Green Synthesis of CuO Nanoparticles from Electronic Waste Using Mesosphaerum suaveolens and their Antibacterial Activity against Fish Pathogens

The increasing accumulation of electronic waste (e-waste) and the developing demand for sustainable nanomaterials have propelled the development of eco-friendly synthesis practices. In this current study, copper oxide nanoparticles (CuO NPs) were synthesized using copper derived from e-waste (sim card) in combination with plant extract from Mesosphaerum suaveolens through a green synthesis pathway. Characterization of the synthesized nanoparticles was showed using UV–Visible spectroscopy, Fourier Transform Infrared (FTIR) spectroscopy, Scanning Electron Microscopy (SEM), and X-ray Diffraction (XRD) analysis. The UV–Vis analysis showed a characteristic absorption peak in the range of 220–240 nm, thereby confirming the formation of nanoparticles. FTIR results suggested the involvement of phytochemicals, including phenolics, proteins, and flavonoids, in both the reduction and stabilization of CuO NPs, with a distinct Cu–O stretching band recognized at 600–450 cm⁻¹. SEM analysis shown irregular, agglomerated nanostructures with mixed morphologies, comprising rod-like and flake-like shapes, and exhibiting particle sizes between 80 and 200 nm. The XRD patterns verified the formation of highly crystalline, monoclinic CuO nanoparticles with an average crystallite size of 15–35 nm and high phase purity. The antibacterial activity of the synthesized CuO NPs was measured against the fish pathogen Streptococcus agalactiae. The nanoparticles demonstrated significant antibacterial activity in a dose-dependent manner, with the highest zone of inhibition recorded at 100 µg/kg concentration, while no inhibition was noted in the control group. This study underscores a sustainable approach to transforming e-waste into value-added nanomaterials and proves the potential use of green-synthesized CuO nanoparticles as active antimicrobial agents in aquaculture.