Fluorescent Determination of Mercury (II) and Glutathione Using Amino-MIL-53(Al) Nanosheets

Amino-MIL-53(Al) nanosheets were synthesized by a hydrothermal reaction and were employed as a fluorescent probe because of their high quantum yield and excellent stability. The amino-MIL-53(Al) nanosheets have a maximum fluorescence emission peak at 435 nm using an excitation wavelength of 335 nm. The fluorescent intensity of luminophor at 435 nm was linearly quenched when mercury (II) (Hg2+) was added, which occurred due to the adsorption of Hg2+ onto the luminophor surface. Under these conditions, the fluorescent signal of the system is in the “turn-off” state. Following the addition of glutathione (GSH) into the system, the quenched fluorescence intensity may be partially restored based on the reaction between glutathione and Hg2+. In this condition, the fluorescent signal of the amino-MIL-53(Al)-Hg2+ system is in the “turn-on” state. Therefore, the amino-MIL-53(Al) nanosheets were successfully used as a “turn-off-on” fluorescent sensing system to determine the concentrations of Hg2+ in Tibetan medicine and glutathione in rabbit serum. A good correlation coefficient was obtained between the quenching of the fluorescence intensity of luminophor and the concentration of Hg2+ using the optimized conditions. A linear range was acquired from 1.96 nM to 38.27 μM with a detection limit of 0.23 nM of Hg2+ based upon a signal-to-noise ratio of three. For glutathione, the linear dynamic range was from 210 nM to 15.25 μM with a detection limit equal to 8.11 nM based upon a signal-to-noise ratio of three. This developed sensor system has the advantages of high selectivity, favorable sensitivity and simple operation for the determination of Hg2+ and glutathione in real samples.