cations, as opposed to more purely ionic cations, and cross-linking is decreased in the presence of non-coordinating ammonium cations.
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Spagnola, Lisa M. "Miniemulsion copolymerization of polymerizable fatty acid-derived monomers and crosslinking of derived films via autoxidation". 2009. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3358114.
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Seto, Aaron U. "Stabilization of irradiated allografts via crosslinking and free radical scavenging". 2007. http://hdl.rutgers.edu/1782.2/rucore10001600001.ETD.16776.
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"Chemical crosslinking of ribonuclease P holoenzyme from Escherichia coli: Structure and catalytic mechanism of a ribozyme". Tulane University, 2002.
Buscar texto completoResumen
The structure of the Escherichia coli ribonuclease P (RNase P) holoenzyme was investigated by site-directed attachment of an aryl azide crosslink reagent to specific sites in the protein subunit of the enzyme. The protein subunit's interaction with a self-cleaving RNase P RNA-mini precursor-tRNA chimera (TPT118 RNA) was also investigated. The sites of crosslinking were mapped by primer extension to several conserved residues and structural features throughout the RNA. Probing the interaction between the protein subunit and TPT118 RNA allowed the confirmation of activity of crosslink sites observed with the RNase P RNA. The results of crosslinking to RNase P RNA suggest rearrangement of current tertiary models of the RNA subunit, particularly in regions poorly constrained by earlier data. Crosslinks from the protein subunit to the substrate precursor-tRNA (ptRNA) were also detected, consistent with previous crosslinking results in the Bacillus subtilis RNase P holoenzyme The interaction of the 5' end of ptRNAs with varying 5' leader lengths with the RNA subunit and holoenzyme was determined using an aryl azide crosslink reagent attached to the 5' end of the ptRNAs. The sites of crosslinking on the RNA subunit were mapped by primer extension. The sites of crosslinking to the P RNA were in agreement with previous results showing regions of the P RNA which interact with the 5' leader of ptRNA close to site of cleavage in both the B. subtilis and E. coli systems. The protein subunit blocks crosslinking sites on the P RNA in the holoenzyme when the 5' leader of ptRNAs is ≥3 bases long. These results are comparable to previous studies showing that the protein subunit interacts with the 5' leader of the substrate ptRNA and places the protein subunit next to the active site of RNase P RNA How the protein subunit affects the RNA subunit's preference in binding substrate as compared to product was analyzed using inhibition assays under single-turnover conditions. The protein subunit confers a 20-fold enhancement in the RNA subunit's binding of substrate to product. The RNA subunit alone had no preference in the binding of substrate and product. These results are in agreement with prior studies showing that the protein subunit increases the binding affinity of substrate as compared to product by the RNA subunit. Also, the importance of the universally conserved 3' CCA tail of tRNAs for binding was tested in the inhibition assays. The results confirmed previous reports that the 3' CCA is important in the RNA alone reaction, but is dispensable in the holoenzyme under single-turnover conditionsacase@tulane.edu
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Mitra, Koushambi. "Platinum(II) Complexes as Dual Action DNA Crosslinking & Photochemotherapeutic Agents". Thesis, 2016. http://etd.iisc.ac.in/handle/2005/2874.
Texto completoResumen
The thesis work delineates the rational design and successful syntheses of platinum (II) complexes for achieving light promoted dual action anticancer properties. The research work focuses on the syntheses, elaborate characterization including crystallization and mechanistic aspects of photodegradation processes. Theoretical studies were done to elucidate the properties of the excited states. The interaction of active Pt (II) species with DNA is also explored. The cellular studies include evaluation of the photo-induced cytotoxicities, mode of cell death, nature of reactive oxygen species (ROS), quantification of cellular Pt content and cellular and sub-cellular localization of the complexes.
Chapter I provides an overview of the hallmarks of cancer and the current anticancer treatment modalities. It outlines the evolution of platinum based chemotherapeutic drugs, their mechanism of action and associated disadvantages. It also depicts the resurgence of metal complexes as photosensitizers for photoactivated chemotherapy, a selective tripartite strategy which permits light induced tumor destruction. Detailed literature reports of potential transition metal complexes showing light induced generation of ROS and controlled delivery of multiple drugs in tumor microenvironment are presented. The key challenges are the delivery and controlled activation of the clinically approved platinum (II) drugs. These prime objectives of the present investigation are depicted as a concluding segment of this introductory chapter.
Chapter II includes the syntheses, characterization, evaluation of visible light induced cytotoxicity and interaction with DNA of novel ferrocenyl terpyridine appended platinum (II) complexes. Detailed mechanistic investigations revealed the important role of ferrocene in light triggered generation of reactive oxygen species. The effect of extensive conjugation on the photophysical properties of the complexes were also rationalized from theoretical calculations. The alteration in DNA binding affinities of the complexes on incorporation of a ferrocene unit in the platinum (II)terpyridines is also reflected. The work is the first report of the remarkable photocytotoxicity of platinum(II) complexes in visible light with nominal dark toxicity.
