Fluorometric dopamine assay based on an energy transfer system composed of aptamer-functionalized MoS2 quantum dots and MoS2 nanosheets

The authors describe a fluorometric strategy for the determination of dopamine (DA). It is based on the use of aptamer-functionalized MoS2 quantum dots (QDs) and MoS2 nanosheets (NSs). The QDs and NSs were extensively characterized with regard to their physical and chemical properties using methods such as TEM, XRD, FT-IR, EDX and molecular spectroscopies. The aptamer against dopamine was labeled with QDs acting as the energy donor in an energy transfer system, while the NSs serve as the energy acceptor. Under the optimal conditions, the fluorescence (FL) intensity (best measured at excitation/emission peaks of 315/412 nm) increases with increasing DA concentration in the range from 0.1 nM to 1000 nM, with a lower detection limit of 45 pM. The method was successfully applied to the determination of DA in complex matrices. In our perception, the method has a wide scope in that it may be extended to other biomolecules for which respective aptamer are available. The QDs show excellent optical properties, good stability, low cytotoxicity, and may also be applied to fluorometric imaging of live cells. Graphical abstract A "turn-on" fluorometric aptasensor for the determination of dopamine (DA) was established based on aptamer-functionalized molybdenum disulfide quantum dots (MoS2 QDs) and MoS2 nanosheets. This assay exhibits high selectivity and sensitivity with a detection limit as low as 45 pM.