Voltammetric Signals Of Dopamine Research Articles

Graphite paste electrodes modified with a sulfo-functionalized metal-organic framework (type MIL-101) for voltammetric sensing of dopamine.

The metal-organic frameworks MIL-101 and sulfo-MIL-101 were used to modify graphite paste electrodes (GPEs) to obtain sensors for determination of dopamine (DA). Taking advantage of the catalytic activity of metal-organic frameworks (MOFs) and of the electrical conductivity of graphite, the modified GPEs show enhanced voltammetric responses, and the GPE modified with the sulfo-MOF displays superior sensitivity when operated at a working potential of -0.4 to 0.8V (vs. Ag/AgCl). The sensor works in the 0.07 to100 μM DA concentration range and has a 43nM detection limit. It is concluded that the sulfo group provides open sites for efficient electrostatic and hydrogen bonding interactions, which facilitates electron transfer. Graphical abstractSchematic representation of the structure of the sulfo-functionalized MOF (sulfo-MIL-101) and the different voltammetric signals of dopamine at the graphite paste electrodes (GPEs) modified with sulfo-MIL-101 and the parent MOF (MIL-101).

Simultaneous determination of neurotransmitters and a neuroprotector in human blood serum and urine samples using a diazonium grafted gold nanoparticle film electrode

An electrode modified with a film of aminophenyl grafted gold nanoparticles (AP-AuNPs) was used for the simultaneous determination of the neurotransmitters dopamine (DA) and adenosine (AD) in the presence of the neuroprotector guanosine (GN) at physiological pH. A bare glassy carbon electrode was unable to resolve the voltammetric signals of DA, GN and AD as a result of surface fouling caused by the oxidation products. However, the electrode modified with an AP-AuNP film separated the voltammetric signals of DA, GN and AD with potential differences of 800 mV between DA and GN and 340 mV between GN and AD; their oxidation peak currents were also enhanced. The simultaneous determination of DA, GN and AD was successfully achieved at the electrode modified with an AP-AuNP film using differential pulse voltammetry. The amperometric current response increased linearly with increasing concentrations of DA, GN and AD in the ranges 4.0 × 10−8 to 1 × 10−4 M, 7.0 × 10−8 to 5 × 10−5 M and 2.0 × 10−7 to 1 × 10−4 M, respectively, and the detection limits were 8.0 × 10−11 M for DA, 2.6 × 10−8 M for GN and 5.1 × 10−8 M for AD (S/N = 3). The practical application of the electrode modified with an AP-AuNP film was demonstrated by simultaneously determining the concentrations of DA, GN and AD in human blood serum and urine samples.

Poly(2-amino-5-(4-pyridinyl)-1, 3, 4-thiadiazole) film modified electrode for the simultaneous determinations of dopamine, uric acid and nitrite

Poly(2-amino-5-(4-pyridinyl)-1,3,4-thiadiazole) (PAPT) modified glassy carbon electrode (GCE) was fabricated and used for the simultaneous determinations of dopamine (DA), uric acid (UA) and nitrite (NO2 −) in 0.1 mol L−1 phosphate buffer solution (PBS, pH 5.0) by using cyclic voltammetry and differential pulse voltammetry (DPV) techniques. The results showed that the PAPT modified GCE (PAPT/GCE) not only exhibited electrocatalytic activities towards the oxidation of DA, UA and NO2 − but also could resolve the overlapped voltammetric signals of DA, UA and NO2 − at bare GCE into three strong and well-defined oxidation peaks with enhanced current responses. The peak potential separations are 130 mV for DA–UA and 380 mV for UA–NO2 − using DPV, which are large enough for the simultaneous determinations of DA, UA and NO2 −. Under the optimal conditions, the anodic peak currents were correspondent linearly to the concentrations of DA, UA and NO2 − in the ranges of 0.95–380 μmol L−1, 2.0–1,000 μmol L−1 and 2.0–1,200 μmol L−1 for DA, UA and NO2 −, respectively. The correlation coefficients were 0.9989, 0.9970 and 0.9968, and the detection limits were 0.2, 0.35 and 0.6 μmol L−1 for DA, UA and NO2 −, respectively. In 0.1 mol L−1 PBS pH 5.0, the PAPT film exhibited good electrochemical activity, showing a surface-controlled electrode process with the apparent heterogeneous electron transfer rate constant (k s) of 25.9 s−1 and the charge–transfer coefficient (α) of 0.49, and thus displayed the features of an electrocatalyst. Due to its high sensitivity, good selectivity and stability, the modified electrode had been successfully applied to the determination of analytes in serum and urine samples.