Toxicity of Graphene and Graphene Oxide Nanowalls Against Bacteria

Abstract

Bacterial toxicity of graphene nanosheets in the form of graphene nanowalls deposited on stainless steel substrates was investigated for both gram-positive and gram-negative models of bacteria. The graphene oxide nanowalls were obtained by electrophoretic deposition of Mg(2+)-graphene oxide nanosheets synthesized by a chemical exfoliation method. On the basis of measuring the efflux of cytoplasmic materials of the bacteria, it was found that the cell membrane damage of the bacteria caused by direct contact of the bacteria with the extremely sharp edges of the nanowalls was the effective mechanism in the bacterial inactivation. In this regard, the gram-negative Escherichia coli bacteria with an outer membrane were more resistant to the cell membrane damage caused by the nanowalls than the gram-positive Staphylococcus aureus lacking the outer membrane. Moreover, the graphene oxide nanowalls reduced by hydrazine were more toxic to the bacteria than the unreduced graphene oxide nanowalls. The better antibacterial activity of the reduced nanowalls was assigned to the better charge transfer between the bacteria and the more sharpened edges of the reduced nanowalls, during the contact interaction.

Fe3+-saturated montmorillonite effectively deactivates bacteria in wastewater

“…In general, bacterial deactivation can be the result of: 1) direct mechanical breakage of outer cell membranes by sharp edged nanoparticles (Akhavan and Ghaderi, 2010;Liu et al, 2009;Situ and Samia, 2014); 2) chemical oxidative stress mediated cell injury that is induced by in situ production of reactive oxygen species (Krishnamoorthy et al, 2012;Su et al, 2009); and 3) dehydration of cell membrane (Beney et al, 2004). It is highly likely that the latter two bacterial deactivation mechanisms are at play when wastewater is exposed to Fe 3+ -saturated montmorillonite.…”

Environmental applications using graphene composites: water remediation and gas adsorption

“…133,232 Akhavan et al showed that the bacterial inactivation was caused by direct contact of the bacteria with the extremely sharp edges of the nanosheets which results in cell membrane damage. This mechanism of bacterial inactivation therefore allows E. coli to be more resistant to graphene materials compared to S. aureus, due to its outer cell membrane.…”

Nanotechnology in agriculture, livestock, and aquaculture in China. A review

“…The toxicity of nanotechnologies on microbial is mainly exhibited in growth inhibition, inhibition of cell wall formation, or cell morphological damage, which thus exert an influence on the microbial community. Graphene and grapheme oxide may both lead to cell membrane damage ruptures of gram-negative bacteria (E. coli) and gram-positive bacteria (S. aureus), resulting in leakage of intracellular substances and thus cell death (Akhavan and Ghaderi 2010). Nano TiO 2 and nano ZnO also affect the soil microbial community, reduce the quantity and diversity of microorganisms in soil, and change soil microbial community compositions (Ge et al 2011).…”