Cleavage and transformation inhibition of extracellular antibiotic resistance genes by graphene oxides with different lateral sizes

Abstract

Due to excessive consumption of antibiotics, antibiotic resistance genes (ARGs) become a ubiquitous pollutant in aquatic environments. Graphene oxide (GO), an emerging 2D nanomaterial, was used for potential control of ARG contamination in the present work. We systematically investigated the interaction of GOs with Kanamycin resistance gene (aphA)-containing plasmid DNA, and related the inhibition of ARG transformation by GOs. Four GOs with different lateral sizes (1.0, 0.60, 0.17, and 0.08 μm2) were prepared, and defined as GO1.0, GO0.60, GO0.17 and GO0.08. It is found that all the four GOs could effectively intercalate into plasmid DNA, and the intercalation abilities followed the order: GO0.08 > GO0.17 > GO0.60 > GO1.0. Based on circular dichroism (CD) spectrum analysis, all GOs disturbed the base stacking mode and double helix structure of DNA, which is positively related to the intercalation activities of GOs. For GO0.08 at 25 μg/mL, the supercoiled plasmid DNA was partially cleaved, and the nicked and linear structures were observed based on agarose gel electrophoresis analysis. Moreover, the amplification and transformation of aphA gene were both inhibited due to GO-plasmid DNA interactions, and the inhibition was stronger with increasing GO concentrations and smaller lateral sizes. The inhibition of aphA transformation after GO0.08 (25 μg/mL) exposure achieved 50%. The size-dependent interaction of GOs with ARGs-containing plasmid DNA will be useful for guiding the environmental applications of GOs in reducing extracellular ARG transformation.