Characterization of ring-opening polymerization of genipin and pH-dependent cross-linking reactions between chitosan and genipin

A chitosan-based polymeric network was synthesized by crosslinking with a naturally occurring crosslinking agent, genipin. The result showed that the crosslinking reactions were pH-dependent. Under basic conditions, genipin underwent a ring-opening polymerization prior to crosslinking with chitosan. This ring-opening polymerization of geninpin was initiated by extracting proton from the hydroxyl groups at C-1 deoxylaganin aglycone, followed by opening the dihydropyran ring to conduct an aldol condensation. The results indicated a direct relationship between the mode of crosslinking reaction, and the swelling and enzymatic hydrolysis properties of the genipin-crosslinking chitosan gels.