A new disposable microfluidic electrochemical paper-based device (ePAD) consisting of two spot sensors in the same working electrode for the simultaneous determination of uric acid and creatinine was developed. The spot 1 surface was modified with graphene quantum dots for direct uric acid oxidation and spot 2 surface modified with graphene quantum dots, creatininase and a ruthenium electrochemical mediator for creatinine oxidation. The ePAD was employed to construct an electrochemical sensor (based on square wave voltammetry analysis) for the simultaneous determination of uric acid and creatinine in the 0.010-3.0 µmol L-1 range. The device showed excellent analytical performance with a very low simultaneous detection limit of 8.4 nmol L-1 to uric acid and 3.7 nmol L-1 to creatinine and high selectivity. The ePAD was applied to the rapid and successful determination of those clinical biomarkers in human urine samples.
Keywords: Clinical samples; Creatininase; Disposable electrochemical device; Graphene quantum dots (GQDs); Simultaneous detection.
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