Black Phosphorus Nanosheets Immobilizing Ce6 for Imaging-Guided Photothermal/Photodynamic Cancer Therapy

Abstract

In preclinical and clinical research, to destroy cancers, particularly those located in deep tissues, is still a great challenge. Photodynamic therapy and photothermal therapy are promising alternative approaches for tissue cancer curing. Black phosphorus (BP)-based nanomaterials, with broad UV-vis near-infrared absorbance and excellent photothermal effect, have shown great potential in biomedical applications. Herein, a biocompatible therapeutic platform, chlorin e6 (Ce6)-decorated BP nanosheets (NSs), has been developed for fluorescence and thermal imaging-guided photothermal and photodynamic synergistic cancer treatment. Taking advantage of the relatively high surface area of exfoliated BP NSs, the PEG-NH-modified BP NSs (BP@PEG) are loaded with a Ce6 photosensitizer. The resulted BP@PEG/Ce6 NSs not only have good biocompatibility, physiological stability, and tumor-targeting property but also exhibit enhanced photothermal conversion efficiency (43.6%) compared with BP@PEG NSs (28.7%). In addition, BP@PEG/Ce6 NSs could efficiently generate reactive oxygen species because of the release of the Ce6 photosensitizer, which is also verified by in vitro studies. In vivo fluorescence imaging suggests that BP@PEG/Ce6 NSs can accumulate in the tumor targetedly through the enhanced permeability and retention effect. Both in vitro and in vivo studies suggest that BP@PEG/Ce6 can be a promising nanotheranostic agent for synergetic photothermal/photodynamic cancer therapy.

2D Black Phosphorus–Based Biomedical Applications

“…Recently, Yang et al fabricated chlorin e6 (Ce6)‐modified BP nanosheets (BP@PEG/Ce6) by loading Ce6 photosensitizer onto PEG‐NH2‐modified BP NSs (BP@PEG) for imaging‐guided photothermal/photodynamic cancer therapy. Both in vitro and in vivo experiments have shown that BP@PEG/Ce6 has a promising application prospect for the synergistic effect of photosynthetic/photodynamic against cancer.…”

Recent Advances on Black Phosphorus for Biomedicine and Biosensing

“…Polymer encapsulation has been commonly applied to improve the stability of nano‐BP in biological environment. PEG is the most popular one, and its encapsulation on the surface of nano‐BP appropriately prevents the direct contact with water, further enhancing the physiological stability and biocompatibility of nano‐BP . PEGylated BP nanoparticles can be synthesized directly by one‐pot solventless high‐energy mechanical milling technique.…”

“…PTT utilizes photoabsorbing agents to perform hyperthermia‐induced cell death while PDT adopts the photosensitizers to generate cytotoxic reactive oxygen species (ROS) . Nano‐BP has been at the center of tremendous research on their application to PTT as well as PDT owing to their unique optoelectronic properties …”

Tip‐enhanced spectroscopy of 2D black phosphorus

“…Due to its excellent optical and electronic properties, two‐dimensional (2D) nanomaterials have great potentiality in plasmon‐enhanced spectroscopy, optoelectronic and thermoelectric device, and energy and biomedicine fields . The rapidly developed 2D black phosphorus (BP) attracts extensive attention because of its tunable bandgap that fills the gap between graphene with zero bandgap and transitional metal dichalcogenides with larger bandgap .…”