Polyamides are versatile polymers and includes naturally occurring macromolecules such as proteins as well as purely synthetic materials such as Nylon-3 and Nylon-6 polymers. While there are different ways to prepare polyamides, polyamide synthesis using anionic ring opening polymerization of lactams is the most widely used technique, due to the ease in preparation, excellent control in molecular weight and availability of wide variety of monomers. Our group reported the preparation of carbohydrate-based polyamides called poly-amido-saccharides (PASs) using anionic ring opening polymerization of sugar b-lactam monomers. The PASs reported so far includes glucose, galactose, altrose and maltose PASs, and functional PASs with n-octyl, carboxylate and amine functionalities. Sulfated or block poly-amido-saccharides on the other hand are unknown. In this thesis, I describe the synthesis of sulfated and block poly-amidosaccharides as well as evaluation of their biomedical applications. Naturally occurring sulfated polysaccharides play important roles in anticoagulation, lubrication of cartilage, and in developmental processes. New glucose-based non-regioselectively and regioselectively sulfated poly-amido-saccharides are prepared by the polymerization of protected glucose b-lactams, followed by post-polymerization modification reactions. All polymers are water soluble, non-cytotoxic, and adopt helical conformations. I evaluated the anticoagulant activity of the sulfated polymers using in vitro, ex vivo, and in vivo methods as well as determined the mechanism of anticoagulation by amidolytic activity inhibition assays. Additionally, I synthesized new block copolymers as block copolymers are used for various applications including latex paints and pressure sensitive adhesives. Specifically, carbohydrate-based amphiphilic polymers are of interest for drug delivery applications, due to favorable properties such as cytocompatibility, low immunogenicity, and longer circulation time. We prepared PAS-based amphiphilic block polymers with varied polymer length, hydrophobic to hydrophilic ratio, and stereochemistry of hydrophilic component. I characterized these amphiphilic polymers by NMR, IR, GPC, DSC, TGA and CD, and they self-assemble in water to form nanostructures as determined by DLS, SEM, and cryo-TEM, and are non-cytotoxic. / 2024-11-16T00:00:00Z

Yes / The polysialyltransferases are biologically important glycosyltransferase enzymes responsible for the biosynthesis of polysialic acid, a carbohydrate polymer that plays a critical role in the progression of several diseases, notably cancer. Having improved the chemical synthesis and purification of the fluorescently-labelled DMB-DP3 acceptor, we report optimisation and validation of a highly sensitive cell-free high-throughput HPLC-based assay for assessment of human polysialyltransferase activity.

Gastrointestinal microflora has been shown to have a bi-directional relationship with the host immune system. A variety of fermentable carbohydrate polymers largely pass through the small intestine, providing fermentable substrates for gut microflora. Dietary fibre supplementation may provide a strategy for manipulating the intestinal bacterial profile, changing the interaction with the mucosal immune system, thereby modulating the host immune system. We used a BBc rat animal model to evaluate the effects of oat bran and wheat bran dietary fibre on the immune system. Previous collaborative efforts have shown that these dietary fibres can change the intestinal microflora, with wheat bran fibre showing a greater ability to influence colonic microbial community diversity. We have shown that dietary wheat bran fibre led to reduced IL-4 levels in the liver and T lymphocyte numbers in the Mesenteric Lymph Node and may be involved in reduced IgA levels in the cecal contents. In addition, IgA in the cecal contents was decreased while MLN B cell numbers increased in response to dietary wheat bran fibre. It was observed that neither wheat bran or oat bran treatments exerted any pro-inflammatory effects, with oat bran actually improving antioxidant status. These results suggest that both oat and wheat bran fibre treatments induce changes in the intestinal microflora, and that the microflora changes due to wheat fibre are associated with immunomodulatory effects on the host. This type of dietary fibre supplementation could ultimately provide a potential strategy for promoting health through microflora-associated effects on the immune system.