Photocatalytic Preparation and Antibacterial Activity of GO@Au Nanocomposites

A composite material composed of graphene oxide(GO) and gold nanoparticles was synthesized via photocatalytic method. The research results indicate that the size of the Au nanoparticles can be controlled by adjusting the illumination time. When the illumination time is less than 20 min, the absorption spectrum of the GO and Au nanohybrids does not exhibit any significant absorption peaks, suggesting the formation of GO loaded Au nanoclusters(GO@Au NCs). As the illumination time increases, an absorption peak appears at 540 nm, indicating an increase in the size of the Au nanoparticles and the formation of GO loaded Au nanoparticles(GO@Au NPs). Furthermore, since the photogenerated electrons from GO are utilized to reduce Au(3+ )to form Au nanoparticles, a large number of oxidative functional groups in GO are preserved, endowing both GO@Au NCs and GO@Au NPs with excellent hydrophilicity. Notably, the antibacterial performance of Au nanoparticles is closely related to their size. GO@Au NCs demonstrated outstanding antibacterial properties, with a bacterial inhibition rate against Staphylococcus aureus as high as 99%. In contrast, GO@Au NPs showed hardly significant antibacterial effect. This is attributed to the high specific surface area and high defect states of GO@Au NCs, which favor the generation of reactive oxygen species(ROS).