Green Synthesis, Characterization and Anti-Bacterial Studies of Copper Oxide Nanoparticles Using Croton scabiosus Bedd. Fruit Extract

The development of eco-friendly, cost-effective methodologies for the biosynthesis of metal oxide nanoparticles represents a primary objective in contemporary green nanoscience. The present study reports the biogenic synthesis of copper oxide nanoparticles (CUONPS) employing the aqueous fruit extract of Croton scabiosus Bedd. (Euphorbiaceous). This species is a rare, endemic, and IUCN Vulnerable tree species which can act as both reducing and capping agents for the nanoparticles.  1 mM copper nitrate (Cu (NO₃) ₂) solution was titrated with the fruit extract in a volume ratio of 4:1 (v/v) at room temperature. The progressive color change from green to dark brown within 24–48 hours confirmed the transition of Cu⁺2 ions and formation of CUONPS, which were subjected to various characterization techniques for confirmation of their physical and chemical properties.  UV–Vi’s spectroscopy revealed a characteristic absorption peak at 274 nm with an optical band gap of 2.65 eV. FTIR analysis confirmed Cu–O lattice vibrations and phytochemical capping. XRD established a simple cubic crystalline phase.  DLS revealed a mean hydrodynamic diameter of 19.3 nm (PDI: 0.329) and zeta potential of −13.2 mV. The CUONPS demonstrated potent antimicrobial activity against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Bacillus subtilis, with maximum zone of inhibition of 42 ± 0.1 mm against S. aureus at 200 µg/mL, but very less activity against fungal strains. Hence, the CUONPS from C. scabiosus fruit are potential antibacterial agents against various bacterial strains and can be used in pharmaceutical applications.