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.