Ecofriendly green synthesis, characterization and biomedical applications of CuO nanoparticles synthesized using leaf extract of Capsicum frutescens

Abstract The green technology is creating an interest among researchers as they are simple, ecofriendly, and also cost-effective especially in synthesizing nanoparticles. In the present study, CuO nanoparticles were synthesized by taking copper nitrate as precursor and using the leaf extract of Capsicum frutescens as capping and stabilizing agent. The visual observation of dark green color indicated the formation of CuO nanoparticles. The gas chromatograph illustrated the phytochemicals in leaf extract. The synthesized CuO nanoparticles were characterized by various analytical techniques such as UV–visible, X-ray diffraction, Fourier transform infra-red, dynamic light scattering, zeta potential and energy dispersive X-ray analyses. Field emission scanning electron micrographs and transmission electron micrographs illustrated the spherical and rectangular-rod shaped nanoparticles with its diameter (width) ranging from 20 to 40 nm. The antibacterial and biofilm activities against Gram-positive (Bacillus anthracis, and Listeria monocytogenes) and Gram-negative (Klebsiella pneumoniae) bacterial human pathogens showed strong inhibition at 95%, 94% and 92% in 150 μg/mL concentration, respectively. The antioxidant activity revealed high (97%) free radical scavenging property at 80 μg/mL concentration. The anti-inflammatory and anti-diabetic activities showed 90% and 85% efficacy at 500 μg/mL concentration, respectively. These results assured the synthesized CuO nanoparticles by using Capsicum frutescens leaf extract may have applications in the biomedical field.