An electrochemical biosensor based on nanoporous stainless steel modified by gold and palladium nanoparticles for simultaneous determination of levodopa and uric acid

In this paper, an electrochemical biosensor based on gold and palladium nano particles-modified nanoporous stainless steel (Au-Pd/NPSS) electrode has been introduced for the simultaneous determination of levodopa (LD) and uric acid (UA). To prepare the electrode, the stainless steel was anodized to fabricate NPSS and then Cu was electrodeposited onto the nanoporous steel by applying the multiple step potential. Finally, the electrode was immersed into a gold and palladium precursor's solution by the atomic ratio of 9:1 to form Au-Pd/NPSS through the galvanic replacement reaction. Morphological aspects, structural properties and the electroanalytical behavior of the Au-Pd/NPSS electrode were studied using field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), electrochemical impedance spectroscopy (EIS) and voltammetric techniques. Also, differential pulse voltammetry (DPV) was used for the simultaneous determination of LD and UA. According to results, the surface of Au-Pd/NPSS electrode contained Au and Pd nanoparticles with an average diameter of 75 nm. The electrode acted better than Au/NPSS and Pd/NPSS electrodes for the simultaneous determination of LD and UA, with the peak separation potential of about 220 mV. Also, the calibration plot for LD was in two linear concentration ranges of 5.0-10.0 and 10.0-55.0 mu mol L-1 and for UA, it was in the range of 100-1200 mu mol L-1. The detection limit for LD and UA was 0.2 and 15 mu mol L-1, respectively. The modified electrode had a good performance for LD and UA detection in urine, blood serum and levodopa C-Forte tablet. (C) 2016 Elsevier B.V. All rights reserved.