A simple and sensitive fluorometric dopamine assay based on silica-coated CdTe quantum dots

A fluorescence assay is described for the fluorometric determination of dopamine (DA). It based on the use of silica-coated CdTe quantum dots (QD@SiO 2 ). These were fabricated through a hydrothermal process. When DA is added to a solution of the QD@SiO 2 and then oxidized by oxygen under catalytic action of tyrosinase to form dopamine quinone, the fluorescence of QD@SiO 2 (acquired at excitation/emission wavelengths of 310/525 nm) decreases due to an electron transfer quenching processes. The assay has a linear calibration plot in the 0.05 to 30 μM DA concentration range and a 12.5 nM detection limit (at an S/N ratio of 3). The method was applied to the determination of DA in spiked human serum samples. Schematic presentation of a fluorometric dopamine (DA) assay by using silica-coated CdTe QDs (QD@SiO 2 ). DA is oxidized by oxygen under catalytic action of tyrosinase to form dopamine quinone, and this causes the quenching of fluorescence of QD@SiO 2 at excitation/emission wavelengths of 310/525 nm.