BP/MoS₂ heterojunction is prepared by solvothermal method using NMP, BP nanosheets and (NH₄)₂MoS₄. Under NIR irradiation, BP/MoS₂ can be heated up to 51.8 °C within 5 minutes by photothermal conversion. In addition, the existence of ⋅O₂ ⁻ and ¹O₂ in BP/MoS₂-NIR system is verified to sterilize efficiently. With a loading content of 10 wt % MoS₂, bacterial cells, especially drug-resistant bacteria (10⁶ cfu ⋅ mL⁻¹) completely can lose the viability within 10 min of NIR irradiation.

Abstract

In this research, a high-efficiency nano-fungicide with synergistic effect was obtained by combining polycrystalline MoS₂ with layered nano-BP to form heterojunction, which had a new photothermal-photocatalytic antibacterial mechanism to Gram-positive bacteria, Gram-negative and drug-resistance bacteria under NIR. BP/MoS₂ whose lethality of bacteria could reach nearly 100 % at 400 μg/L, exhibited the highest photothermal lysis efficiency against E. coli, B. pumilus and A. baumannii. It was found that the heterojunction could be heated up to 51.8 °C within 5 minutes by photothermal conversion, and it also had an excellent performance of photothermal cycle. High temperature and stability of the material endowed it with an outstanding and long-lasting bactericidal effect. In addition, a series of in vitro free radical experiments was designed, the existence of ⋅O₂ ⁻ and ¹O₂ in BP/MoS₂-NIR system was verified. And the Way of ROS production and the mechanism of action were discussed by EPR test. Subsequently, two mechanisms of synergistic antibacterial action were summarized, that is, abundant ROS and high temperature could destroy cell wall damage and lysis of bacteria effectively. This study provides a theoretical basis for the synergistic antibacterial action of NIR photothermal and photocatalysis of BP system.