PEGylated-folic acid–modified black phosphorus quantum dots as near-infrared agents for dual-modality imaging-guided selective cancer cell destruction

Biological systems have high transparence to 700–1100-nm near-infrared (NIR) light. Black phosphorus quantum dots (BPQDs) have high optical absorbance in this spectrum. This optical property of BPQDs integrates both diagnostic and therapeutic functions together in an all-in-one processing system in cancer theranostic approaches. In the present study, BPQDs were synthesized and functionalized by targeting moieties (PEG-NH2-FA) and were further loaded with anticancer drugs (doxorubicin) for photodynamic–photothermal–chemotherapy. The precise killing of cancer cells was achieved by linking BPQDs with folate moiety (folic acid), internalizing BPQDs inside cancer cells with folate receptors and NIR triggering, without affecting the receptor-free cells. These in vitro experiments confirm that the agent exhibited an efficient photokilling effect and a light-triggered and heat-induced drug delivery at the precise tumor sites. Furthermore, the nanoplatform has good biocompatibility and effectively obliterates tumors in nude mice, showing no noticeable damages to noncancer tissues. Importantly, this nanoplatform can inhibit tumor growth through visualized synergistic treatment and photoacoustic and photothermal imaging. The present design of versatile nanoplatforms can allow for the adjustment of nanoplatforms for good treatment efficacy and multiplexed imaging, providing an innovation for targeted tumor treatment.