Organic Near-Infrared-II Nanophotosensitizer for Safe Cancer Phototheranostics and Improving Immune Microenvironment against Metastatic Tumor.

Current tumor immunotherapy has excellent application prospects compared with traditional radiotherapy and chemotherapy, but there are still limitations, such as considerable side effects. This problem can be partially solved by treating the local tumor to induce antitumor immunity. In our study, a novel organic photosensitizer Y8 was used to synthesize nanoparticles (Y8 NPs) via a simple nanoprecipitation method. Further investigation indicated the practical photodynamic and photothermal effects of Y8 NPs with 808 nm laser irradiation. Because of its long-wavelength absorption, Y8 NPs also have excellent imaging effects near-infrared-II region. In metastatic tumor-bearing murine models, Y8 NPs can effectively induce phototherapy, suppressing the growth of both primary and metastatic tumors without apparent systemic toxicity through local photodynamic and photothermal therapy synergistic enhancement of antitumor immunity. This study offers a promising therapeutic strategy for synergetic phototherapy and immunotherapy in tumor treatment.