Comparison of Microbial Interactions of Zinc Oxide Nanomaterials in Various Size and Shape

Abstract

Zinc oxide nanoparticles (ZnO NP) have shown great potential as a novel antibacterial material at a time when resistance towards conventional antibiotics is becoming more prevalent. We report bacteria inactivation by ZnO NP with novel hedgehog-like morphology using model gram-negative (E. coli) and gram-positive (S. aureus) bacteria. E. coli exposed to the novel ZnO hedgehog NP during growth resulted in 4 orders of magnitude reduction in viable cell concentration after 24 h, which is more than 2 orders higher reduction compared to commercially available ZnO NPs with nominal sizes from 50 nm to 20 um. There was a positive correlation between hedgehog NP concentration and bacteria cell concentration reduction within the range tested 0.1 -1.0 mg/mL. S. aureus was less sensitive to ZnO NP exposure and inactivation effect of various ZnO NP, was comparable. The effect can be thus attributed to direct mechanical damage of the bacterial mebrane that is the most effective for the novel hedgehog ZnO NP. This conclusion was corroborated also by disk diffusion assays.

Growth Inhibition of Gram-Positive and Gram-Negative Bacteria by Zinc Oxide Hedgehog Particles

“…3 Based on these prior findings, one can assume that particle shape and size may have a certain positive influence on the antibacterial effect of ZnO, however, this effect is not completely understood due to the complexity of such studies and variety of ZnO materials employed. Our prior studies have hinted at particle shape and size dependency on the antibacterial effect of ZnO in microbial growth broth with standard unidirectional orbital rotation shaker 19 and a concentration dependency for nanosized ZnO in water with bidirectional reverse spin rotation mixing. 20 In this study, we thus aim to elucidate the influence of ZnO particle shape, size and concentration on the ability to inhibit growth of bacteria in a range of different environments using synthesized needle-like ZnO structures and commercial ZnO particles, without using illumination.…”