Preparation and properties of photo/oxidative dual-crosslinked hydrogels based on modified chitosan and PEGDA

Chitosan hydrogels have presented great potential in tissue engineering applications due to their biocompatibility and the capacity to kill bacteria. However, poor mechanical and rapid degradation properties remain the major obstacles to their further utilization. In this work, catechol-modified methacryloyl chitosan (CMC) was prepared by first grafting methacrylic anhydride (MA) as a photosensitizer onto a chitosan to form methacryloyl chitosan (MC), and then introducing the catechol group on the MC backbone. Then, a single-crosslinked hydrogel (CMC/PEGDA hydrogel) and a dual-crosslinked hydrogel (O-CMC/PEGDA hydrogel) were designed by combining CMC with poly(ethylene glycol) diacrylate (PEGDA) via photo-crosslinking and oxidative-crosslinking. The formation mechanism and properties of the two hydrogels were investigated by XPS, SEM, swelling, in vitro degradation and mechanical testing. It is found that hydrophily, microstructure, mechanical properties, equilibrium swelling percentage and degradation rate can be regulated by changing the molecular weight of PEGDA and substitution of CMC. In addition, because of dual-crosslinked architecture, O-CMC/PEGDA hydrogels were endowed with a more robust mechanical property, more compact pore structure, lower degradation ratio and better anti-swelling ability in comparison with those of CMC/PEGDA hydrogels. In general, these hydrogels were easy to prepare and showed desirable comprehensive performance, revealing the great potential for application in tissue engineering field.