Fabrication, characterisation and antimicrobial application of the ZnO@fGO nanocomposite

Herein, ZnO@fGO nanocomposites were fabricated via the sol-gel method by immobilising ZnO nanoparticles onto 3-aminopropyl triethoxysilane (APTES)-functionalised graphene oxide for antibacterial applications. FTIR confirmed effective interfacial bonding through Zn-O-Si, Si-O-C, and Si-O-Si vibrations, while revealing C/O ratios of 1.89 for TGO and 2.28 for commercial GO, indicating higher oxidation in the Tour-derived material. TEM showed sheet-like graphene oxide uniformly decorated with spherical and hexagonal ZnO nanoparticles, and Raman spectroscopy confirmed preservation of the graphitic framework with increased disorder after functionalisation and ZnO incorporation. The SEM-EDS verified the presence of C, O, Zn, and Si, and XRD confirmed the coexistence of amorphous GO and crystalline ZnO. Antibacterial activity was evaluated using resazurin-based minimum inhibitory concentration (MIC) assays against six Gram-positive and six Gram-negative bacteria. The optimised 50 wt% ZnO@fGO nanocomposite exhibited broad-spectrum antibacterial activity, with MICs largely at 250 μg/mL, and enhanced sensitivity against Gram-positive Staphylococcus aureus ( S. aureus) , Enterobacter cloacae ( E. cloacae) , and Gram-negative Proteus mirabilis ( P. mirabilis) (15.6–125 μg/mL). Comparable MICs to pristine GO and ZnO confirm that nanoparticle immobilisation preserved antibacterial efficacy. These findings highlight ZnO@fGO nanocomposites as stable and functional antimicrobial materials for mitigating bacterial persistence and AMR risks in wastewater treatment applications. • ZnO@fGO exhibited broad-spectrum antibacterial activity with MIC of ≤250 μg/mL. • ZnO and fGO presented the synergistic antibacterial mechanisms. • FGO improved ZnO dispersion and reduced nanoparticle agglomeration. • TGO exhibited enhanced antibacterial performance compared to the commercial SGO. • The 50% w/w ZnO@fGO offered the optimal ratio of ZnO:GO and nanoparticle dispersion.