Evaluation of antibacterial behavior of in situ grown CuO-GO nanocomposites

The growth of harmful microorganisms is a severe threat to human life. Nowadays, it is necessary to prepare antimicrobials materials with high biocompatibility properties. Hence, the use of nanomaterials and their nanocomposites has been proposed as a suitable way to obtain safe and potent antibacterial materials. Recently, several studies have been conducted on the antibacterial properties of metal oxide and graphene oxide (GO) nanomaterials individually. This study investigated the synergistic effect of GO and copper oxide (CuO) as a nanocomposite. CuO-GO nanocomposite containing 5%, 15%, 25%, 50%, and 75% of GO were synthesized to study antibacterial properties. X-ray diffraction (XRD) results showed that CuO and GO synthesized were free of impurities and unwanted phases. Fourier Transform Infrared Spectroscopy (FTIR) spectrum of the prepared sample has revealed the presence of vibrational modes related to Cu-O, alkoxy group (O-H), epoxy group (C-O-C), and carboxyl group (C-O). In Raman spectroscopy, the CuO nanostructure has a redshift, and in the CuO-GO nanocomposite, D band and G band have blueshift and redshift by increasing the amount of GO, respectively. The results of UV-Vis spectra showed that synthesized CuO and GO have a higher band gap (4.54 eV and 3.03 eV, respectively) than previous studies. Also, the highest amount of band gap of nanocomposites is related to the 50%wt GO nanocomposite (3.40 eV). Field emission scanning electron microscope (FESEM) images showed that CuO nanosheets bonded with GO plates and decorated the GO plates. Antibacterial activity of synthesized nanocomposite investigated using Escherichia coli (E.coli) bacteria. The antibacterial test results showed that CuO nanoparticles have inadequate antibacterial activity (15%), while by composting with GO, the antibacterial activity against E. coli significantly increased (for 50% GO about 76%). However, the antibacterial activity reduced to 68% for the nanocomposite sample with 75% GO concentration; thus, 50% GO nanocomposite is the optimal concentration.