Microwave-assisted graphene oxide/carbon spheres with silver nanoparticles: dual catalyst for peroxide detection and antibacterial use

In this study, a novel nanocomposite was rationally engineered by embedding silver nanoparticles (AgNPs) into tannic acid-derived carbon spheres (Cs), followed by their distribution on graphene oxide (GO) sheets (AgNPs@Cs-TA@GO), aiming to enhance catalytic and antibacterial performance. The fabrication process was expedited using a microwave-assisted technique. The AgNPs@Cs-TA@GO nanocomposite with the core based on AgNPs with an average diameter of 21 nm showed significant peroxidase-like activity by oxidizing 3,3',5,5'-tetramethylbenzidine to its oxidized form in the presence of H₂O₂. This compassionate H₂O₂ colorimetric detection allowed for quick identification of H₂O₂ in a broad range (0.6-9.0 ppm) with a low detection limit of 0.2 ppm (<i>S</i>/<i>N</i> = 3). The viability of this method was confirmed by qualitatively detecting H₂O₂ residual in aquaculture water samples. Additionally, the antibacterial assays, conducted using the agar well diffusion method demonstrated pronounced inhibitory effects against <i>Vibrio parahaemolyticus</i> ATCC 17802 (Gram-negative) and <i>Staphylococcus aureus</i> ATCC 25923 (Gram-positive), with inhibition zones of 46.1 and 49.3 mm, respectively. The rapid microwave-assisted incorporation of AgNPs into Cs within the GO network not only improves synthesis duration but also the catalytic and antibacterial performances as a result of minimized coagulation and promoting electron transfer on the AgNPs' surface.