Biosynthesis and characterization of copper oxide nanoparticles from Plumbago zeylanica leaf extract for antibacterial and antioxidant activities

Abstract

Abstract In recent years, green synthesis has become a prevalent method for producing metallic oxide nanoparticles, preferred over traditional physical and chemical processes because of its low toxicity, cost-effectiveness, and environmental friendliness. Therefore, this study aimed to synthesize and characterize CuO NPs using P. zeylanica leaf extract, as well as to assess their total phytochemical content, in vitro antibacterial properties, and antioxidant activity. The synthesized CuO NPs were analyzed using UV–visible spectrophotometry, XRD, SEM, FTIR, and TGA/DTA. UV–visible spectroscopy revealed SPR peaks at 376 nm, confirming the formation of CuONPs, with a band gap energy of 3.22 eV indicating their semiconductor nature. FTIR analysis reveals the presence of Cu–O bonds around 528cm−1. XRD analysis further confirmed the monoclinic phase of CuO NPs, with an average crystallite size of 25.15 nm. The spherical shapes of the synthesized CuO NPs were determined using SEM analysis. TGA/DTA analysis revealed a weight loss of 19.3% within the temperature range of 21–600 °C. Along with this study, the antibacterial activity of the biosynthesized CuONPs was evaluated using an agar well diffusion assay against three gram-negative and two gram-positive. The results demonstrate that CuO NPs were more effective against gram-negative bacteria, showing inhibition zones of 19.33 mm, 20.30 mm, and 16.50 mm against Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumonia, respectively. The antioxidant activity was evaluated, and IC50 values for DPPH assays of the synthesized CuO NPs, P. zeylanica leaf extract, and ascorbic acid were determined to be 123.77 ± 1.96, 97.28 ± 1.85, and 27.08 ± 0.15 μg/mL, respectively. These results indicate significant antioxidant and antibacterial activity for CuO NPs.