Green synthesis of chitooligosaccharide-PEGDA derivatives through aza-Michael reaction for biomedical applications.

Chitooligosaccharide (COS) as an emerging material carbohydrate polymer with huge potential in biomedical applications was prepared using a microwave-assisted process. The obtained COS exhibited reduced molecular weight (Mw) and higher water solubility in comparison to chitosan while preserving the main saccharide structure and same degree of deacetylation (DD). The optimized COS (13 kDa) was then used to synthesize a new family of COS-poly(ethylene glycol) diacrylate (PEGDA) derivatives based on aza-Michael addition of acrylate groups of PEGDA to the amine groups of COS in the absence of any exterior agents. The modulation of the reaction time, temperature, pH and NH2:acrylate molar ratio, had a strong influence on the Michael reaction progress. At higher degrees of conversion of acrylate groups, COS-PEGDA derivative formed gel with high biocompatibility towards human bone mesenchymal stem cells (hBMSCs). These COS-PEGDA hydrogels synthesized at mild conditions through a green chemistry are, therefore, an innovative system combining adequate biological performance, ease of preparation, and an environmentally friendly concept of production.