Disulfide bond-based self-crosslinked carbon-dots for turn-on fluorescence imaging of GSH in living cells

Herein, we report a turn-on fluorimetric nanoprobe for intracellular glutathione (GSH) imaging. The principle of this probe is designed on the basis of the selective reduction between GSH and disulfide bond-based self-crosslinked red emissive carbon dots (abbreviated as SCCDs). The nanoprobe (i.e., SCCDs) was facilely fabricated from thiol-modified carbon dots (CDs) through oxidation in the presence of H2O2, and its fluorescence was greatly reduced due to the effect of aggregation induced quenching (AIQ). However, in the presence of GSH, the SCCDs were separated into many single CDs. As a result, the fluorescence of the nanoprobe was recovered in a GSH concentration-dependent manner, which is the basis for the quantitative analysis of GSH. The nanoprobe shows excellent specificity and a linear range from 0 to 0.15 mM towards GSH with a limit of detection (LOD) of 5.7 μM. Finally, the nanoprobe was demonstrated to have extremely low cytotoxicity, and was successfully applied for monitoring the GSH level in living cells. This work would provide a promising probe for the research of GSH in cytobiology.