Photoantioxidant and antibiofilm studies of green synthesized Sn-doped CeO2 nanoparticles using aqueous leaf extracts of Pometia pinnata

Abstract

Cerium oxide (CeO₂) and 1%, 5% and 10% tin-doped CeO₂ nanoparticles (Sn-doped CeO₂ NPs) were synthesized using aqueous leaf extracts of Pometia pinnata. UV-Vis diffuse reflectance spectroscopy showed band gap energies of 2.47–2.66 eV. X-ray diffraction results confirmed the formation of a fluorite phase of CeO₂ and Sn-doped CeO₂ NPs with average crystallite sizes between 6 and 19 nm. X-ray photoelectron spectroscopy (XPS) analysis further established the synthesis of CeO₂ and Sn-doped CeO₂ NPs. The density of states was proposed accordingly using the valence band-XPS data. Scanning electron microscopic and transmission electron microscopic studies showed almost spherical shaped particles with average particle sizes around 15–20 nm. All synthesized nanomaterials were tested for photoantioxidant activity under visible light and in the dark and showed improved photoantioxidant activity under visible light irradiation for dose and time-dependent studies. The synthesized nanomaterials were also tested for antibiofilm activities and exhibited significant concentration-dependent antibiofilm activity against Gram-positive pathogenic bacteria such as Staphylococcus aureus and Listeria monocytogenes. The 10% Sn-doped CeO₂ NPs and S-CeO₂ NPs also exhibited bactericidal activity against Staphylococcus aureus. These studies showed that S-CeO₂ and Sn-doped CeO₂ NPs have both good antioxidant and antibacterial properties.