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

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, , and the charge transfer rate constant, s, for electron transfer between PPy/UOx/Grap and Pt were calculated as 0.71, in average, and 48.3s(-1), respectively. Under optimized conditions for the composite (2.5UmL(-1) of UOx, 0.3mgmL(-1) of Grap and 2.9mmolL(-1) of pyrrole) and for the analysis (pH7.0 in 0.1molL(-1) phosphate buffer) the method was validated for UA determination at human urine and showed good linearity to UA from 2 up to 24nmolL(-1) (r=0.993) with limits of detection and quantification of 0.541 and 1.805nmolL(-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.