Metal-modified WO3: Photocatalytic removal of extracellular antibiotic resistance genes and mitigation of transformation-mediated horizontal gene transfer potential

Cu-WO 3 efficiently removed extracellular plasmid pBR322 under visible light. • Representative DNA structural units were further oxidized by Cu-WO 3 . • Cu-WO 3 reduced pBR322 transformation frequency by 96.9% within 20 min. • Cu modification promoted charge separation and reactive species generation. • h + - and ·O 2 − -associated pathways showed the strongest involvement in DNA oxidation. The spread of antibiotic resistance genes (ARGs) through horizontal gene transfer (HGT) poses an important environmental and public health concern. In this study, Ag-, La-, and Cu-modified WO 3 were compared for photocatalytic removal of the model extracellular ARG-carrying plasmid pBR322 , and the residual transformation potential after treatment was further evaluated. Cu-WO 3 showed the highest photocatalytic activity among the tested materials. 97.4% of plasmid pBR322 was removed in 20 min under visible light, with a rate constant 66.7% higher than that of pristine WO 3 . Four representative deoxyribonucleosides were almost completely degraded within 40 min, demonstrating the oxidative susceptibility of DNA structural units. The transformation frequency of pBR322 decreased by 96.9% after 20 min, indicating a substantial reduction in residual transformation potential. Cu modification enhanced photogenerated charge separation, interfacial charge transfer, and reactive-species generation, with pathways associated with h + and ·O 2 − showing the strongest apparent involvement in DNA oxidation. Cu-WO 3 also progressively disrupted plasmid structure and partially mineralized nitrogen-containing components. These results indicate the potential of Cu-modified WO 3 for photocatalytic control of extracellular ARG-carrying DNA and mitigation of transformation-mediated HGT potential.