Carbon quantum dot-AgOH colloid fluorescent probe for selective detection of biothiols based on the inner filter...

Here, we present a selective and sensitive fluorescent probe for the detection and distinction of biothiols, such as glutathione (GSH) and cysteine (Cys). The adsorbance of Cys onto the surface of AgOH colloid could result in enhanced absorbance from 250 to 400 nm in the UV-vis absorption spectrum, while the addition of GSH could dissolve the AgOH colloid resulting in no change in the UV-vis absorption spectrum. Utilizing these different phenomena, two fluorescent probes were established based on the inner filter effect (IFE). The first probe, the "CDs-AgOH colloid" fluorescent probe, was used to quantitatively analyze Cys over a linear concentration range from 33 to 317 μM and a detection limit of 7.2 μM. The second probe, the "CDs-AgOH colloid-Cys" fluorescent probe, was used to quantitatively analyze GSH, with a detection limit down to 3.6 μM, and a linear range of detection of approximately 16.7 to 100 μM. The fluorescent probes were successfully applied for the detection of GSH in a fetal bovine serum (FBS) sample. Based on these results, IFE is considered to be an effective way to distinguish GSH and Cys.