Bi2S3 coated Au nanorods for enhanced photodynamic and photothermal antibacterial activities under NIR light

Abstract Antimicrobial nanostructures are expected to be effective alternatives to antibiotics, combating the emergence of drug resistance and superbugs. Herein, we have developed an intermediate layer conversion strategy to fabricate urchin-shaped Au@Bi2S3 core-shell structures via a hard template engaged polyol method, which showed low cytotoxicity and excellent photothermal conversion properties. This metal-semiconductor composite nanostructures are also behaved as the typical Schottky junction that can improve the separation efficiency of the electron-hole pairs triggered by near-infrared (NIR) light, leading to considerable generation of reactive oxygen species (ROS). As a result, the obtained urchin-shaped Au@Bi2S3 core-shell structures exhibited enhanced antibacterial ability compared to Au nanorods or Bi2S3 alone, which can be attributed to the higher yield of ROS and hyperthermia. Once stimulated by 808 nm laser irradiation, urchin-shaped Au@Bi2S3 core-shell structures made a nearly 100% bactericidal ratio quickly for Escherichia coli (140 μg/mL) and Staphylococcus aureus (120 μg/mL) owing to their synergetic photothermal and photodynamic anti-bacterial (PTA/PDA) performance. Thus, this work can be extended to fabricate some other heterostructures comprised of semiconductors and metals/semiconductors. In particular, the urchin-shaped Au@Bi2S3 core-shell structures is a promising candidate for rapidly bacterial elimination in medical treatment or environmental remedy.