Plug-and-play prussian blue-manganese hydrogel for tumor photoimmunotherapy in vivo

Photothermal-immunotherapy is a highly promising approach for tumor combination treatment, but developing photoimmunotherapy agents with the potential for clinical translation continues to present a considerable challenge. Herein, we developed a plug-and play prussian blue-Mn gel (PBM gel) for in vivo tumor photoimmunotherapy. The PBM gel was rapidly synthesized within minutes by simply mixing Fe³⁺, Fe(CN)₆^4-, sodium alginate (ALG) solution, and Mn²⁺, without the need for further purification (100 % yield), making it ready for immediate use. The PBM gel offers several key advantages, including a simple composition, an easy-to-follow synthesis process, cost-effectiveness, and large-scale production ability (over 1000 g in a single batch). Furthermore, PBM gel exhibited outstanding near-infrared II photothermal heating capability (23 % of photothermal conversion efficiency), immune activation effects, and Fenton-like catalytic activity. In a mice tumor model, the PBM gel effectively suppressed tumor growth by combining photothermal and immunotherapy at a lower power density without obvious side effects. Given that all components of the PBM gel are FDA-approved drugs or biomaterials, and considering its plug-and-play nature, the proposed PBM gel offers a novel clinically translatable strategy for the development of powerful tumor combination treatments.