Superb photo-antibacterial/antibiofilm activities of BP/WS₂ and BP/MoS₂ nanocomposites under near-infrared irradiation

Abstract

The development of multifunctional antibacterial materials based on semiconductor materials has become the focus of treatment in the field of antibiotic-resistant bacteria. Here, for the first time, the superb photocatalytic/photothermal antibacterial activity of BP/MoS2 and BP/WS2 nanocomposites against both E. coli and S. aureus under near-infrared (NIR) or light-emitting diode (LED) illumination was demonstrated. Characterization studies using advanced instrumental techniques confirmed the successful formation of BP/WS2 and BP/MoS2 S-scheme heterojunctions with distinct structural, morphological, and compositional features. Moreover, it was verified that the enhanced photo-antibacterial activity of both heterojunctions compared to their pristine analogs was demonstrated to be due to the synergistic interactions at the atomic level elucidated by Mo/W-S-P via a sulfur atom bridge in X-ray photoelectron spectroscopy analysis, which improves the charge flow and enhances the photocatalytic performance. Optical density measurements were performed to obtain bacterial growth over 4 h, where BP/WS2 (congruent to 88%) and BP/MoS2 (congruent to 83%) showed higher NIR light-driven antibacterial activity compared to the pristine analogs (BP nanosheets, WS2 or MoS2 nanostructures), which is attributed to the S-scheme heterojunctions formed between BP and MS2 that enhance the production of ROS by promoting the use of light-induced carriers. The photo-antibacterial activities of BP/WS2 and BP/MoS2 heterojunctions reached 93% and 98%, respectively. The bacterial mechanical rupture effect of BP/WS2 and BP/MoS2 heterojunctions was monitored using SEM and E. coli was found to be more resistant to damage than S. aureus. The ability of BP/WS2 and BP/MoS2 to generate reactive oxygen species (ROS) was better than that of pristine BP nanosheets, as demonstrated by a glutathione (GSH) oxidation assay. The photothermal activities of the nanocomposites were investigated to explain the photoinduced antibacterial mechanism. In addition, the photo-antibiofilm activities of BP/WS2 and BP/MoS2 heterojunctions were also investigated and the biofilm structure of S. aureus was almost completely eradicated under LED light irradiation.