Melamine-Based Nanocomposites for Selective Dopamine and Uric Acid Sensing

Abstract

The formation process of carbon dots (CDs) is mostly polymerization; recently, studies on the polymerization of carbon families (graphene oxide and C60) have been receiving exciting attention. Herein, a protocol of prepolymerization and electropolymerization of 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 hydrothermal prepolymerization of melamine, and then the nanocomposite was formed in situ by electropolymerization of the CDs/carboxylated multiwalled carbon nanotubes (MWCNTs-COOH)-modified glassy carbon electrode (GCE) in KCl solution. Scanning electron microscopy, transmission electron microscopy, energy-dispersive spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, cyclic voltammetry, electrochemical impedance spectroscopy, and differential pulse voltammetry were used to characterize the properties of the nanocomposite. Under optimal conditions, the electrochemical sensor shows selectivity and a wide linear range from 0.1 to 10 μM for DA and 0.1 to 200 μM for UA, with the detection limit of 0.023 and 0.064 μM (S/N = 3) in the presence of AA, respectively. In addition, the proposed sensor was also applied to selectively test DA and UA in the presence of 500 μmol/L AA in real samples with satisfactory recovery.

Label-Free Electrochemical Sensing Using Glassy Carbon Electrodes Modified with Multiwalled-Carbon Nanotubes Non-Covalently Functionalized with Human Immunoglobulin G

“…Table 3 compares the analytical characteristics of our sensor with those electrochemical sensors based on CNTs for the simultaneous quantification of Do and UA published since 2021 [58][59][60][61][62][63][64][65][66][67]. Among them, Liao et al [60] reported detection limits for Do and UA comparable and higher to our sensor, respectively; Rattanaumpa et al [63] presented detection limits higher and comparable than our sensor for Do and UA, respectively, while Li et al [66] reported comparable detection limits to our sensor for both compounds.…”

Electrodeposition of paracetamol oxide for intelligent portable ratiometric detection of nicotine and ethyl vanillin β-d-glucoside

“…The relative standard deviation (RSD) of the redox peak current of the PA ox/SPCE is 1.96% and 1.60% (Fig. 5f), 40,41 respectively, so it is feasible to use electrodeposited PA ox as an internal reference probe.…”

A smart portable electrochemical sensor based on electrodeposited ferrocene-functionalized multiwalled carbon nanotubes for in vitro and in vivo detection of nicotine in tobacco samples

“…5E-G. The Randles-Sevcik formula, eqn (1), was used to calculate the active specific surface area of the electrode: 51,52 I p = 2.69 Â 10 5 n 3/2 AD 1/2 v 1/2 C 0 (1) where in n is the number of transfer electrons, A (cm 2 ) is the active specific surface area, D (cm 2 s À1 ) is related to the diffusion coefficient, v (V s À1 ) is the scan rate and C 0 (mol cm À3 ) is the concentration of [Fe(CN) 6 ] 3À/4À . When the electrolyte solution is 0.1 M KCl containing 5 mM [Fe(CN) 6 ] 3À/4À , n =1 and D = 6.20 Â 10 À6 (cm 2 s À1 ), then it can be calculated from eqn (1) that the active specific surface area of the SPCE is 0.0735 cm 2 , the MWCNTs/ SPCE is 0.0824 cm 2 and the FC-MWCNTs/SPCE is 0.112 cm 2 (Fig.…”

“…7F is a schematic diagram of the principle of adsorption detection. 51,54 The two slopes of the linear relationship between the two sections can be interpreted as single-layer adsorption followed by multi-layer adsorption, resulting in a decrease in the amplitude of the current. Fig.…”