Enzymatic Biodegradability of Pristine and Functionalized Transition Metal Dichalcogenide MoS2 Nanosheets

2D transition metal dichalcogenide MoS2 nanosheets are increasingly attracting interests due to their promising applications in materials science and biomedicine. However, their biocompatibility and their biodegradability have not been thoroughly studied yet. Here, the biodegradability of exfoliated pristine and covalently functionalized MoS2 (f-MoS2) is investigated. First, biodegradability of these nanomaterials is evaluated using plant horseradish peroxidase and human myeloperoxidase. The results reveal that the enzymatic degradability rate of MoS2 and f-MoS2 is slower than in the case of the simple treatment with H2O2 alone. In parallel, high biocompatibility of both pristine and f-MoS2 nanosheets is found up to 100 mu g mL(-1) in both cell lines (HeLa and Raw264.7) and primary immune cells. In addition, no immune cell activation and minimal pro-inflammatory cytokine release are observed in RAW264.7 and human monocyte-derived macrophages, suggesting a negligible cellular impact of such materials. Furthermore, the effects of degraded MoS2 and partially degraded f-MoS2 products on cell viability and activation are studied in cancer and immune cells. A certain cytotoxicity is measured at the highest concentrations. Finally, to prove that the cellular impact is due to cell uptake, the internalization of both pristine and functionalized MoS2 in cancer and primary immune cells is assessed.