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

摘要

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-C_3N_4) nanosheets were synthesized for selective photocatalytic degradation of a plasmid-encoded ARG (bla_(NDM-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 bla_(NDM-1), rather than being scavenged by background nontarget constituents. Consequently, photocatalytic removal of bla_(NDM-1) in secondary effluent with MIP-C_3N_4 (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-C_3N_4 can efficiently catalyze the fragmentation of bla_(NDM-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 bla_(NDM-1) removal with MIP-C_3N_4 versus free radicals (i.e., ·OH and O_2~-) for coated but nonimprinted C_3N_4. Overall, MIP-C_3N_4 efficiently removed bla_(NDM-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.