Near-infrared light-triggered degradable hyaluronic acid hydrogel for on-demand drug release and combined chemo-photodynamic therapy.

In this study, an injectable and near-infrared (NIR) light-triggered ROS-degradable hyaluronic acid hydrogel platform was developed as localized delivery vehicle for photosensitizer protophorphyrin IX (PpIX) and anticancer drug doxorubicin (DOX), to achieve superior combined chemo-photodynamic therapy with light-tunable on-demand drug release. The in situ-forming hydrogel fabricated readily via the formation of dynamic covalent acylhydrazone bonds could efficiently prevent severe self-quenching effect of water-insoluble PpIX due to the covalent binding, leading to localized enhanced photodynamic therapy (PDT). Moreover, the extensive ROS generated by the hydrogel under NIR light irradiation could not only realize efficient PDT effect, but also cleave the ROS-cleavable small molecule crosslinker, inducing the desirable degradation of hydrogel and subsequent on-demand DOX release for cascaded chemotherapy. The developed versatile hyaluronic acid hydrogels have tunable properties, excellent biocompatibility, biodegradability and exhibit outstanding therapeutic effects in both in vitro cellular experiments and in vivo antitumor studies.