Colorimetric determination of thiol compounds in serum based on Fe-MIL-88NH2 metal–organic framework as peroxidase mimetics

Abstract

Herein, a novel and simple colorimetric method for the detection of thiol compounds was established based on iron-containing metal–organic framework Fe-MIL-88NH₂ as peroxidase mimetics. Fe-MIL-88NH₂ could catalyze the oxidation of the peroxidase substrate 3,3′,5,5′-tetramethylbenzidine (TMB) by H₂O₂ to develop a blue color in aqueous solution. However, when thiol compounds, such as glutathione (GSH), cysteine (Cys) or homocysteine (Hcy), coexisted in the solution, the color of the responsive solution gradually became pale due to the competitive reaction between TMB and thiol compounds with H₂O₂. Therefore, the content of thiol compounds could be calculated according to the change of absorbance in the system. Under optimum experimental conditions, linear response ranges for GSH, Hcy and Cys were 1.0–100.0 μM, 1.0–80.0 μM and 1.0–80.0 μM, and the detection limits were 0.45 μM, 0.40 μM and 0.39 μM, respectively. Furthermore, the colorimetric method was successfully applied to the detection of total thiol compounds in serum.