Nitrogen-doped graphene quantum dots-MoS2 nanoflowers as a fluorescence sensor with an off/on switch for intracellular glutathione detection and fabrication of molecular logic gates

We designed and evaluated a high-performing and biocompatible sensing platform to quantitatively detect glutathione (GSH) in the intracellular environment. To this end, we constructed a fluorescent switch using nitrogen-doped graphene quantum dots (N-GQDs) as fluorescent probes and MoS 2 nanoflowers as the GSH recognition unit. Fluorescence emission of N-GQDs was first switched OFF when combined with MoS 2 nanoflowers due to the fluorescence resonance energy transfer (FRET) mechanism. It was readily switched ON by reducing MoS 2 to Mo 3+ in the presence of GSH, enabling the recovery of fluorescent signal. We performed experiments to test the dependence of the sensing platform fluorescence intensity on the concentrations of GSH in the range of 0.4–4.4 mM. The detection limit was 2.47 μM. The monitoring of concentrations of GSH in human retinal pigment epithelium cells (ARPE-19) samples revealed excellent sensing performance with facilitated visualization of the probe, suggesting that the unique sensing strategy has the exceptional anti-interference property for assessing the intracellular GSH quantity in diagnostics and biomedical research. The OFF/ON switch for the detection of GSH was explored to create a XNOR molecular logic gate.