Precisely photothermal controlled releasing of antibacterial agent from Bi2S3 hollow microspheres triggered by NIR light for water sterilization

Microbial contamination in water has evoked worldwide attention owing to their greatest threats to the public safety. In this work, the sea urchin-like Bi2S3 hollow microspheres have been synthesized by a hard template-assisted polyol method using ZnS composite microspheres as sacrificed template on the large scale, which shows good biocompatibility and photothermal conversion properties. Thermal-sensitive biocompatible 1-tetradecanol (TD) combined antibacterial agents (Linalool) were loaded into the hollow cavity of the sea urchin-like Bi2S3 hollow microspheres to form TD/Linalool@Bi2S3 composites. The Bi2S3 in the TD/Linalool@Bi2S3 composites can convert the absorbed NIR energy into heat energy under the irradiation of near infrared (NIR) light, which would make the temperature to reach the melting point of the TD and Linalool can be released at same time. Thus, the antibacterial agent Linalool can be precisely controlled releasing from the formed TD/Linalool@Bi2S3 composites, which provided rapid and effective killing outcome in vitro for Gram-negative Escherichia coli (E. coli) and Gram-positive Stahylococcus aureus (S. aureus). Additionally, the as-prepared TD/Linalool@Bi2S3 composites exhibited superior antibacterial ability as compared to antibacterial agent treatment or photothermal therapy (PIT) alone, which can be attributed to the synergistic effects of the NIR light driven photothermal killing and antibacterial agent releasing. It endowed that the designed TD/Linalool@Bi2S3 composites is a promising antibacterial platform for cleaning the microbial contaminated water environment, which is of great strategic significance and remains a formidable challenge for practical applications.