ZnS Nanoparticles-decorated Composite Graphene Paper: A Novel Flexible Electrochemical Sensor for Detection of Dopamine

Dopamine (DA) is a significant catecholamine neurotransmitter in human metabolism, and DA is related to several critical illnesses. Accurate detection of DA is important to diagnose these diseases. Here, we demonstrated a flexible electrochemical sensor, ZnS nanoparticles decorated composite graphene paper electrode (CGPE), for the detection of DA. CGPE was prepared via mold-casting method using ZnS/graphene oxide dispersion followed by thermal reduction treatment. The characterization of the flexible CGPE was investigated through various techniques. The electrochemical tests were carried out to study the electrocatalytic properties of CGPE against DA oxidation. Compared to graphene paper electrode (GPE), the oxidation of DA occurred at about 250 mV lower potential on CGPE, and peak current density increased about 2 times. Our sensor exhibited high sensitivity in linear range of 0.1-2300 mu M of DA with a limit of detection (LOD) of 0.0042 mu M. Furthermore, CGPE has selectively detected DA even in the medium containing AA and UA which are biologically active interfering molecules. Besides, the sensor showed many attractive properties such as high durability, stability, and reproducibility and it was successfully applied for the determination of DA in real samples for practical applications.