Fast One-Step Synthesis of Biocompatible ZnO/Au Nanocomposites with Hollow Doughnut-Like and Other Controlled Morphologies

Hollow doughnut-like ZnO/Au nanocomposites have been synthesized through a fast one-step microwave-assisted hydrothermal route. The formation mechanism of the product is closely connected with the coordination and selective adsorption effect of trisodium citrate (TSC). Other different structures, such as ZnO nanorods/Au nanoparticles, ZnO nanodisks/Au nanoparticles, and ZnO nanospheres/Au nanoparticles have also been obtained in control experiments. The UV–vis and photoluminescence properties of the as-prepared hollow structures with different Au concentrations showed tunable UV and visible emission intensity. The hollow ZnO/Au nanocomposites are photostable with a strong resonance Raman signal. The colorimetric 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assays showed that ZnO/Au nanomaterials have low biological cytotoxicity on human colon cancer cells (LOVO cells) at the concentration of 50 μg/mL. The as-prepared ZnO/Au nanocomposites with good biocompatibility may have potential applications in biomedicine and biosensors.