Stable and Multifunctional Dye-Modified Black Phosphorus Nanosheets for Near-Infrared Imaging-Guided Photothermal Therapy

Nanomedicines intergrating both therapy and diagnosis functions provide a promising strategy for anticancer treatment. As novel two-dimensional materials, black phosphorus nanosheets (BPs) possess unique properties for biomedical applications, pratically for photothermal therapy (PTT) of cancer, but their lack of air and water stability may hinder their application. Herein, a covalent functionalization strategy based on Nile Blue (NB) dye via diazonium chemistry is established to modify BPs, not only enhancing the stability of BPs but also rendering BPs via near-infrared (NIR) fluorescence, forming a novel multifunctional nanomedicine with both PTT and NIR imaging capabilities. In vitro tests demonstrate that the dye-modified BPs (named NB@BPs) have good biocompatibility and exhibit strong PTT and NIR imaging efficiency. In vivo experiments show that the NB@BPs can mark the tumor site with red fluorescence and lead to efficient tumor ablation under NIR irradiation. These results reveal a potential BP-based nanomedicine with multiple functionalities that bode well for anticancer applications.