Colorimetric and Fluorometric Assays for Dopamine with a Wide Concentration Range Based on Fe-MIL-88NH₂ Metal-organic Framework

Abstract

Metal-organic framework Fe-MIL-88NH₂ as a dual colorimetric and fluorometric sensor has been designed for a wide range of dopamine quantitative detection. It is easy to implement the assay for visual detection of dopamine based on restraining the color change of the 3,3′,5,5′-tetramethylbenzidine-H₂O₂ system that is catalyzed by Fe-MIL-88NH₂ with intrinsic peroxidase-like catalytic activity. The linear range is from 50 nM to 30 μM. In addition, the Fe-MIL-88NH₂ can exhibit a dramatic decrease of its fluorescent intensity when exposed to dopamine, which may be attributed to the electron transfer from the Fe-MIL-88NH₂ to the oxidized dopamine-quinone. The linear response range is from 30 μM to 4 mM. Meanwhile, both colorimetric and fluorometric methods exhibit higher selectivity for DA over a number of possible interfering substances. Furthermore, the proposed method has been successfully applied to detect DA in human serum samples, which suggests its great potential for analytical applications.