Chapter III deals with novel ferrocenyl terpyridyl platinum(II) complexes having tumor targeting biotinylated acetylides which were synthesized for achieving selective photocytotoxicity only in cancer cells. An interesting observation was the red light promoted release of biotinylated acetylide ligands from platinum centre thereby generating mono-functional Pt(II) species. The possible covalent interactions of these platinum(II) species with DNA were also explored. These biotin complexes exhibit preferential cellular uptake in BT474 breast cancer cells over HBL-100 breast normal cells resulting in targeted photocytotoxicity in visible light.
Chapter IV rationalizes design, syntheses and extensive characterization of 2-(phenylazo)pyridine based platinum(II) catecholates containing photosensitizers. The O^O donor ligand was chosen to release the more cytotoxic bi-functional platinum(II) species based on the prior knowledge of the labile Pt-O bonds. Interestingly, we observed glutathione triggered release of the catecholates imparting dual action anticancer properties to the molecules. Detailed mechanistic aspects indicated a possible reduction of the metal coordinated azo bond by cellular glutathione. The excellent photocytotoxicity in HaCaT and MCF-7 cells, cellular ROS generation and apoptosis, cellular Pt content and localization of these complexes are discussed.
Chapter V addresses the advantages of navigating the platinum(II) complexes to mitochondrial DNA instead of genomic DNA. BODIPY appended platinum(II) catecholates were synthesized and the BODIPY core was modified to fine-tune the photophysical properties. The visible light induced growth inhibitory effects of the complexes and the mechanism of cell death in light exposed cells are explored. The novelty of this work is the mitochondria targeted remarkable photocytotoxicity as well as cellular imaging properties of the complexes making them ideal candidates for developing platinum based theranostic agents.
Chapter VI presents the syntheses, characterization of unprecedented platinum(II) complexes of curcumin for dual action DNA crosslinking and photochemotherapeutic activities. The important feature of these Pt(II) prodrugs is the photorelease of curcumin from Pt(II) centre which results in controlled delivery of two potential anticancer agents. The visible light induced cytotoxicities of the complexes in HaCaT, BT474, T47D, Hep3B and HPL1D cells, their effect on the various cellular events, the interaction of the complexes with DNA and their cellular distribution in light and dark are explored.
The appropriate references are provided at the end of each chapter and allocated as superscripts in the main text. The synthesized complexes are denoted by bold-faced numbers. Crystallography data of the complexes that are structurally characterized by single crystal X-ray crystallography are given in CIF format in the enclosed CD (Appendix-I). Due acknowledgements are provided for mentioned literature reports. Any omission is purely unintentional and is deeply regretted.
INDEX WORDS: Platinum(II) complexes • Crystal structure • Visible light induced cytotoxicity • Cellular imaging • Photochemotherapeutic agents • DNA crosslink.
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Mitra, Koushambi. "Platinum(II) Complexes as Dual Action DNA Crosslinking & Photochemotherapeutic Agents". Thesis, 2016. http://etd.iisc.ernet.in/handle/2005/2874.
Texto completoResumen
The thesis work delineates the rational design and successful syntheses of platinum (II) complexes for achieving light promoted dual action anticancer properties. The research work focuses on the syntheses, elaborate characterization including crystallization and mechanistic aspects of photodegradation processes. Theoretical studies were done to elucidate the properties of the excited states. The interaction of active Pt (II) species with DNA is also explored. The cellular studies include evaluation of the photo-induced cytotoxicities, mode of cell death, nature of reactive oxygen species (ROS), quantification of cellular Pt content and cellular and sub-cellular localization of the complexes.
Chapter I provides an overview of the hallmarks of cancer and the current anticancer treatment modalities. It outlines the evolution of platinum based chemotherapeutic drugs, their mechanism of action and associated disadvantages. It also depicts the resurgence of metal complexes as photosensitizers for photoactivated chemotherapy, a selective tripartite strategy which permits light induced tumor destruction. Detailed literature reports of potential transition metal complexes showing light induced generation of ROS and controlled delivery of multiple drugs in tumor microenvironment are presented. The key challenges are the delivery and controlled activation of the clinically approved platinum (II) drugs. These prime objectives of the present investigation are depicted as a concluding segment of this introductory chapter.
Chapter II includes the syntheses, characterization, evaluation of visible light induced cytotoxicity and interaction with DNA of novel ferrocenyl terpyridine appended platinum (II) complexes. Detailed mechanistic investigations revealed the important role of ferrocene in light triggered generation of reactive oxygen species. The effect of extensive conjugation on the photophysical properties of the complexes were also rationalized from theoretical calculations. The alteration in DNA binding affinities of the complexes on incorporation of a ferrocene unit in the platinum (II)terpyridines is also reflected. The work is the first report of the remarkable photocytotoxicity of platinum(II) complexes in visible light with nominal dark toxicity.
Chapter III deals with novel ferrocenyl terpyridyl platinum(II) complexes having tumor targeting biotinylated acetylides which were synthesized for achieving selective photocytotoxicity only in cancer cells. An interesting observation was the red light promoted release of biotinylated acetylide ligands from platinum centre thereby generating mono-functional Pt(II) species. The possible covalent interactions of these platinum(II) species with DNA were also explored. These biotin complexes exhibit preferential cellular uptake in BT474 breast cancer cells over HBL-100 breast normal cells resulting in targeted photocytotoxicity in visible light.
