A nanoprobe for nonprotein thiols based on assembling of QDs and 4-amino-2,2,6,6-tetramethylpiperidine oxide.

A new fluorescent nanoprobe, 4-amino-2,2,6,6-tetramethylpiperidine oxide (AT)-functionalized CdTe quantum dots (QDs-AT), was synthesized, for selective detection of nonprotein thiols based on electron transfer (ET). In the presence of nonprotein thiols, the nitroxide radicals in QDs-AT were converted to hydroxylamines, resulting in the fluorescence recovery of the quenched QDs. The detection mechanism of the probe was investigated using Rh-Se-2 probe. The nanoprobe has high sensitivity toward glutathione (GSH) with a detection limit of 7.1 × 10⁻⁸ M. The fluorescent imaging of living cells showed that QDs-AT could distinguish the concentration differences of GSH in HL-7702 and HepG2 cells.