Fluorescence and colorimetric dual-signal determination of Fe3+ and glutathione with MoSe2@Fe nanozyme

In this paper, MoSe2@Fe nanozyme with excellent enzymatic properties and fluorescence properties were synthesized by a facile one-pot hydrothermal method, and an efficient and reliable on-off-on colorimetric and off-on-off fluorescent dual-signal chemical sensor was developed for the sensitive and selective determination of Fe3+ and GSH in food samples. The Fenton reaction between Fe3+ and nanozyme can catalyze the decomposition of H2O2 to produce ·OH radicals, which oxidized colorless 3,3′,5,5′-tetramethylbenzidine (TMB) to blue oxidized TMB (ox-TMB). Due to the reaction of GSH and ox-TMB, it can be directly observed with naked eyes that the blue color of the solution became lighter. In addition, the fluorescence of MoSe2@Fe was quenched by Fe3+, but the added GSH reacted with Fe3+ so that the quenched fluorescence was recovered. Thus, the standard curves of detection of Fe3+ and GSH through fluorescence-colorimetric method were established in the range of 25–300 μM and 5–80 μM (Fe3+), 1.67–13.3 μM and 1.67–33.3 μM (GSH), and the detection limits were 1.97 μM and 0.65 μM (Fe3+), 0.93 μM and 3.07 μM (GSH), respectively. The developed dual-signal (on-off-on colorimetric and off-on-off fluorescent) sensor has been applied successfully to detect Fe3+ and GSH in the food samples.