Gelification et degradation d'un biopolymere par voie enzymatique

This project deals with the study of chitosan using different enzymatic reactions. In the, first part of this work, we investigated gelation properties of chitosan and more specifically, enzymatic reactions potentially able to induce chitosan gelation. Indeed, chitosan-based gels have great potential for applications in tissue engineering, or as matrix in controlled delivery systems. Taking into account the data in the literature, involving a large variety of enzyme-catalysed reactions and specific chitosan physico-chemical properties, three different strategies were suggested: the first is gelation induced by phenolic derivative oxidation by tyrosinase; the second employs an enzyme to introduce chemical functions and progressively decrease polymer solubility via formation of physical interactions; finally, gelation induced by in situ pH modification resulting from an enzymatic reaction was proposed.;The second aspect of this study focused on developing a method for the in vitro evaluation of chitosan degradation by lysozyme. In this study, lysozyme was chosen because of its major responsibility in chitosan degradation in vivo. Degradation was measured as a decrease in viscosity. (Abstract shortened by UMI.).