Development and Application of a Voltammetric Biosensor Based on Polypyrrole/uricase/graphene for Uric Acid Determination

Abstract In the present paper a voltammetric biosensor based on platinum electrode and polypyrrole / uricase / graphene composite, named Pt‐PPy/UOx/Grap has been successfully prepared and validated for uric acid (UA) determination in real samples. The electrochemical behavior has been evaluated by employing cyclic voltammetric. The charge transfer coefficient, α, and the charge transfer rate constant, κs, for electron transfer between PPy/UOx/Grap and Pt were calculated as 0.71, in average, and 48.3 s −1 , respectively. Under optimized conditions for the composite (2.5 U mL −1 of UOx, 0.3 mg mL −1 of Grap and 2.9 mmol L −1 of pyrrole) and for the analysis (pH 7.0 in 0.1 mol L −1 phosphate buffer) the method was validated for UA determination at human urine and showed good linearity to UA from 2 up to 24 nmol L −1 (r=0.993) with limits of detection and quantification of 0.541 and 1.805 nmol L −1 , respectively. The results obtained for the UA determination at urine presented a relative error lower than 5 %, showing the good performance of the method developed and potential application in UA clinical analysis.