Cytotoxicity of CeO₂ Nanoparticles for Escherichia coli. Physico-Chemical Insight of the Cytotoxicity Mechanism

Abstract

The production of nanoparticles (NPs) is increasing rapidly for applications in electronics, chemistry, and biology. This interest is due to the very small size of NPs which provides them with many interesting properties such as rapid diffusion, high specific surface areas, reactivity in liquid or gas phase, and a size close to biomacromolecules. In turn, these extreme abilities might be a problem when considering a potentially uncontrolled exposure to the environment. For instance, nanoparticles might be highly mobile and rapidly transported in the environment or inside the body through a water or air pathway. Accordingly, the very fast development of these new synthetic nanomaterials raises questions about their impact on the environment and human health. We have studied the impact of a model water dispersion of nanoparticles (7 nm CeO2 oxide) on a Gram-negative bacteria (Escherichia coli). The nanoparticles are positively charged at neutral pH and thus display a strong electrostatic attraction toward bacterial outer membranes. The counting of colony forming units (CFU) after direct contact with CeO2 NPs allows for the defining of the conditions for which the contact is lethal to Escherichia coli. Furthermore, a set of experiments including sorption isotherms, TEM microscopy, and X-ray absorption spectroscopy (XAS) at cerium L3 edge is linked to propose a scenario for the observed toxic contact.

Heteroaggregation of nanoparticles with biocolloids and geocolloids

“…Heteroaggregation of NPs with microbial cells such as bacteria and algae is important for fate, transport, transformation, and toxicity of NPs in both aquatic and terrestrial environments [106][107][108][109][110][111][112][113]. Heteroaggregation could occur between a single particle and a cell, or via particle aggregate-cell interactions [114] -with important implications in the natural environment.…”

“…For instance, NPs-microorganism heteroaggregation can lead to increased removal of NPs from wastewater during secondary treatment [106,[115][116][117][118]. Interactions between cell walls of microorganisms and NPs are also thought to precede uptake and toxicity [107,108,[110][111][112]116,119], and may be important for trophic transfer of NPs in both aquatic and terrestrial environments [108,[119][120][121].…”

Antibiofilm activity of biogenic copper and zinc oxide nanoparticles-antimicrobials collegiate against multiple drug resistant bacteria: a nanoscale approach

“…Studies on antibacterial activity among the various metal oxides nanoparticles, zinc oxide nanoparticles, have been found to be highly toxic. Many studies have shown that selective toxic nature of ZnONPs toward bacteria shows the minimal effect on human cells, which is suggested their potential uses in agricultural, food industries, diagnostics, surgical devices, and nanomedicine-based antimicrobial agents [21][22][23][24]. Among the several metal oxide nanoparticles, ZnONPs are emerged as booming nanoparticle due to their attractive characteristics and ideal properties in various biomedical applications.…”

Eco-friendly drugs from the marine environment: spongeweed-synthesized silver nanoparticles are highly effective on Plasmodium falciparum and its vector Anopheles stephensi, with little non-target effects on predatory copepods

“…The exact mechanisms of nanoparticle toxicity against various bacteria are not understood completely. Nanoparticles are able to attach to the membrane of bacteria by electrostatic interaction, and disrupt the integrity of the bacterial membrane (Thill et al 2006). Nanotoxicity is generally triggered by the induction of oxidative stress by free radical formation (Nel et al 2009;Soenen et al 2011).…”