An Exceptional Broad-Spectrum Nanobiocide for Multimodal and Synergistic Inactivation of Drug-Resistant Bacteria

This study reports the fabrication of a novel photothermal material formed via the physical blending of excess lauric acid (LA) and cupric acetate, followed by efficient ligand exchange. Surprisingly, the copper-LA complex exhibited a 12-fold enhancement of the molar extinction coefficient in the near-infrared (NIR) region relative to aqueous cupric acetate. Inspired by this interesting finding, we formulated these photothermal materials into colloidally dispersed nanoparticles via a technique that combined nanoprecipitation and in situ surface polymerization for antibacterial studies. The resultant nanoparticles exhibited rapid and stable photothermal responses to NIR irradiation, with a 4-fold enhanced photothermal conversion efficiency relative to aqueous cupric acetate. Since a positively charged monomer was incorporated during in situ surface polymerization, these positively charged nanoparticles were ingested efficiently and subsequently digested by drug-resistant bacteria. By combining the LA-mediated membrane-damaging effect, copper-mediated Fenton-like reaction, as well as the photothermal effect of the copper-LA complex, a broad-spectrum, multimodal, and synergistic antibacterial effect was achieved both in vitro and in vivo, with the killing efficiency up to 99.99% for ampicillin-resistant Escherichia coli (Amp' E. coli) and 99.9999% for methicillin-resistant Staphylococcus aureus (MRSA). Our newly developed nanobiocide represents a class of exceptional broad-spectrum antibacterial materials, holding great potential for treating drug-resistant infections in clinical settings. [GRAPHICS] .