Poly-l-lysine derivative-coated black phosphorus as a nanoplatform for photothermal chemotherapy to enhance anti-tumor efficiency.

Severe systemic toxicity and side effects are major obstacles to the success of chemotherapy for tumors. Regardless of the choice of chemotherapy drugs, the safety of drug delivery materials is crucial, and therefore, there have been various efforts to improve the therapeutic effect and the biological safety of drug delivery systems (DDSs). In this study, a dual stimulus-response DDS (PLL-SS@DOX-BP) was constructed based on the biomaterials of black phosphorus (BP) nanosheets and poly-l-lysine (PLL) to enhance the treatment of doxorubicin hydrochloride (DOX) for breast cancer. The PLL derivative was nano-coated on the surface of drug-loaded BP nanosheets, and it prevented premature leakage of the drug and maintained the stability of the DDS. The introduced disulfide bonds and photothermal agent BP enabled the redox and near-infrared responsive drug release of the DDS, and the coated PLL derivative on the nanocarrier decreased premature leakage of the drug before the DDS reached the tumor tissues. The in vitro and in vivo experiments showed that the combination of biomaterial (PLL) and photothermal material (BP nanosheets) exhibited excellent biological safety and remarkable drug delivery capacity. Moreover, the pharmacodynamic studies indicated that PLL-SS@DOX-BP is a powerful vehicle for photothermal therapy in combination with chemotherapy. Compared with chemotherapy alone, the developed DDS displayed enhanced anti-tumor efficiency with decreased systemic toxicity, and thus, it has the potential to be a promising anti-tumor treatment strategy.