Violet Phosphorus Nanosheet: A Biocompatible and Stable Platform for Stimuli-Responsive Multimodal Cancer Phototherapy

As a functional 2D material, black phosphorus (BP) has garnered wide attention from many researchers in recent years. BP has a wide NIR absorption window and is a promising candidate for cancer phototherapy including photothermal therapy (PTT) and photodynamic therapy (PDT). However, due to its rapid degradation and short shelf-life in conventional water, the application of BP in the field of cancer therapy is limited. Violet phosphorus (VP), the more stable allotrope of phosphorus, has not yet been investigated for its function and biological application. In this study, VP nanosheets are successfully fabricated by liquid-phase exfoliation and demonstrated that their shelf-life in deionized water could be as long as 10 days, which is much longer than that of BP. Through in vivo and in vitro experiments, the PDT, PTT, and catalytic therapeutic effects of VP, as well as its excellent biosafety for the first time are shown. VP effectively inhibits tumor growth without causing major side effects. The current study provides new ideas and strategies for the biological application of 2D sheets of phosphorus isotope and lays the foundation for further studies on exploring the biomedical application of phosphorus isotopes.