Graphene oxide-modified ZnO particles: synthesis, characterization, and antibacterial properties

Abstract

Nanosized ZnO particles with diameters of 15 nm were prepared with a solution precipitation method at low cost and high yield. The synthesis of the particles was functionalized by the organic solvent dimethylformamide, and the particles were covalently bonded to the surface of graphene oxide. The morphology of the graphene oxide sheets and ZnO particles was confirmed with field emission scanning electron microscopy and biological atomic force microscopy. Fourier transform infrared spectroscopy and X-ray diffraction were used to analyze the physical and chemical properties of the ZnO/graphene oxide composites that differed from those of the individual components. Enhanced electrochemical properties were detected with cyclic voltammetry, with a redox peak of the composites at 0.025 mV. Excellent antibacterial activity of ZnO/graphene oxide composites was observed with a microdilution method in which minimum inhibitory concentrations of 6.25 µg/mL for Escherichia coli and Salmonella typhimurium , 12.5 µg/mL for Bacillus subtilis , and 25 µg/mL for Enterococcus faecalis . After further study of the antibacterial mechanism, we concluded that a vast number of reactive oxygen species formed on the surface of composites, improving antibacterial properties.

Recent Advances in Zinc Oxide Nanostructures with Antimicrobial Activities

“…In contrast, GO sheet and ZnO NPs exhibited a higher MIC value of 12.5 and 50 µg/mL respectively against E. coli and S. typhimurium. In other words, GO/ZnO hybrid caused more damage to E. coli and S. typhimurium than GO and ZnO NPs alone [240]. Excellent antibacterial activity of GO/ZnO hybrid was attributed to the synergistic effects of GO and ZnO NPs.…”

“…The formation of GO/ZnO nanocomposites is now considered. GO prepared by a modified Hummers process is thoroughly mixed with the solution of zinc salt and alkali hydroxide using either water or organic solvent [240]. The resulting solution is then treated hydrothermally [173,241], or solvothermally [242][243][244][245].…”

“…The resulting solution is then treated hydrothermally [173,241], or solvothermally [242][243][244][245]. The oxygenated groups of GO are largely removed from graphene sheet during heating, leading to the formation of RGO [172,240,241,244]. In a certain case, ZnO NPs synthesized from co-precipitation is added directly to the GO solution [246].…”

“…Furthermore, graphene sheets with a lateral dimension of several micrometers served as a blanket to wrap bacteria completely, thus isolating bacterial strains from external environment and limiting their access to nutrients [13]. In this respect, finely dispersed ZnO NPs on GO inactivated those bacterial strains through the release of Zn 2+ ions and the production of ROS [240]. As such, GO sheet caused LPO while ZnO NPs induced ROS, resulting in the GO/ZnO hybrid with superior antibacterial activity (Table 1).…”

Two Different Acid Oxidation Syntheses to Open C60 Fullerene for Heavy Metal Detection

“…In both FT-IR spectra the typical peaks of graphene oxide that are related to the carboxyl, hydroxyl, and epoxy groups of GOQDs are present. In particular, the peaks at approximately 1,000 cm -1 , 1,150 cm -1 , 1,650 cm -1 , 1,750 cm -1 , and 3,350 cm -1 corresponding to C-O, C-OH, C=C, C=O and O-H, respectively [30].…”