Green Synthesis of Gold Nanoparticles with Good Photothermal Properties and Antibacterial Activity from Black Corncob Extract

Green synthesis of gold nanoparticles is an effective approach to create biocompatible nanomaterials. In this study, gold nanoparticles (BC-AuNPs) were prepared by reducing chloroauric acid with black corncob (BC) extract at relatively low temperatures. The optimal preparation conditions were obtained through a single-factor experiment, which included 5 mL of black corncob extract and 0.12 mL of 3% HAuCl4 solution at a pH of 5.0, and the reaction was carried out at 50 °C in a water bath for 3 h. The prepared BC-AuNPs were characterized by ultraviolet–visible (UV-Vis) spectroscopy, Fourier-transform infrared (FTIR) analysis, transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), dynamic light scattering (DLS), and Zeta-potential measurement, which showed that they were dispersed spherical particles with an average size of approximately 23.0 nm and their surfaces were covered with various black corncob active components. The photothermal performance test indicated a good photothermal effect with a conversion efficiency of 41.3%. Antibacterial experiments revealed that BC-AuNPs had excellent antibacterial activity. The minimum inhibitory concentrations (MICs) for E. coli and Salmonella were 25.00 and 50.00 µg/mL, respectively. Overall, this study proved a potential application for gold nanoparticles in photothermal antibacterial fields.