Tungsten disulfide quantum dots (WS2 QDs) as a fluorescence probe for detection of dopamine (DA)

Imbalance in the levels of dopamine as a neurotransmitter has led to several physiological and psychological disorders; therefore detection of dopamine in patients is necessary to regulate body functions. A simple, high-performance method for determination of dopamine levels in real samples using a tungsten disulfide compound was employed. Tungsten disulfide(WS2) was synthesized by hydrothermal method using tungsten nitrate and thiourea and characterized by Transmission electron microscopy(TEM), Scanning electron microscopy(SEM), energy-dispersive X-Ray(EDX), energy-dispersive X-ray mapping analysis, and Fourier transform infrared(FTIR). The intensity of fluorescence quenching of this compound was tested in the presence of different molecules, but the amount of fluorescence decreased only with increasing dopamine. Therefore, such a quenching effect can be used to selectively detect dopamine (DA). The probe has a linear response range in the 50 μM to 450 μM with a detection limit of 20 µM (at S/N = 3). It was successfully applied to the determination of dopamine (DA) in spiked to serum samples. The mechanism of dopamine measurement using tungsten is such that WS2 as a catalyst and due to the active sites on its surface converts dopamine to form thin (poly-dopamine), which is placed on the surface of WS2 and causes fluorescence intensity to decrease.