Synergistic Bacterial Stress Results from Exposure to Nano-Ag and Nano-TiO_2 Mixtures under Light in Environmental Media

摘要

Due to their widespread use and subsequent release, engineered nanomaterials (ENMs) will create complex mixtures and emergent systems in the natural environment where their chemical interactions may cause toxic stress to microorganisms. We previously showed that under dark conditions n-TiO_(2) attenuated bacterial stress caused by low concentrations of n-Ag ( Escherichia coli . We find increased production of hydrogen peroxide by the n-Ag-TiO_(2) mixture, revealing that the enhanced photocatalytic activity and production of ROS likely contribute to the stress response observed. Based on STEM-EDS evidence, we propose that a new composite Ag/TiO_(2) nanomaterial forms under these conditions and explains the synergistic effects of the ENM mixture. Overall, this work reveals that environmental transformations of ENM mixtures under irradiation can enhance biological stress beyond that of individual components.