Melamine-Based Nanocomposites for Selective Dopamine and Uric Acid Sensing

The formation process of carbon dots (CDs) is mostlypolymerization; recently, studieson the polymerizationof carbon families (graphene oxide and C-60) have been receivingexciting attention. Herein, a protocol of prepolymerization and electropolymerizationof monomer (melamine) and nanomonomer (CDs fixed melamine residues)was proposed to prepare a nanocomposite for selective dopamine (DA)and uric acid (UA) sensing. The nanomonomer was prepared by hydrothermalprepolymerization of melamine, and then the nanocomposite was formedin situ by electropolymerization of the CDs/carboxylated multiwalledcarbon nanotubes (MWCNTs-COOH)-modified glassy carbon electrode (GCE)in KCl solution. Scanning electron microscopy, transmission electronmicroscopy, energy-dispersive spectroscopy, X-ray diffraction, Fouriertransform infrared spectroscopy, cyclic voltammetry, electrochemicalimpedance spectroscopy, and differential pulse voltammetry were usedto characterize the properties of the nanocomposite. Under optimalconditions, the electrochemical sensor shows selectivity and a widelinear range from 0.1 to 10 mu M for DA and 0.1 to 200 mu Mfor UA, with the detection limit of 0.023 and 0.064 mu M (S/N= 3) in the presence of AA, respectively. In addition, the proposedsensor was also applied to selectively test DA and UA in the presenceof 500 mu mol/L AA in real samples with satisfactory recovery.