Ces travaux ont pour objet l’élaboration de nouvelles structures poreuses non tissées antibactériennes. Différentes stratégies ont été développées : l’une a consisté à élaborer des mats poreux par electrospinning en utilisant un polymère biosourcé et biocompatible et l’autre voie consistait à modifier un support fibreux provenant d’un masque de protection respiratoire commercial. La méthode des assemblages par interactions ioniques en superposant de façon alternative les couches de polymères cationiques et les polymères anioniques à la surface du filtre médian en polypropylène (PP) a permis d’élaborer de nouvelles structures ayant de bonnes propriétés antioxydantes et antibactériennes. Le polymère anionique, dérivé du polymère de cyclodextrine présente l’avantage de pouvoir encapsuler un agent antimicrobien biosourcé, le carvacrol. Une autre approche a consisté à modifier des supports en PP avec de l'acide tannique, un polyphénol d'origine naturelle. Dans cette étude, deux stratégies ont été mises en place afin de fonctionnaliser le PP avec de l’acide tannique (AT). La première est l’extrusion réactive du PP avec l’AT en présence (ou non) de peroxyde de dicumyle (DCP) pour greffer directement l’acide tannique sur le PP. La deuxième stratégie consiste à polymériser l’AT au travers d’une couche poreuse de PP extraite d’un masque de protection commercial, afin de permettre l’immobilisation physique de l’AT à la surface du mat fibreux en PP. Le greffage en surface via un procédé “grafting from” a également été étudié. Ces matériaux ont montré de bonnes propriétés antiradicalaires. / The purpose of this work is to develop new antibacterial non-woven porous structures. Different strategies were developed: one was to develop porous structures by electrospinning using a biosourced and biocompatible polymer, the other was to modify a fibrous support from a commercial respiratory protection mask. Assembling materials using ionic interactions by alternatively superposing cationic polymer layers and anionic polymers on the surface of the polypropylene (PP) median filter allowed to develop new structures with good antioxidant and antibacterial properties. The anionic polymer, derived from the cyclodextrin polymer, has the advantage of being able to encapsulate a bio-based antimicrobial agent, carvacrol. Another approach was to modify PP filters with tannic acid, a naturally occurring polyphenol. In this study, two strategies were implemented to functionalize PP with tannic acid (TA). The first is the reactive extrusion of PP with TA in the presence (or not) of dicumyl peroxide (DCP) to directly graft tannic acid onto PP. The second strategy consists in polymerizing the TA through a porous layer of PP extracted from a commercial mask, in order to allow the physical immobilization of the TA on the surface of the PP fibrous mat. Surface grafting using a "grafting from" process was also studied. These materials have shown good anti-free radical properties.

Vascular networks are required to support the formation and function of three-dimensional tissues. Biodegradable scaffolds are being considered in order to promote vascularization where natural regeneration of lost or destroyed vascular networks fails. Particularly; composite materials are expected to fulfill the complex demands of a patient's body to support wound healing. Microbial biopolyesters are being regarded as such second and third generation biomaterials. Methylobacterium extorquens is one of several microorganisms that should be considered for the production of advanced polyhydroxyalkanoates (PHAs). M. extorquens displays a distinct advantage in that it is able to utilize methanol as an inexpensive substrate for growth and biopolyester production. The design of functionalized PHAs, which would be made of both saturated short-chain-length (scl, C [less than or equal to] 5) and unsaturated medium-chain-length (mcl, 6 [less than or equal to] C [less than or equal to] 14) monomeric units, aimed at combining desirable material properties of inert scl/mcl-PHAs with those of functionalized mcl-PHAs. By independently inserting the phaC1 or the phaC2 gene from Pseudomonas fluorescens GK13, recombinant M. extorquens strains were obtained which were capable of producing PHAs containing C-C double bonds. A fermentation process was developed to obtain gram quantities of biopolyesters employing the recombinant M. extorquens ATCC 55366 strain which harbored the phaC2 gene of P. fluorescens GK13, the better one of the two strains at incorporating unsaturated monomeric units. The PHAs produced were found in a blend of scl-PHAs and functionalized scl/mcl-PHAs (4 [less than or equal to] C [less than or equal to] 6), which were the products of the native and of the recombinant PHA synthase, respectively. Thermo-mechanical analysis confirmed that the functionalized scl/mcl-PHAs exhibited the desirable material properties expected. This project contributed to current research on polyhydroxyalkanoates at different levels. The terminal double bonds of the functionalized scl/mcl-PHAs are amenable to chemical modifications and could be transformed into reactive functional groups for covalently linking other biomacromolecules. It is anticipated that these biopolyesters will be utilized as tissue engineering materials in the future, due to their functionality and thermo-mechanical properties.

We now report an in depth analysis of the successful in vitro enzymatic synthesis of PHB utilizing the three-enzyme system from the bacteria Cupriavidus necator. Using HPLC methodology developed in this laboratory, and by adding each enzyme in a step-wise manner, we follow each individual stage in the three-enzyme route for PHB synthesis and delineate all stoichiometric relationships. We report the construction of the first metabolic model developed specifically for analyzing in vitro enzymatic PHB synthesis. We developed a hands-on student laboratory for culturing, producing, isolating, and purifying the bacterial biopolyesters PHB. We now report the first structural characterizations of iso-CoA, acetyl-iso-CoA, acetoacetyl-iso-CoA, and beta-hydroxybutyryl-iso-CoA using MS, MS/MS, and homo- and hetero-nuclear NMR analyses.We describe HPLC methodology to separate the isomers of several iso-CoA-containing compounds and report the first examples of iso-CoA-containing compounds acting as substrates in enzymatic acyl-transfer reactions. We describe a simple regioselective synthesis of iso-CoA from CoA. We also demonstrate a plausible mechanism, which accounts for the existence of iso-CoA isomers in commercial preparations of CoA-containing compounds. Herein we report that phenylaminoethyl selenide compounds protect DNA from peroxynitrite-mediated single-strand breaks. The mechanism of protection against peroxynitrite mediated DNA damage was investigated by HPLC. The chemistry of the reaction between peroxynitrite and HOMePAES was investigated using HPLC and HPLC/MS. The unique chemistry of the reaction between peroxynitrite and HOMePAES was investigated using HPLC and HPLC/MS. We report the development of novel CDB derivatives, which are selective COX-II inhibitors. A series of compounds were assayed with an in vitro colorimetric inhibitor screening and with a whole blood ELISA screening and the results indicate that MST is a selective inhibitor of COX-II.