Dopamine (DA) is an important neurotransmitter associated with nerve signaling and some diseases. Therefore, it is very significant to detect DA in patients to regulate body function. Compared with other traditional methods, these electrochemical sensors have their intrinsic advantages of high sensitivity, celerity, simplicity, and economy. In this article, a graphene quantum dots/multiwalled carbon nanotubes (GQDs-MWCNTs) composite-based ultrasensitive electrochemical sensor for detecting dopamine (DA) was fabricated. As the carbon nanomaterials, GQDs have large surface areas to improve the conductivity of the electrodes, and the MWCNTs are excellent electrode materials. As expected, the sensor has excellent selectivity of dopamine among other interfering bioanalytes. Under optimum conditions, this electrochemical sensor exhibited maximum performance toward DA determination with good linearity in a broad linear range of 0.005 to 100.0 μM with the detection limit of 0.87 nM (3S/N). Furthermore, this electrochemical sensor was successfully applied for detecting DA in human serum, and it was the first example to measure DA secreted from live PC12 cells with excellent performance.

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