Near-Infrared-Activated Efficient Bacteria-Killing by Lignin-Based Copper Sulfide Nanocomposites with an Enhanced Photothermal Effect and Peroxidase-like Activity

Lignin has been considered to be an ideal carrier for the construction of lignin-based antibacterial materials by its biocompatibility and environmentally benign feature. Herein, lignosulfonate (LS) was utilized as a growth template and a stabilizing agent to synthesize lignin-copper sulfide (LS-CuS) nanocomposites. Interestingly, the as-prepared LS-CuS nanocomposites show enhanced photothermal performance and peroxidase-like activity with near-infrared (NIR) light activation, which benefits highly efficient bacteria-killing via synergistic photothermal–catalytic effects. The bactericidal tests indicated that LS-CuS nanocomposites (100 μg/mL) cause 5.9-log10 and 5.4-log10 CFU/mL reductions against Escherichia coli and Staphylococcus aureus under NIR light irradiation (808 nm, 1.8 W/cm2) for only 5 min in the presence of H2O2. Moreover, LS-CuS nanocomposites can be blended with waterborne polyurethane (WPU) to obtain hybrid films, which also achieves a bactericidal efficacy of more than 90% in 5 min. Considering the low cost, easy preparation, and environmental friendliness of LS-CuS nanocomposites, this study may provide new insights into the design of lignin-based inorganic nanocomposites with high bacteria-killing efficiency in a sustainable manner.