Biodegradable scaffolds of chitosan and PEGylated polyesters

In recent years, research on biomaterials has been directed towards the development and optimization of new scaffolds for tissue regeneration; among the various biomaterials, chitosan has been the subject of numerous studies for potential applications. Chitosan has been used in various applications of bone tissue engineering since it was shown that it is able to promote the growth and deposition of mineral matrix of osteoblasts in culture. Furthermore, chitosan is biocompatible, biodegradable and can be molded into porous structures to promote osteoconduction, thanks also to its ability to bind growth factors and release them in a controlled manner. Unfortunately, the chitosan alone shows quite low mechanical strength and too fast degradability. Therefore a solution can be represented by the use of a composite material. The aim of this work is to conjugate the properties of chitosan with those of PEGylated biodegradable polyester like poly(L)-lactide and poly(L-lactide-co-glycolide) to perform scaffold for tissue engineering application. We studied the influence of the synthesized copolymers, obtained by Ring Opening Polymerization, on the structural properties (e.g. porosity, swelling and mechanical behaviour) of the polysaccharide scaffolds. Chitosan was mixed with either mPEG-g-P(L)LA and mPEG-g-P(L)LGA at a ratio of 1:2 and freeze dried cylindrical samples were prepared, and subsequently thermally cross-linked to produce the composite scaffolds. The prepared scaffolds were observed using a Scanning Electron Microscope (SEM), weighted in dried and wet condition and tested in compression in order to assess their morphology, swelling properties and mechanical strength. The formation of cross-linked composite of chitosan with either mPEG-g-P(L)LA and mPEG-g-P(L)LGA resulted in scaffold with suitable porous structures and improved mechanical properties. These preliminary results are a fundamental step before the biological characterization with cells.