State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai, 200092, China.
Department of Civil and Environmental Engineering, Rice University, Houston, TX, 77005, United States; Nanosystems Engineering Research Center for Nanotechnology Enabled Water Treatment (NEWT), United States.
Water Res. 2020 Oct 1;184:116157. doi: 10.1016/j.watres.2020.116157. Epub 2020 Jul 6.
There is growing pressure for wastewater treatment plants to mitigate the discharge of antibiotic resistant bacteria (ARB) and extracellular resistance genes (eARGs), which requires technological innovation. Here, hierarchical BiOCO microspheres were wrapped with nitrogen-doped, reduced graphene oxide (NRGO) for enhanced inactivation of multidrug-resistant E. coli NDM-1 and degradation of the plasmid-encoded ARG (bla) in secondary effluent. The NRGO shell enhanced reactive oxygen species (ROS) generation (•OH and HO) by about three-fold, which was ascribed to broadened light absorption region (red-shifted up to 459 nm) and decreased electron-transfer time (from 55.3 to 19.8 ns). Wrapping enhanced E. coli adsorption near photocatalytic sites to minimize ROS scavenging by background constituents, which contributed to the NRGO-wrapped microspheres significantly outperforming commercial TiO photocatalyst. ROS scavenger tests indicated that wrapping also changed the primary inactivation pathway, with photogenerated electron holes and surface-attached hydroxyl radicals becoming the predominant oxidizing species with wrapped microspheres, versus free ROS (e.g., •OH, HO and •O) for bare microspheres. Formation of resistance plasmid-composited microsphere complexes, primary due to the π-π stacking and hydrogen bonding between the shell and nucleotides, also minimized ROS scavenging and kept free plasmid concentrations below 10 copies/mL. As proof-of-concept, this work offers promising insight into the utilization of NRGO-wrapped microspheres for mitigating antibiotic resistance propagation in the environment.
污水处理厂面临着越来越大的压力，需要减轻抗生素耐药菌 (ARB) 和细胞外耐药基因 (eARGs) 的排放，这需要技术创新。在这里，分层 BiOCO 微球被氮掺杂还原氧化石墨烯 (NRGO) 包裹，以增强对多药耐药大肠杆菌 NDM-1 的灭活和二级出水中原位编码 ARG (bla) 的降解。NRGO 壳增强了活性氧物种 (ROS) 的生成 (•OH 和 HO)，约增加了三倍，这归因于拓宽的光吸收区域 (红移高达 459nm) 和减少的电子转移时间 (从 55.3 到 19.8 ns)。包裹增强了大肠杆菌在光催化位点附近的吸附，以最大限度地减少背景成分对 ROS 的清除，这使得 NRGO 包裹的微球的性能明显优于商业 TiO 光催化剂。ROS 清除剂测试表明，包裹还改变了主要的失活途径，与裸露微球的自由 ROS（例如•OH、HO 和•O）相比，包裹微球中的光生电子空穴和表面附着的羟基自由基成为主要的氧化物种。抗性质粒复合微球复合物的形成主要是由于壳层和核苷酸之间的π-π堆积和氢键作用，也最大限度地减少了 ROS 的清除，并将游离质粒浓度保持在 10 拷贝/ml 以下。作为概念验证，这项工作为利用 NRGO 包裹的微球来减轻环境中抗生素耐药性的传播提供了有希望的见解。
