Fabrication, structural analysis, and bioactivity assessment of a novel reduced graphene oxide reinforced ternary metal oxide (rGO-ZnO-SnO2-Fe2O3) nanocomposite

Abstract

The goal of the current research was to prepare an effective hybrid material, which was expected to counter antibiotic-resistant bacterial strains and stabilize generated free radicals. For this purpose, ZnO-SnO₂-Fe₂O₃ (ZSF) and rGO-ZnO-SnO₂-Fe₂O₃ (rGO-ZSF) nanocomposites were synthesized and were calcined at 450 °C. Initially, GO was synthesized via a modified Hummers' method from commercially available graphite flakes and a chemical precipitation method was used to synthesize ZSF and rGO-ZSF nanocomposites. Fourier-transform infrared spectroscopy was conducted to analyze the chemical compositions of all synthesized samples. Morphological examinations were made via scanning electron microscopy, where the metal oxide was seen to implant in the GO sheets, and the average particle size for ZSF is 16.02 nm and for rGO-ZSF is 22.5 nm. Crystallographic properties, i.e. crystallite sizes, lattice strain, dislocation density (ρ) and microstrain (ε), were extracted using an X-ray diffractometer, showing a clear variation in the crystallite sizes and microstrain. The antibacterial activities of the synthesized samples were assessed against Gram-positive (G +ve) and Gram-negative (G −ve) microorganisms using the agar well diffusion technique. rGO-ZSF has significantly higher antibacterial activity than pure GO and the ZSF nanocomposite. When compared to G −ve bacteria, G +ve bacteria showed more resistance to the samples; this might be due to differences in the cell wall composition. Upon increasing the sample dose in the system, activity was observed to rise. Likewise, these samples were also employed as stabilizing agents against ABTS and DPPH free radicals, and the highest activity was achieved at higher concentrations. The IC₅₀ values show that the synthesized samples showed more activity against DPPH as compared to ABTS free radicals.