Eco-friendly method for synthesis of zeolitic imidazolate framework 8 decorated graphene oxide for antibacterial activity enhancement

Abstract

We report a rapid method for synthesis of zeolitic imidazolate framework 8 (ZIF-8)-decorated graphene oxide (GO) composites (ZGO) with good antibacterial properties. The ZGO composites were synthesized at room temperature with low GO to metal salt ratios. The samples were characterized by X-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy, thermal gravimetric analysis, and surface area analysis. The characterization results show that ZIF-8 with a size of approximately 120 nm is successfully decorated on the surface of GO sheets with the host ZIF-8 framework maintained in the synthesized composite, but there is a significant reduction in the Brunauer–Emmett–Teller surface area. The antibacterial activities of the samples against Escherichia coli ATCC 11229 and Staphylococcus aureus ATCC 6538 as model strains of gram-negative and -positive bacteria, respectively, were determined by disc diffusion and minimum inhibitory concentration (MIC) tests. ZGO-1.0 (1 wt% of ratio of GO to metal salt) shows the highest antibacterial activity with MIC values required to inhibit bacterial growth of E. coli and S. aureus of 5 times lower than those of pristine ZIF-8. Different antibacterial mechanisms are proposed based on field-emission scanning electron microscope images of the two bacteria after contact with the synthesized composite. Overall, owing to the simple synthesis, good stability, low chemical usage, and excellent antibacterial activity of the ZGO composites, they show great potential for application in the field of microbial contamination control.