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Selective Adsorption and Photocatalytic Degradation of Extracellular Antibiotic Resistance Genes by Molecularly-Imprinted Graphitic Carbon Nitride

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journal contribution
posted on 17.03.2020, 17:03 by Qingbin Yuan, Danning Zhang, Pingfeng Yu, Ruonan Sun, Hassan Javed, Gang Wu, Pedro J. J. Alvarez
There is a growing need to mitigate the discharge of extracellular antibiotic resistance genes (ARGs) from municipal wastewater treatment systems. Here, molecularly-imprinted graphitic carbon nitride (MIP-C3N4) nanosheets were synthesized for selective photocatalytic degradation of a plasmid-encoded ARG (blaNDM‑1, coding for multidrug resistance New Delhi metallo-β-lactamase-1) in secondary effluent. Molecular imprinting with guanine enhanced ARG adsorption, which improved the utilization of photogenerated oxidizing species to degrade blaNDM‑1 rather than being scavenged by background nontarget constituents. Consequently, photocatalytic removal of blaNDM‑1 in secondary effluent with MIP-C3N4 (k = 0.111 ± 0.028 min–1) was 37 times faster than with bare graphitic carbon nitride (k = 0.003 ± 0.001 min–1) under UVA irradiation (365 nm, 3.64 × 10–6 Einstein/L·s). MIP-C3N4 can efficiently catalyze the fragmentation of blaNDM‑1, which decreased the potential for ARG repair by transformed bacteria. Molecular imprinting also changed the primary degradation pathway; electron holes (h+) were the predominant oxidizing species responsible for blaNDM‑1 removal with MIP-C3N4 versus free radicals (i.e., ·OH and O2) for coated but nonimprinted C3N4. Overall, MIP-C3N4 efficiently removed blaNDM‑1 from secondary effluent, demonstrating the potential for molecular imprinting to enhance the selectivity and efficacy of photocatalytic processes to mitigate dissemination of antibiotic resistance from sewage treatment systems.