Copper-doped carbon dot nanozymes for fluorescent detection of glutathione and broad-spectrum antibacterial applications

This study reports the development of multifunctional copper-doped carbon nanodots (CuCDNs) as an integrated nanozyme platform. Unlike previously reported systems, it show robust dua-enzyme mimetic activity, enabling excellent ROS regulation and antibacterial capabilities. CuCDNs demonstrate remarkable antibacterial effectiveness against Escherichia coli and Staphylococcus aureus at >100 μg/mL, which can be ascribed to synergistic mechanisms including the release of copper ions and enzym-mimetic activities. Furthermore, by utilizing copper–biothiol coordination, CuCDNs function as a highly sensitive and selective fluorescent probe for the detection of glutathione (GSH) via a static quenching mechanism, attaining a broad linear range of 0.1–220 μM and a detection limit of 0.0492 μM. Practical application in food samples yields recoveries of 88.03–103.2% (RSD < 4.4%). Cytotoxicity assays confirm excellent biocompatibility, maintaining over 85% in HMC3 cells at 1000 μg/mL. Their excellent cellular uptake and biocompatibility facilitated effective cellular imaging and discrimination of endogenous GSH levels between normal and cancer cells. In summary, as a multifunctional nanomaterial, it exhibits potential for advanced biosensing applications, antibacterial treatments, and within the realm of biomedical diagnostics.