CuS nanoparticles anchored to g-C3N4 nanosheets for photothermal ablation of bacteria.

Antibiotic resistance has already been recognized as one of the greatest threats to human beings' health, and thus it is highly desirable to develop new bactericidal approaches. The photothermal antibacterial process based on the photo-to-thermal conversion using semiconducting materials is currently extensively studied owing to its high efficiency, long durability and environmental benignity. In this study, we fabricated copper sulfide (CuS) nanoparticle-decorated graphitic carbon nitride (g-C3N4) nanosheets, denoted as the PEG-CuS@g-C3N4 nanocomposite, via a simple hydrothermal process. Materials characterization showed that CuS nanoparticles were uniformly distributed on the surface of g-C3N4 without agglomeration. Moreover, the nanocomposite exhibited excellent photothermal conversion efficiency (up to 59.64%) due to its strong near-infrared (NIR) absorption characteristics. The antibacterial efficiency evaluation indicated that the PEG-CuS@g-C3N4 nanocomposite could effectively kill the Gram-positive Staphylococcus aureus (S. aureus) and the Gram-negative Escherichia coli (E. coli). We found that up to 99% of both S. aureus and E. coli could be killed in a 200 μg ml-1 PEG-CuS@g-C3N4 suspension within 20 min of NIR irradiation. Moreover, the cytotoxicity of the PEG-CuS@g-C3N4 nanocomposite was evaluated using the mouse skin fibroblast NIH-3T3 cells, and the nanocomposite was found to display acceptable biocompatibility. We believe that the PEG-CuS@g-C3N4 nanocomposite is of significant interest for rapid bacteria-killing, and would gain promising applications for sterilization.