Influence of Commercial ZnO Particle Size on the Inactivation of Escherichia coli DH5α

Abstract Contamination of water bodies by pathogenic organisms, especially those modified or with antibiotic resistance, constitutes a significant risk to environmental and human health. In this context, the present study focused on comparing the antimicrobial activity of commercial ZnO powders (ZnO − 5 μm, ZnO < 5 μm, and ZnO − 100 nm) as a sustainable alternative for the elimination of these microorganisms. Structural results, obtained by XRD and Raman, confirmed that all three samples exhibit a hexagonal wurtzite structure. Likewise, a similarity in the band gap (Eg) value was observed, with minimal variations that could be associated with the synthesis method. SEM images revealed the presence of agglomerates formed by primary particles. This phenomenon was corroborated through DLS, reporting an increase of up to 10 times in the hydrodynamic size in solution. Regarding colloidal stability, the ZnO − 5 sample showed slightly higher stability compared to ZnO < 5 and ZnO − 100 nm, which proved to be more unstable. Finally, the release of Zn 2+ ions was quantified, with ZnO − 5 being the sample that exhibited the highest ionic concentration. This factor correlated directly with efficacy, as ZnO − 5 was the treatment that showed the highest performance in the elimination of the Escherichia coli DH5α strain, achieving inhibition in four out of the five concentrations used compared to the other powders.