Photogenerated Charge Carriers in Molybdenum Disulfide Quantum Dots with Enhanced Antibacterial Activity

Molybdenum disulfide (MoS2) nanosheets have received considerable interest due to their superior physicochemical performances to graphene nanosheets. As the lateral size and layer thickness decrease, the formed MoS2 quantum dots (QDs) show more promise as photocatalysts, endowing them with potential antimicrobial properties under environmental conditions. However, studies on the antibacterial photodynamic therapy of MoS2 QDs have rarely been reported. Here, we show that MoS2 QDs more effectively promote the creation and separation of electron hole pair than MoS2 nanosheets, resulting in the formation of multiple reactive oxygen species (ROS) under simulated solar light irradiation. As a result, photoexcited MoS2 QDs show remarkably enhanced antibacterial activity, and the ROS-mediated oxidative stress plays a dominant role in the antibacterial mechanism. The in vivo experiments showed that MoS2 QDs are efficacious in wound healing under simulated solar light irradiation and exert protective effects on normal tissues, suggesting good biocompatibility properties. Our findings provide a full description of the photochemical behavior of MoS2 QDs and the resulting antibacterial activity, which might advance the development of MoS2-based nanomaterials as photodynamic antibacterial agents under environmental conditions.