Antibacterial and antibiofilm activity of green synthesized Mg-doped CeO2 nanoparticles using Actinidia deliciosa peel extract

Abstract

This study reports the green synthesis of cerium oxide (CeO₂) and magnesium-doped cerium oxide (Mg-doped CeO₂) nanoparticles by a sol–gel method using kiwi (Actinidia deliciosa) peel extract as a natural reducing and stabilizing agent. The synthesized nanoparticles were thoroughly characterized using a range of techniques including XRD, FTIR spectroscopy, FESEM, HRTEM, BET analysis, PL spectroscopy, Raman spectroscopy and UV-Vis spectroscopy. These analyses confirmed the successful synthesis of nanoparticles with well-defined crystalline structures and appropriate morphology. The antibacterial potential of the nanoparticles was evaluated against pathogenic bacteria including methicillin-resistant Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. Results demonstrated that both nanoparticles exhibited significant antibacterial activity, with Mg-doped CeO₂ nanoparticles showing the most potent antibacterial activity. The antibacterial activity of Mg-doped CeO₂ nanoparticles was evaluated by measuring the zone of inhibition, which was found to be 12 mm for Staphylococcus aureus, 15 mm for Escherichia coli, and 14 mm for Pseudomonas aeruginosa. Compared with the undoped CeO₂ nanoparticles, the Mg-doped CeO₂ nanoparticles exhibited enhanced antibacterial efficacy, with minimum inhibitory concentration (MIC) values of 62.5 µg mL⁻¹ for MRSA (S. aureus), 15.63 µg mL⁻¹ for E. coli, and 15.63 µg mL⁻¹ for P. aeruginosa. Furthermore, the synthesized Mg-doped CeO₂ nanoparticles demonstrated significant biofilm inhibition activity against methicillin-resistant Staphylococcus aureus (MRSA). The observed antibacterial activity was further supported by reactive oxygen species (ROS) generation, indicating ROS-mediated bactericidal action as the underlying mechanism. These findings highlight the potential of Mg-doped CeO₂ nanoparticles as effective antibacterial agents, offering a promising approach for the treatment of bacterial infections including those caused by antimicrobial-resistant strains.