Biosynthesis of copper, cobalt, and zinc oxide nanoparticles using the seed extract of Citrullus lanatus and determination of biological potentials

Abstract

The research is based on using a greener approach for synthesizing cobalt oxide, copper oxide, and zinc oxide nanoparticles using the seed extract of Citrullus lanatus (CL). The synthesized nanoparticles were characterized by UV-vis, FT-IR spectroscopy, XRD, SEM, and EDX analysis. Scanning electron microscopy (SEM) analysis revealed that the particles are uniformly distributed with average sizes of 146.49 ± 45.15, 176.37 ± 50.47, and 123.61 ± 27.26 nm for Co₃O₄, CuO, and ZnO nanoparticles, respectively. The crystalline nature of the nanoparticles was confirmed by X-ray diffraction (XRD), which revealed average particle sizes of 12.38, 10.46, and 11.76 nm for Co₃O₄, CuO, and ZnO nanoparticles, respectively. The specific surface area (SSA) was calculated to be 79.84, 90.90, and 90.94 m² g⁻¹ for Co₃O₄, CuO, and ZnO, respectively. A maximum inhibition diameter of 15 mm was exhibited by CuO and ZnO against S. aureus and B. subtilis. ZnO nanoparticles exhibited 90% and 81% activity in the DPPH and total phenolic content assays, respectively. Maximum α-amylase and protease inhibition activities were demonstrated by the Co₃O₄ and ZnO nanoparticles, with values of about 62% and 71%, respectively.