Defect-engineered Ag/ZnO and Ag2O/ZnO nanomaterials prepared with nanoparticles synthesized by a sustainable sol–gel method and their biological responses

ZnO/Ag and ZnO/Ag2O nanocomposites were produced using ZnO nanoparticles synthesized via a starch-mediated sol–gel method. XRD and Rietveld refinement confirmed the wurtzite-like structure of spherical 16-nm ZnO nanocrystals. These nanocrystals were further decorated with cubic nearly spherical 7-nm Ag and irregular 6-nm Ag2O nanocrystals, resulting in nanocomposites with distinct structural characteristics. The morphological analysis confirmed the distinct shapes and sizes of Ag, Ag2O, and ZnO nanoparticles. The nanocomposites exhibited a tuned optical bandgap and structural defects like V_Zn , VO, and V_O^+ . In vitro biological tests revealed that the Ag2O/ZnO nanocomposite displayed significantly enhanced antidiabetic, antimicrobial, and antioxidant activities. These enhanced biological properties were attributed in part to the unique morphology of Ag2O nanoparticles and the defective nature of ZnO/Ag2O nanocomposite. These results demonstrate that the green-synthesized ZnO nanoparticles decorated with Ag2O emerge as a promising material for biomedical applications.