Highly sensitive fluorescent detection of glutathione and histidine based on the Cu(II)-thiamine system

In this work, we propose a fluorescence method for the simultaneous detection of glutathione (GSH) and histidine (His) based on the Cu(II)-thiamine (Cu(II)-TH) system. It is well established that non-fluorescent thiamine (TH) can be oxidized by Cu(II) to generate fluorescent thiochrome (TC) under alkaline conditions. The introduction of GSH and His can inhibit the oxidation of TH by Cu(II) due to the strong affinity between Cu(II) and GSH or His. With this strategy, the detection limit for GSH and His is 10.5 nM and 26.4 nM, respectively. The developed method shows several obvious advantages: (1) simplicity in design and operation without the utilization of fluorescent nanomaterials or probes; (2) time-saving detection process since all the detection process is completed within 15 min; (3) cost-effectiveness by using TH as the fluorescent substrate; and (4) higher sensitivity and good selectivity. Therefore, it shows great potential in biosensing fields.