Turn-on fluorescent probe for dopamine detection in solutions and live cells based on in situ formation of aminosilane-functionalized carbon dots.

Dopamine (DA) is a critical biomarker for a variety of neurological diseases. Methods for simple and rapid DA detection are crucial for clinical diagnosis and treatments for those diseases. In this work, we developed a novel pretreatment-free method for dopamine detection using carbon dots as a turn-on fluorescent probe synthesized in situ. The aminosilane-functionalized carbon dots (SiCDs) were produced in a mild condensation reaction between N-[3-(Trimethoxysilyl)propyl]ethylenediamine (AEATMS) and dopamine, which were directly used for probing of dopamine. The prepared SiCDs exhibited green fluorescence with excitation/emission maximum at 380/495 nm, the intensity of which can be measured to quantify the DA present in the reaction mixture. The linear range of the assay was between 0.1 and 100 μM with a limit of detection (LOD) of 56.2 nM. The probe is of good selectivity and the recoveries of the developed method were in the range of 101.77-119.91% with RSDs within 3.67% in human serum sample tests. The SiCDs were also synthesized within MN9D cells under 37 °C and generated bright fluorescence, which can probe the DA's distribution in the cells. The described method exhibit potential in DA detection and live-cell imaging for its feature of facility, inexpensiveness, and sensitivity.