AbstractAntibiotic resistance is a severe problem worldwide. To address this issue, nanomaterials are applied to combat bacteria. On account of their high biocompatibility, easy surface modifications, and admirable optical properties, quantum dots are widely researched. Here, l‐type cysteine (l‐Cys)‐decorated cadmium telluride (CdTe) nanoparticles (NPs) as an agent to combat bacteria based on their photoinduced oxidation feature are reported. Interestingly, l‐Cys CdTe mixed with salmon sperm DNA and then illuminated by right circularly polarized light (RCP) will lead to reaction oxygen species (ROS) production. To achieve a high local concentration of ROS around the membrane and selective adherence to gram‐negative bacteria (Escherichia coli and Pseudomonas aeruginosa in this study), l‐Cys CdTe is decorated with a polycationic nonapeptide (PCNP‐l‐Cys CdTe). Upon irradiation, the bacterial membrane is severely damaged by the resulting high local ROS concentration. In addition, PCNP‐l‐Cys CdTe, which has intrinsic fluorescence characteristics, shows outstanding fluorescence imaging ability in vivo. It is successfully applied to the fluorescence imaging‐guided bacterial infection therapy.
