NEEM-DRIVEN GREEN SYNTHESIS OF MULTIFUNCTIONAL COPPER NANOPARTICLES: A SUSTAINABLE APPROACH WITH BROAD-SPECTRUM ANTIMICROBIAL ACTIVITY

Abstract

The rise of antibiotic-resistant pathogens and the environmental issues linked to traditional nanoparticle production methods call for sustainable alternatives. This research presents an eco-friendly method for synthesizing copper nanoparticles (CuNPs) using Azadirachta indica (neem) leaf extract as a natural reducing and stabilizing agent. The successful synthesis was indicated by a noticeable color change from blue to dark green, due to surface plasmon resonance (SPR). Optimization studies determined the optimal conditions to be 10 mL of neem extract, a temperature of 60°C, a duration of 2 hours, and a neutral pH. Detailed characterization showed that the nanoparticles were spherical and well-dispersed, with an average diameter of 34.2 nm (SEM), a crystalline face-centered cubic structure with a crystallite size of 18.4 nm (XRD), and a distinctive SPR peak at 552 nm (UV-Vis). The CuNPs synthesized with neem demonstrated significant antimicrobial activity against Staphylococcus aureus (ZOI: 18 mm; 82% of amoxicillin) and Aspergillus fumigatus (ZOI: 17 mm; 81% of clotrimazole), greatly surpassing the crude neem extract (8 mm and 7 mm, respectively; p < 0.01). In addition to their antimicrobial properties, the CuNPs showed potential for catalytic dye degradation and antioxidant activity. This green synthesis method aligns with the principles of green chemistry and several UN Sustainable Development Goals (SDG 6, 12, 13), providing a cost-effective and environmentally sustainable platform for applications in biomedical coatings, wound healing formulations, food packaging, and wastewater treatment.