Chemical modification and processing of polysaccharides as a versatile platform of biomaterials from renewable resources

The last decade has witnessed an upsurge of interest toward the use of natural polymers in biomedical applications in virtue of their inherent biocompatibility, biodegradability and the need to find safer alternative to materials of synthetic origin. Among them, polysaccharides revealed as the most promising candidates due to their unique abundance and chemical versatility. Recently a growing interest has been addressed toward the individuation of cheaper and more sustainable resources of polysaccharides whose exploitation could not interfere with food chain production or cause environmental issues. The aim of the present PhD research project was the exploitation of polysaccharides from sustainable resources in the development of materials suitable for biomedical applications. Accordingly, ulvan and dextran were selected as most promising polysaccharide materials since they could be both obtained from waste natural resources, such as algal biomass and microbial fermentation respectively. In particular the research was focused on the exploitation of algal biomass for the extraction of sulphated polysaccharides with a focus on Ulvan; chemical approaches for the conversion of Ulvan in suitable matrices for injectable systems in tissue engineering and/or drug delivery; exploitation of polysaccharides obtainable from microbial fermentation processes, such as dextran, in the development of novel materials for analytical applications. Ulvan was successfully modified either with thermosensitive units or enzymatic substrates in order to obtain rapid gelation of its solutions at physiological conditions by means of external stimuli. The developed materials were submitted to chemical-physical and biological characterization, which confirmed their feasibility for being used as injectable systems in biomedical applications. Dextran was successfully used for the development of hybrid resin, comprising crosslinked polystyrene as rigid core and the polysaccharide as a covalently bound shell, suitable as a novel stationary phase for the separation and purification of immunoglobulins. The resin was found to represent an innovative platform of materials having the proper combination of mechanical and chemical properties needed for being successfully applied in the separation of proteins. The operative steps adopted for the preparation of the polysaccharide-based devices were designed to address a sustainability of the envisaged processes by minimizing the use of reagents and experimental conditions harmful for the environment. Overall the materials developed during the present PhD research activity represented a worthy effort to converting waste natural resources into innovative matrices for for high-value added applications