PH-responsive UV crosslinkable chitosan hydrogel via “thiol-ene” click chemistry for active modulating opposite drug release behaviors

Abstract

Numbers of UV crosslinkable chitosan hydrogels through chemical modification had drawn increasing attention, however most of these chitosan hydrogels lost the pH-responsive performance because plenty of amino groups (‒NH2) in chitosan were consumed by reacting with other functional groups. To construct a pH-responsive UV-crosslinkable chitosan hydrogel for active modulating drug release with desired behavior, C6-OH selectively modified chitosan via protection/deprotection strategy to amino groups was synthesized, the allyl groups on C6 site and amino groups on C2 site endowed chitosan with UV crosslinking capability and pH responsiveness, respectively. Rapid UV crosslinking gelation (30 s) with low-dose UV irradiation (4 mW/cm2) via “thiol-ene” click chemistry were demonstrated for the patterned microgel and in-situ formed hydrogel in vivo. The swelling and shrinkage of hydrogel could active modulate the opposite release behaviors of doxorubicin (DOX) and bovine serum albumin (BSA) in different pH medium. The smart UV-crosslinkable chitosan hydrogel via click chemistry might provide a new drug carrier for active modulating opposite drug release behaviors.