Template synthesis of maghemite nanoparticle in carboxymethyl cellulose and its application for electrochemical cabergoline sensing.

Maghemite (γ-Fe2O3) nanoparticles were produced via coprecipitation onto carboxymethyl cellulose matrix based templates followed by calcination. The resulting maghemite nanoparticles were characterized by Fourier transform infrared spectra, X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The magnetization measurement of as-synthesized γ-Fe2O3 displayed superparamagnetic characteristics at room temperature. Then, a novel maghemite nanoparticles carbon paste modified electrode was developed for determination of cabergoline. The modified electrode has an outstanding catalytic effect on the oxidation current of cabergoline and the mechanism was studied using cyclic voltammetry. The oxidation peak current was proportional to the concentration of cabergoline from 1×10-7 to 3.5×10-5molL-1 with a detection limit of 3×10-8molL-1 at signal to noise ratio of 3. The proposed method was examined as a selective, simple and precise method for voltammetric determination of cabergoline in plasma and pharmaceutical samples.

Simultaneous determination of cysteine, uric acid and tyrosine using Au-nanoparticles/poly(E)-4-(p-tolyldiazenyl)benzene-1,2,3-triol film modified glassy carbon electrode.

A novel Au nanoparticles/poly(E)-4-(p-tolyldiazenyl)benzene-1,2,3-triol (AuNPs/PTAT) film modified glassy carbon electrode (AuNPs/PTAT/GCE) was fabricated for the simultaneous determination of three antioxidants named, cysteine (Cys), uric acid (UA) and tyrosine (Tyr). The bare glassy carbon electrode (GCE) fails to separate the oxidation peak potentials of these molecules, while PTAT film modified electrode can resolve them. Electrochemical impedance spectroscopy (EIS) study indicates that the charge transfer resistance of bare electrode increased as (E)-4-(p-tolyldiazenyl)benzene-1,2,3-triol was electropolymerized at the bare electrode. Furthermore, EIS exhibits enhancement of electron transfer kinetics between analytes and electrode after electrodeposition of Au nanoparticles. Differential pulse voltammetry results show that the electrocatalytic current increases linearly in the ranges of 2-540µmolL(-1) for Cys, 5-820µmolL(-1) for UA and 10-560µmolL(-1) for Tyr with detection limits (S/N=3) of 0.04µmolL(-1), 0.1µmolL(-1) and 2µmolL(-1) for Cys, UA and Tyr, respectively. The proposed method was successfully applied for simultaneous determination of Cys, UA and Tyr in human urine samples.