Photodynamic therapy: When van der Waals heterojunction meets tumor

Clinically approved photodynamic therapy (PDT) has emerged as an alternative treatment for cancers and malignant diseases; however, high quality PDT agents were still in great demand. Herein, the van der Waals (vdW) heterostructure of graphitic carbon nitride (g-C3N4, abbreviated as CN here) and metallic molybdenum disulfide (1T-MoS2, abbreviated as MS here) was fabricated, PEGylated, and then investigated. By making use of the extraordinary antenna effect and the ultrafast electron transfer rate of metallic molybdenum disulfide, as well as the efficient separation of photogenerated electron-hole pairs of the final heterojunction, massive reactive oxygen species (ROS) can be generated under 670 nm laser irradiation together with the as-synthesized g-C3N4@1T-MoS2 vdW nanostructure (CNMS), which should be largely owed to the appealing photocatalytic water splitting property of the CNMS structure. It was well proved by the in vitro studies that the intracellularly produced ROS can result in cell death, by the way of inducing cell apoptosis and/or necrosis through mediating phosphatidylserine ectropion, mitochondrial depolarization, and chromosomal DNA fragmentation, as well as up-regulating the expression of apoptosis-related proteins and unbalancing intracellular redox homeostasis. In vivo exploration also gave out satisfactory results that the tumor growth could be significantly inhibited by the photodynamic therapy. Additionally, outstanding biocompatibility and biosafety were also guaranteed. All these results provided compelling evidences for that the CNMS vdW heterostructure is an aussichtsreich nano-photosensitizer, and may provide some fresh ideas for the developing of nanomedicine for PDT application.