Antimicrobial activity enhancement of MgO nanoparticles through Zn doping against multidrug-resistant bacteria

• Increasing Zn doping on MgO lattice, increases crystallite size and particle size. • A reduction of the bandgap to 4.7 eV, enhances potential reactivity in Zn-doped MgO. • Raman signals corroborates the presence of -OH and CO3 species bonded to MgO surface. • Increasing Zn doping on MgO lattice promotes reactive oxygen species production. • Zn-doping enhances MgO antimicrobial action via ROS from surface hydroxylation. The structural, morphological, and antibacterial effects resulted from incorporating zinc into magnesium oxide (MgO) host lattice. Two samples were synthesized via the precipitation method with 10 and 16% zinc concentrations, and their properties were compared with those of a commercial (MgOc) sample. Structural analyses confirmed a cubic structure with space group Fm-3 m, which underwent distortions as Zn concentration increased. Microstructural studies via X-ray diffraction and transmission electron microscopy revealed nanoparticle (NPs) formation with a polyhedral morphology resulting from surface hydroxylation of cubic-shaped particles. Zinc incorporation and the presence of defects centers such as oxygen vacancies creates electronic states inside the bandgap reducing the bandgap energy value from 5.7 eV to 4.7 eV. Furthermore, an increase in Urbach energy was observed, suggesting greater energetic disorder due to the introduction of localized electronic levels within the bandgap. Zinc incorporation also increasing the average particle size. Antibacterial activity was evaluated based on IC 50 . For Staphylococcus aureus ATCC, IC 50 values were 0.8 mg/mL and 0.49 mg/mL for commercial MgO NPs (MgOc) and MgO-Zn 10, respectively. In the case of S. aureus , multidrug-resistant (MDR) needed 2.81 mg/mL MgOc NPs, whereas IC 50 was reduced to 0.69 mg/mL for MgO-Zn 10. For Pseudomonas aeruginosa ATCC, IC 50 of MgOc NPs was 0.77 mg/mL, whereas a decrease of 0.34 mg/mL was observed for MgO-Zn 10. Concerning P. aeruginosa MDR, IC 50 of MgOc NPs was 0.710 mg/mL, whereas a value lower than 0.5 mg/mL was recorded for MgO-Zn 10. These results suggest that using MgO‒Zn nanoparticles represents a promising strategy for combating multidrug-resistant bacteria.