UV-Assisted Room-Temperature Fabrication of Lignin-Based Nanosilver Complexes for Photothermal-Mediated Sterilization

Green and controllable preparation of silver nanoparticles (AgNPs) remains a great challenge. In this work, ethanol-extracted lignin-based nanosilver composites (AgNPs@EL) were synthesized at room temperature with the assistance of ultraviolet (UV) radiation. The ethanol-extracted lignin (EL) could serve as natural dispersion carriers and reducing agents for AgNPs. The reducing ability of EL could be further improved under UV irradiation, which enables the rapid synthesis of AgNPs at room temperature. More importantly, due to the good photothermal conversion capacity of EL, AgNPs@EL exhibits remarkably enhanced photothermal performance and excellent photothermal antibacterial ability, which could cause 7.2 and 5.3 log₁₀ CFU/mL reduction against Escherichia coli and Staphylococcus aureus, respectively, under near-infrared (NIR) irradiation (808 nm, 1.8 W/cm²) for 5 min. Furthermore, the composite film obtained by impregnating bacterial cellulose onto AgNPs@EL solution also shows significantly improved mechanical properties and photothermal antimicrobial activity. Therefore, this work may provide insights into the design of lignin-based photothermal-mediated antimicrobial materials.