Green synthesis of CeO2 and Zr/Sn-dual doped CeO2 nanoparticles with photoantioxidant and antibiofilm activities

Abstract

Cerium oxide (CeO₂) and 1%, 5% and 10% zirconium/tin-dual doped CeO₂ nanoparticles (Zr/Sn-dual doped CeO₂ NPs) were synthesized using an aqueous leaf extract of Pometia pinnata. By using UV-visible diffuse reflectance spectroscopy, the band gap energies of these materials were found to be in the range of ∼2.49 to 2.66 eV. The average crystallite sizes of the fluorite phase obtained from X-ray diffraction were between 7 and 16 nm. X-ray photoelectron spectroscopy (XPS) analysis further confirmed the synthesis of CeO₂ and Sn-doped CeO₂ NPs. Almost spherical shapes of the nanomaterials with an average particle size of 12–17 nm were determined using scanning electron microscopy and transmission electron microscopy studies. Photoantioxidant activities of the synthesized materials showed enhanced photoantioxidant response under visible light irradiation in comparison with those under dark conditions in both dose- and time-dependent manner. The CeO₂ NPs exhibited a significant concentration-dependent antibiofilm activity against the Gram-positive bacteria Staphylococcus aureus (S. aureus) and Listeria monocytogenes (L. monocytogenes). Only the 10% Zr/Sn-dual doped-CeO₂ NPs were found to inhibit S. aureus biofilm formation at higher concentrations. All Zr/Sn-dual doped CeO₂ NPs exhibited a concentration-dependent biofilm inhibition of L. monocytogenes and also bactericidal activity towards S. aureus. These nanomaterials exhibited enhanced photoantioxidant activities and antibacterial properties, which make them suitable for various biological applications.