Berberis aristata root extract-mediated biosynthesis of CuO-rGO nanocomposites for potential antibacterial activity

The current work demonstrates a green wet-chemical synthesis method for synthesizing reduced graphene oxide (rGO), copper oxide nanoparticles (CuO NPs), and CuO–rGO nanocomposites (NCs) utilizing Berberis aristata root extract at low temperature (70 °C). Comprehensive characterization using XRD, UV–vis spectroscopy, and SEM confirmed the structural integrity and successful formation of the NPs and NCs. Thereafter, antibacterial activity is examined against both gram-negative ( E. coli , K. pneumoniae , P. vulgaris ) and Gram-positive ( S. agalactiae , S. aureus , S. pyogenes ) bacterial strains at three different concentrations. Among the synthesized materials, rGO (R3, 5 mg/ml) demonstrated effective antibacterial activity, particularly against K. pneumoniae , showing a zone of inhibition (ZID) of ∼23 mm. This is attributed to the reduced oxygen functionalities, which enhance ROS generation and disrupt bacterial membranes. While CuO NPs (CU3, 5 mg/ml) exhibited moderate antibacterial performance, with a ZID of ∼16 mm against P. vulgaris , indicating the influence of surface properties on antimicrobial efficacy. Remarkably, the CuO–rGO NCs (CG3, 5 mg/ml) exhibited significantly enhanced and broad-spectrum antibacterial activity and displayed the highest efficacy against P. vulgaris with a ZID of ∼40 mm. This improved performance is a result of the synergistic interaction between CuO and rGO, leading to enhanced bacterial membrane adhesion, sustained Cu²⁺ ion release, and increased ROS production. These findings highlight the CuO-rGO NCs, especially CG3, as a promising, eco-friendly, and potent antibacterial platform. Their potential for clinical and environmental applications warrants further exploration through in vivo studies and formulation optimization.