Defect-Engineered Functionalized MoS2 Quantum Dots with Enhanced Antibacterial Activity

The rapid development of multidrug-resistant bacterial strains creates a global threat and warrants advanced strategies to control infectious diseases. Surface-modified two-dimensional molybdenum disulfide (MoS2) nanomaterials have great potential to eradicate pathogenic bacteria. In MoS2 nanosheets, the presence of atomic defects plays a crucial role in determining their physical and electronic properties. The presence of defects not only improves the extent of surface modification but also affects the generation of reactive oxygen species (ROS), which play a pivotal role in antibacterial activity. Hence, the facile preparation of MoS2 nanomaterials with a controlled degree of defects would prompt their utilization as an efficient antibacterial agent. Herein, we have demonstrated the preparation of different defect-engineered MoS2 quantum dots (QDs), followed by surface modification with thiol ligands. The extent of ligand conjugation on the MoS2 QDs highly depends on the degree of defects, and that can also enhance the aqueous stability. The functionalized MoS2 QDs possessing a higher degree of defects showed remarkably high antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA) compared to the lower defect-containing MoS2 QDs. This is due to the generation of a large amount of ROS along with the increased cellular interactions of functionalized MoS2 QDs. This could potentially disrupt the bacterial cell membrane integrity to show enhanced bactericidal activity. The MRSA bacterial growth has been completely suppressed in the presence of only 0.65 μg/mL of functionalized MoS2 QDs.