Persistent Luminescence Immune Hydrogel for Photodynamic-Immunotherapy of Tumors In Vivo

Persistent luminescence material (PLM)-based photodynamic therapy (PDT) has shown tremendous promise in tumor elimination via avoiding continuous external light illumination. In addition, the tumor-associated antigens produced by PDT can trigger systemic antitumor immune responses, but only exhibit a limited immunotherapy effect. Herein, a persistent luminescence immune hydrogel is developed via a "turning solid into gel" strategy by introducing a PLM and an immunoadjuvant (R837) into an alginate-Ca2+ hydrogel for rechargeable photodynamic-immunotherapy of tumors, for the first time. The designed PLM-R837-ALG hydrogel exhibits the intact persistent luminescence of the PLM, 100% of utilization efficiency of the hydrophobic precursors, good biocompatibility and syringeability, and can be easily injected into tumors to serve as an internal light source for efficiently activating photosensitizers to induce a sustained PDT effect. Moreover, the loaded R837 can significantly amplify the immunogenicity of tumor-associated antigens originating from PL sensitized PDT, thereby leading to a powerful immune response to suppress tumors in vivo. The proposed PL-based photodynamic-immunotherapy provides a novel combined tumor treatment paradigm.