Intracellular Mechanistic Understanding of 2D MoS₂ Nanosheets for Anti-Exocytosis-Enhanced Synergistic Cancer Therapy

Emerging two-dimensional (2D) nanomaterials, such as transition-metal dichalcogenide (TMD) nanosheets (NSs), have shown tremendous potential for use in a wide variety of fields including cancer nanomedicine. The interaction of nanomaterials with biosystems is of critical importance for their safe and efficient application. However, a cellular-level understanding of the nano-bio interactions of these emerging 2D nanomaterials (i.e., intracellular mechanisms) remains elusive. Here we chose molybdenum disulfide (MoS₂) NSs as representative 2D nanomaterials to gain a better understanding of their intracellular mechanisms of action in cancer cells, which play a significant role in both their fate and efficacy. MoS₂ NSs were found to be internalized through three pathways: clathrin → early endosomes → lysosomes, caveolae → early endosomes → lysosomes, and macropinocytosis → late endosomes → lysosomes. We also observed autophagy-mediated accumulation in the lysosomes and exocytosis-induced efflux of MoS₂ NSs. Based on these findings, we developed a strategy to achieve effective and synergistic in vivo cancer therapy with MoS₂ NSs loaded with low doses of drug through inhibiting exocytosis pathway-induced loss. To the best of our knowledge, this is the first systematic experimental report on the nano-bio interaction of 2D nanomaterials in cells and their application for anti-exocytosis-enhanced synergistic cancer therapy.