Insights into the antibacterial mechanism of iron doped carbon dots

Antibacterial nanomaterials provide promising alternative strategies to combat the bacterial infection due to deteriorating resistance. However, few have been practically applied due to the lack of clear antibacterial mechanisms. In this work, we selected good-biocompatibility iron-doped CDs (Fe-CDs) with antibacterial activity as a comprehensive research model to systematically reveal the intrinsic antibacterial mechanism. Through energy dispersive spectroscopy (EDS) mapping of in situ ultrathin sections of bacteria, we found that a large amount of iron was accumulated inside the bacteria treated with Fe-CDs. Then, combining the data of cell level and transcriptomics, it can be elucidated that Fe-CDs could interact with cell membranes, enter bacterial cells through iron transport and infiltration, increase intracellular iron levels, trigger increased reactive oxygen species (ROS), and lead to disruption of Glutathione (GSH)-dependent antioxidant mechanisms. Excessive ROS further leads to lipid peroxidation and DNA damage in cells, lipid peroxidation destroys the integrity of the cell membrane, and finally leads to the leakage of intracellular substances resulting in bacterial growth inhibition and death. This result provides important insights into the antibacterial mechanism of Fe-CDs and further provides a basis for the deep application of nanomaterials in biomedicine.