▎ 摘　　要

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 ARC 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 ARC transformation by GOs. Four GOs with different lateral sizes (10,060 0.17, and 0.08 mu m(2)) were prepared, and defined as GO(1.0), GO(0.60), GO(0.1)7 and GO(0.08). It is found that all the four GOs could effectively intercalate into plasmid DNA, and the intercalation abilities followed the order: GO(0.0)8> GO(0.17)> GO(0.60)> GO(1.0). 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 COs. For GO(0.08) at 25 pg/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 CO concentrations and smaller lateral sizes The inhibition of aphA transformation after G00.08 (25 nglinL) exposure achieved 50%. The size-dependent interaction of GOs with ARGscontaining plasmid DNA will be useful for guiding the environmental applications of GOs in reducing extracellular ARC transformation. (C) 2019 Elsevier B.V. All rights reserved.