Novel chitosan derivative soluble at neutral pH and in-situ gellable via peroxidase-catalyzed enzymatic reaction

Abstract

Chitosan with phenolic hydroxyl groups (Chit-Ph) was synthesized by conjugating chitosan with 3-(p-hydroxyphenyl)propionic acid using aqueous-phase carbodiimide activation chemistry. By this conjugation, we could obtain chitosan derivatives soluble at neutral pH and gellable via a peroxidase-catalyzed reaction within seconds: The Chit-Ph with higher content of Ph groups showed higher solubility at neutral pH. The neutral Chit-Ph solutions gelated via an enzymatic reaction by consuming H2O2. The time necessary for gelation decreased with increasing content of Ph groups, temperature, peroxidase concentration, and decreasing H2O2 concentration. The content of Ph groups also influenced the mechanical property of the resultant gels. In addition, L929 cells, which were contacted to the enzymatically crosslinked Chit-Ph gels for 20 h, showed 96.5% viability, and were observed to grow next to the gels. These results demonstrate that Chit-Ph has the potency for use as injectable hydrogels in applications such as tissue engineering and drug delivery.