Antibacterial Activity of Undoped and (Zn, Co) Co-Doped CuO Nanostructure Prepared by Hydrothermal Technique

In the past few years, there has been a significant focus on the utilization of copper oxide in the field of biological applications, due to its low toxicity and biocompatibility. Pure, Zn-doped, and Zn/Co–co-doping CuO cauliflowers with large surface area were created using hydrothermal technique with varying Co condensation (1%, 2%, and 3%), along with a constant Zn concentration. The structural, surface morphology, and optical characteristics of pure, Zn-doped, and Zn/Co co-doped copper oxide were investigated. The incorporation of Zn and Co into copper oxide was found to have a notable impact on the size of the crystallite, lattice parameters, and the sample band gap energies. XRD analysis revealed a covellite monoclinic polycrystalline form featuring a (\({1}^{-}\) 11) favored direction across all samples. FE-SEM examination confirmed the formation of CuO nanoparticles displaying a cauliflower-shaped hierarchical structure. Optical measurements yielded principles of the optical gap falling within the range of 2.58–1.67 eV. The antimicrobial efficacy of pure CuO, Zn-doped CuO, and Zn/Co co-doped CuO against S. aureus and E. coli strains was evaluated through inhibition zone assays. While all samples displayed notable antibacterial properties, the 3% Zn/3% Co co-doping CuO exhibited the strongest antibacterial activity, with a maximum inhibitory concentration of 12 mg/ml, against both gram-positive and gram-negative microorganisms. Furthermore, the antibacterial activity showed that the inhibition zone of Zn/Co co-doped CuO was 13–19 mm for E. coli and 15–20 mm for S. aureus at a high concentration of Fe dopant.