Red emission nitrogen and zinc co-doped carbon dots as fluorescent sensor for reversible detection of peroxynitrite in living cells

Reactive oxygen species (ROS), including ONOO-, H2O2, ClO-, etc, are inevitable products of aerobic metabolism. They involved in physiological processes and have concentration-dependent influences. Furthermore, their intracellular contents are always in a state of flux. Since then, the reversible and dynamic monitoring of ROS is of great significance. Till now, only a few nano sensors could achieve reversible detection of ROS, and their fluorescence wavelengths are short. Herein, we developed N, Zn co-doped CDs (NZnCDs) with red fluorescence for selective and reversible detection of ONOO-. The NZnCDs possess catechol residues on their surface. The reversible transition of quinone/phenol and their different effect on fluorescence of the CDs lay the foundation of the redox reversible sensor. With emission wavelength of 619 nm and quantum yield of 0.21, NZnCDs can selectively respond to ONOO-, giving a good linearity in 2–40 μM, and can be efficiently recovered by GSH. Finally, the proposed rare redox reversible CDs have been successfully applied for the imaging of ONOO-/GSH in MCF-7 cells.