A self-calibrating fluorescence / colorimetric dual-mode sensor based on MIL-101(Fe) for specifical dopamine detection in human serum

Dopamine (DA) is an essential biomarker implicated in the diagnosis of neurological diseases. In this work, we designed a dual-enzyme mimetic activity MIL-101(Fe) that catalyzed specific cyclization reaction between 1,3-dihydroxynaphthalene (NR) and dopamine. As the concentration of dopamine increased, the fluorescence emission of NR at 440 nm was markedly quenched, concomitant with the emergence of a new fluorophore exhibiting enhanced emission at 480 nm and increased absorbance at 462 nm. The ratiometric fluorescence/colorimetric dual-mode detection strategy provided intrinsic self-calibration to effectively mitigate signal variations. Furthermore, a linear correlation was established for ratiometric fluorescence signal across the range of 0.25–35 μM (R 2  = 0.999), and similarly for colorimetric absorbance (R 2  = 0.999). This method provided an accurate, specific, sensitive and high-throughput detection of dopamine in human serum.