Electrochemical detection of uric acid using graphite screen-printed electrodes modified with Prussian blue/poly(4-aminosalicylic acid)/Uricase

Abstract

This work investigates the use of electrochemical platforms containing polymeric films derived from 4-aminosalicylic acid (4-ASA) modified with the enzyme urate oxidase (UOx) for quantification of uric acid (UA) in urine samples. Electropolymerization of 4-ASA was investigated over carbon graphite electrodes (CGE). As a mediator of the enzymatic product, Prussian blue (PB) was also electrodeposited over the working electrodes. The film provides electrochemical activity with a homogeneous coverage, and the use of PB does not alter the electrochemical profile or the film morphology. Analysis of infrared spectra demonstrates the presence of the unchanged carboxyl groups and suggests that polymerization begins at the nitrogen atom. The biosensor was developed on graphite screen-printed electrodes with all optimization performed on CGE. UOx was immobilized through physical adsorption and the proposed sensor was coupled to a flow cell in a flow injection analysis (FIA) system with amperometric detection. The flow rate, injection volume, and pH of the UA solution were optimized at 2.10mLmin−1, 200μL, and 8.27, respectively. Under these conditions, a relative standard deviation of 2.15% (n=10) was achieved for UA detection. A linear range of 10 to 200μM was obtained for UA determination with a limit of detection of 3.0μM. UA recovery from amended urine samples was 97.4% (±2.4).