Glutathione degradable manganese-doped polydopamine nanoparticles for photothermal therapy and cGAS-STING activated immunotherapy of lung tumor.

Photothermal therapy (PTT), which utilizes nanomaterials to harvest laser energy and convert it into heat to ablate tumor cells, has been rapidly developed for lung tumor treatment, but most of the PTT-related nanomaterials are not degradable, and the immune response associated with PTT is unclear, which leads to unsatisfactory results of the actual PTT. Herein, we rationally designed and prepared a manganese ion-doped polydopamine nanomaterial (MnPDA) for immune-activated PTT with high efficiency. Firstly, MnPDA exhibited 57.2% photothermal conversion efficiency to accomplish high-efficiency PTT, and secondly, MnPDA can be stimulated by glutathione (GSH) to the release of Mn2+, and it can produce ·OH in a Fenton-like reaction with the overexpressed H2O2 and stimulate the cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) pathway. These two synergistically can effectively remove lung tumor cells that have not been ablated by PTT, resulting in an 86.7% tumor suppression rate under laser irradiation of MnPDA in vivo, and further significantly activated the downstream immune response, as evidenced by an increased ratio of cytotoxic T cells to immunosuppressive Treg cells. Conclusively, the GSH degradable MnPDA nanoparticles can be used for photothermal therapy and cGAS-STING-activated immunotherapy of lung tumors, which provides a new idea and strategy for the future treatment of lung tumors.