Black Phosphorus Nanosheet with High Thermal Conversion Efficiency for Photodynamic/Photothermal/Immunotherapy.

The synergistic treatment through multiple treatment methods can effectively improve the effect of tumor treatment. Phototherapy and immunotherapy are two innovative and promising cancer diagnosis and treatment methods, so they are good candidates for collaborative diagnosis and treatment. Here we report a new inorganic nanosystem, which uses ultrathin black phosphorus (BP) nanosheets (minimum: 13 nm) as carriers and equips with up-conversion luminescence (UCL) nanoparticles as imaging probes, so that the system can generate photothermal and photodynamic effects to treat tumors together with immunotherapy. Especially, the photothermal conversion efficiency can reach 30.84% under the 980 nm laser, which is significantly higher than the conventional Au nanoparticles including nanostars (22.63%) and Au nanorods (23.33%). When the system works in conjunction with immunotherapy, it not only shows a good ability to treat tumors but also can inhibit tumors for a long time and prevent recurrence. Different from the past, in this work, we not only use this strategy to evaluate the performance during the treatment cycle but also observe the mice after the treatment to verify the long-term effect of suppressing tumors. Overall, this study reveals a new inorganic nanosystem and proposes a new strategy for treating tumors in combination with immunotherapy. The present work illustrates the new opportunities for the treatment of primary tumors.