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.