Carbon dots-based ratiometric nanosensor for highly sensitive and selective detection of mercury(ii) ions and glutathione

Abstract

Glutathione (GSH) plays a crucial role in many cellular processes. Recently, great efforts have been made to develop efficient methods for GSH sensing in organisms. Herein, we reported the design and application of a specific ratiometric fluorescent probe, which contained carbon quantum dots (CDs) as sensing signal and Rhodamine B (RhB) as reference, for highly sensitive detection of mercury ions (Hg²⁺) and glutathione (GSH). The obtained nanosensor showed characteristic fluorescence emissions of CDs and RhB under a single excitation wavelength. The functional CDs were first synthesized in our laboratory according to a one-pot pyrolysis process of sodium citrate with histidine. In the presence of Hg²⁺, only the fluorescence of CDs was quenched due to electron transfer between Hg²⁺ and functional groups on the surface of CDs. Subsequently, the fluorescence of CDs–Hg²⁺ system was recovered gradually with the addition of GSH due to their stronger affinity with Hg²⁺, which could effectively exclude numerous background interferences. This method has been successfully applied to oxidative stress model investigation. The proposed ratiometric sensing strategy was proven to be facile, reliable, sensitive and selective, showing great potential for Hg²⁺ and GSH detection in environmental monitoring and biological detection.