Simultaneous electrochemical sensing of cysteine, uric acid and tyrosine using a novel Au-nanoparticles/poly-Trypan Blue modified glassy carbon electrode

•An AuNP/poly-TrB composite modified GC electrode was fabricated.•This sensor shows electrocatalytic property towards the oxidation of Cys.•The applicability of biosensor was investigated in biological samples.

In this study, Au-nanoparticles/poly-Trypan Blue modified glassy carbon electrode (AuNPs/poly-TrB/GCE) was fabricated for the simultaneous determination of cysteine (Cys), uric acid (UA) and tyrosine (Tyr). There are limitations in bare glassy carbon electrode (GCE) in showing clear oxidation peaks for Cys, UA and Tyr; whereas AuNPs/poly-TrB modified electrode completely separated the voltammetric signals of Cys, UA and Tyr at + 0.40, + 0.58 and + 0.90 V, respectively (vs. Ag/AgCl electrode). This modified electrode shows excellent electrocatalytic activity towards the oxidation of Cys with a potential shift about 460 mV to a less positive potential. Under optimized experimental conditions, the detection limits of Cys, UA and Tyr were calculated as 0.006, 0.07 and 0.008 μmol L− 1, respectively, at this simple construction sensor. Finally, the fabricated sensor was satisfactorily used for the simultaneous determination of these molecules in human biological samples.

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