Facile preparation of polyethyleneimine-conjugated silver sulfide nanoparticles as near-infrared-responsive to sterilization of multidrug resistant uropathogens, and cytotoxicity activity

We present the chemical synthesis of polyethyleneimine-conjugated silver sulfide nanoparticles (PEI/AS) utilizing an economical solvothermal synthesis method, aimed at developing effective alternative antibacterial agents. The antibacterial efficacy of the synthesized materials, both with and without the application of near-infrared (NIR) laser irradiation, was evaluated in vitro against two distinct clinically relevant multi-drug-resistant (MDR) uropathogenic strains: Escherichia coli and methicillin-resistant Staphylococcus aureus. The bactericidal effects induced by NIR light indicate that the PEI/AS nanoparticles possess an efficiency that is five times greater than that of Ag₂S alone. A suggested antibacterial mechanism posits that the wrapping of PEI increases electrostatic interactions, thereby facilitating the attachment of Ag₂S nanoparticles to the bacterial surface. This process leads to the disruption of the outer membrane through the generation of localized heat and an increased concentration of reactive oxygen species (ROS), including superoxide anions (·O₂^–) and hydroxyl radicals (·OH). In addition, the mechanism involves the regulated release of Ag⁺ ions when exposed to NIR light irradiation. The combined action led to an over 95.79% elimination of bacteria at a concentration as low as 50 μg mL⁻¹, which can be primarily ascribed to the regulated photothermal effect induced by 808 nm near-infrared light irradiation, demonstrating exceptional photothermal conversion efficiency. These results paves a way for manufacturing innovation in future.