Chapter IV rationalizes design, syntheses and extensive characterization of 2-(phenylazo)pyridine based platinum(II) catecholates containing photosensitizers. The O^O donor ligand was chosen to release the more cytotoxic bi-functional platinum(II) species based on the prior knowledge of the labile Pt-O bonds. Interestingly, we observed glutathione triggered release of the catecholates imparting dual action anticancer properties to the molecules. Detailed mechanistic aspects indicated a possible reduction of the metal coordinated azo bond by cellular glutathione. The excellent photocytotoxicity in HaCaT and MCF-7 cells, cellular ROS generation and apoptosis, cellular Pt content and localization of these complexes are discussed.
Chapter V addresses the advantages of navigating the platinum(II) complexes to mitochondrial DNA instead of genomic DNA. BODIPY appended platinum(II) catecholates were synthesized and the BODIPY core was modified to fine-tune the photophysical properties. The visible light induced growth inhibitory effects of the complexes and the mechanism of cell death in light exposed cells are explored. The novelty of this work is the mitochondria targeted remarkable photocytotoxicity as well as cellular imaging properties of the complexes making them ideal candidates for developing platinum based theranostic agents.
Chapter VI presents the syntheses, characterization of unprecedented platinum(II) complexes of curcumin for dual action DNA crosslinking and photochemotherapeutic activities. The important feature of these Pt(II) prodrugs is the photorelease of curcumin from Pt(II) centre which results in controlled delivery of two potential anticancer agents. The visible light induced cytotoxicities of the complexes in HaCaT, BT474, T47D, Hep3B and HPL1D cells, their effect on the various cellular events, the interaction of the complexes with DNA and their cellular distribution in light and dark are explored.
The appropriate references are provided at the end of each chapter and allocated as superscripts in the main text. The synthesized complexes are denoted by bold-faced numbers. Crystallography data of the complexes that are structurally characterized by single crystal X-ray crystallography are given in CIF format in the enclosed CD (Appendix-I). Due acknowledgements are provided for mentioned literature reports. Any omission is purely unintentional and is deeply regretted.
INDEX WORDS: Platinum(II) complexes • Crystal structure • Visible light induced cytotoxicity • Cellular imaging • Photochemotherapeutic agents • DNA crosslink.
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Downey, Kayla Monique. "Design and synthesis of protein chemical crosslinkers: a modular approach". Thesis, 2018. http://hdl.handle.net/2440/114024.
Texto completoResumen
The study of protein structure and interactions is pivotal in understanding the function and malfunction of complex biological systems. The structures of some proteins are unable to be determined using traditional high resolution biophysical techniques, requiring the development of amenable low resolution alternatives.
Chemical Crosslinking Mass Spectrometry (CXMS) is one technique which can be used to probe protein structure through the formation of covalent linkages between protein residues. The formation of these links is facilitated by chemical crosslinking reagents. Widespread use of the CXMS technique has been hampered primarily by analytical challenges pertaining to the detection and identification of crosslinked species using Mass Spectrometry (MS). Attempts to mitigate the challenges have been made by modifying the structure of chemical crosslinkers through the addition of functional groups such as affinity tags, isotope labels and cleavable bonds. Crosslinkers combining more than one type of functional group (combination crosslinkers) present the most promising targets for CXMS applications, combining the benefits of each functional group. However, combination crosslinkers are not commercially available, thus necessitating in-house synthesis. Incorporating more than one functionality also results in more complex molecular structures and synthetic processes, making the crosslinkers difficult to adapt to suit a particular experiment. Consequently, the use of combination crosslinkers has been limited to date to a small number of studies. The research presented in this thesis describes the development of a modular chemical crosslinker design and corresponding synthetic protocol for the synthesis of combination crosslinkers. The modular crosslinker structure can be readily modified to include a range of functional groups using a small number of different reactions, including amide coupling and O-alkylation, and commercially available starting materials such as Boc-serine, from a minimum of five synthetic steps. The utility of the synthetic process was validated through the synthesis of a crosslinker containing an alkyne functional group, which can be used to attach a biotin affinity tag through alkyne-azide Huisgen Cyclisation. Synthesis of two custom designed combination crosslinkers utilising alkyne tags and cleavable bonds is also described. The function of the cleavable bonds was established using collision induced dissociation processes within the mass spectrometer. Ensuring that a crosslinker is effective in probing quaternary structure and protein- protein interactions is essential as the investigation of these structures is a major goal of CXMS. Therefore, a crosslinking assay using Staphylococcus aureus biotin protein ligase, which forms homodimers when substrate bound, was also developed using the commercially available crosslinkers Disuccinimidyl Suberate (DSS) and Dithiobis(succinimidyl) Propionate (DSP), to enable the efficacy of crosslinkers synthesised using the modular synthetic protocol to be determined.Thesis (M.Phil.) -- University of Adelaide, School of Physical Sciences, 2018.