Exploring the optical and biological aspects of sodium- doped CuO nanoparticles

Abstract

In this article, we present a novel coprecipitation technique for synthesizing pure and sodium-doped CuO (Cu1-xNaxO) nano powders with different sodium concentrations (x = 0, 0.01, 0.02, 0.04, 0.06, 0.08, and 0.10). The structural properties of the samples were analysed using powder X-ray diffraction (PXRD), which revealed an average crystallite size of 12.48–10.50 nm. The bonding nature of the Cu1-xNaxO samples was described by Fourier transform infrared (FTIR) spectroscopy. The UV–Visible spectroscopic analysis showed a band gap energy of 1.240–1.456 eV and a refractive index that decreased with an increase in Na doping concentration. Field emission scanning electron microscopy images revealed the spherical, flower-shaped, and flake-like morphologies of the nanoparticles, which had sizes ranging from 42.45 ± 5.49–33.98 ± 4.32 nm. Energy-dispersive X-ray spectroscopy and elemental mapping were used to confirm the purity of the samples and the presence of Cu, O, and Na elements in the Cu1-xNaxO samples. High-resolution transmission electron microscopy photomicrographs confirmed that the samples were polycrystalline and the nanoparticles exhibited nucleation with lattice spacing, as shown by selected-area electron diffraction patterns. Furthermore, the Cu1-xNaxO nano powders exhibited efficient antibacterial and antifungal activities. The antibacterial activity was tested against major bacterial strains, and the highest inhibition zones were observed to be 13.67 ± 1.11 mm (x = 0.06), 10.67 ± 0.94 mm (x = 0.10), 15 ± 1.11 mm (x = 0.10), and 9.25 ± 0.25 mm (x = 0.06) for P. aeruginosa, B. subtilis, S. aureus, and K. pneumonia, respectively. In addition, the antifungal activity of the Na-doped CuO nano powders was found to be enhanced against polymorphic fungus C. albicans and filamentous fungus A. niger with dopant concentration. These results suggest that Na-doped CuO NPs have potential applications in formulating new antifungal drugs and treating various life-threatening bacterial infections.