Antimicrobial Activity of Cerium Oxide Nanoparticles on Opportunistic Microorganisms: A Systematic Review

Abstract

An evaluation of studies of biologically active nanoparticles provides guidance for the synthesis of nanoparticles with the goal of developing new antibiotics/antifungals to combat microbial resistance. This review article focuses on the physicochemical properties of cerium oxide nanoparticles (CeNPs) with antimicrobial activity. Method. This systematic review followed the Guidelines for Transparent Reporting of Systematic Reviews and Meta-Analyses. Results. Studies have confirmed the antimicrobial activity of CeNPs (synthesized by different routes) using nitrate or chloride salt precursors and having sizes less than 54 nm. Conclusion. Due to the lack of standardization in studies with respect to the bacteria and CeNP concentrations assayed, comparisons between studies to determine more effective routes of synthesis are difficult. The mechanism of CeNP action likely occurs through oxidative stress of components in the cell membrane of the microorganism. During this process, a valence change occurs on the CeNP surface in which an electron is gained and Ce⁴⁺ is converted to Ce³⁺.

Figure 1

Flow diagram of the search strategy used to identify studies included in this review based on PRISMA guidelines [19].

Figure 2

Diagram of the probable mechanism of antimicrobial action for cerium oxide nanoparticulates on the cell membrane. Candida albicans; (b) the cell wall of the fungus formed by monoproteins, insoluble glycan and chitin. Phospholipid bilayer of the cell membrane with glycan synthase and ergosterol. (c) Adsorption of cerium oxide nanoparticles, reduction of Ce⁴⁺ to Ce³⁺, elevation of pH, and oxidative stress of the fungus.