Synthesis, Characterization and Antimicrobial Activities of Copper Nanoparticles from Avocado Pear Peels

ABSTRACT This study explores the green synthesis and characterization of copper nanoparticles (CuNPs) using waste avocado pear peels and evaluates their antimicrobial activity. The peels, rich in bioactive compounds such as polyphenols, flavonoids, and organic acids, acted as both reducing and capping agents. UV-Visible spectroscopy of the peel extract showed a strong absorbance at 300 nm, indicating the presence of antioxidant compounds like flavonoids and phenolics. The synthesized CuNPs exhibited a surface plasmon resonance (SPR) peak at 550–600 nm, confirming their formation and optical stability.FTIR analysis revealed prominent peaks at 3300–3400 cm⁻¹ (O–H stretching), 1700 cm⁻¹ (C=O stretching), and 1000–1200 cm⁻¹ (C–O stretching), indicating the involvement of hydroxyl, carbonyl, and ether groups in nanoparticle stabilization. These functional groups are consistent with previous studies on avocado-based phytochemical extracts. SEM analysis demonstrated that the nanoparticles were predominantly spherical with rough surfaces and slight agglomeration, typical of phytochemically mediated nanoparticle synthesis. EDX analysis confirmed the elemental composition, showing significant peaks for carbon, oxygen, and copper, reflecting the organic and metallic content of the biosynthesized CuNPs.XRD analysis showed sharp diffraction peaks, indicating a crystalline nature of the nanoparticles, and matched standard copper oxide patterns. These results confirm the successful synthesis of stable, crystalline CuNPs using avocado peel extract.Antimicrobial tests revealed that both the extract and CuNPs inhibited the growth of E. coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Streptococcus pneumoniae, with CuNPs showing superior activity. This work highlights an eco-friendly approach to synthesizing effective antimicrobial agents from agricultural waste, contributing to sustainable nanotechnology and biomedical innovation.