Multifunctional mesoporous black phosphorus-based nanosheet for enhanced tumor-targeted combined therapy with biodegradation-mediated metastasis inhibition.

Functionalizing black phosphorus nanosheet (BP) with efficient drug loading and endowing mesoporous silica nanomaterials with appropriate biodegradation for controllable tumor-targeted chemo-photothermal therapy are still urgent challenges. Herein, an ordered mesoporous silica-sandwiched black phosphorus nanosheet (BP@MS) with the vertical pore coating was prepared. The strategy could not only enhance the BP's dispersity and improve its doxorubicin (DOX)-loading efficiency, but also facilitate post-modification such as PEGylation and conjugation of targeting ligand, TKD peptide, yielding BSPT. A DOX-loaded BSPT-based system (BSPTD) showed heat-stimulative, pH-responsive, and sustained release manners. In vitro and in vivo results demonstrated that BSPTD had a delayed but finally complete degradation in physiological medium, contributing to an optimal therapeutic window and good biosafety. As a result, BSPTD can achieve an effective chemo-photothermal synergistic targeted therapy of tumor. Moreover, treating by BSPTD was found to be capable of remarkably inhibiting the lung metastasis of tumor, attributing to the photothermal degradation-facilitated secondary drug delivery. Our study provided a robust strategy to functionalize BP nanosheet and biodegrade the mesoporous silica for extended biomedical applications.