Abstract
Urea Amperometric biosensor was obtained on the base of nanostructured polypyrrole (PPy) and poly ortho- phenylenediamine (POPDA). The optimal conditions for monomer electropolymerization were determined. The effect of supporting electrolyte and number of deposition cycles on the OPDA and Py electropolymerization were studied. It was proved that POPDA and PPy were affected by pH changes and responded to the ammonium, product of urease catalyzed reaction. SEM images of the modified Pt/PPy electrode were presented. The cycle voltammograms and chrono amperometric curves of Pt/POPDA/urease and Pt/PPy/urease electrodes were studied. A good linear relationship was observed for Pt/POPDA/urease electrode in a concentration range from 6.7 to 54 mMurea. For Pt/PPy/urease electrode the linear relation in the range from 0.02 to0.16 mMurea was determined. The entrapped carbon nanotubes (CNT) in PPy film and the bipolymer layers were prepared for construction of Pt/PPy/CNT/urease, Pt/POPDA/PPy/urease and Pt/PPy/POPDA/urease biosensors. Obviously, the addition of POPDA to the composition of the two biosensors (Pt/PPy/POPDA/urease and Pt/POPDA/PPy/urease) reduced their sensitivity to urea. Pt/РPy/CNT/urease and Pt/РPy/ urease biosensors were 173 and 138 times more sensitive to urea than biosensor without PPy (Pt/POPDA/urease biosensor). It was found, that the performance of Pt/PPy/CNT/urease electrode was the best from the five obtained biosensors: linear range of urea concentrations—from 0.02 to0.16 mM; sensitivity—15.22 μA/mM and detection limit— 0.005 mM urea.
Highlights
The urea concentration in serum or urine is an indicator of kidney diseases, as well as diabetes, and analysis in clinical laboratories is frequently used
Urea Amperometric biosensor was obtained on the base of nanostructured polypyrrole (PPy) and poly orthophenylenediamine (POPDA)
A good linear relationship was observed for Pt/POPDA/urease electrode in a concentration range from 6.7 to 54 mM urea
Summary
The urea concentration in serum or urine is an indicator of kidney diseases, as well as diabetes, and analysis in clinical laboratories is frequently used. The using of carbon nanotubes (CNT) as mediators of the electron transfer from the enzyme molecules to the electrode surface is often applied Their unique electronic properties suggest that CNT have the ability to promote the electron transfer reactions of biomolecules in electrochemistry [3]. Their mechanical properties, high-aspect ratio, electrical conductivity and chemical stability make CNT perfect for a wide range of applications that include fabrication of urease biosensors [4]. A variety of urease biosensors with high sensitivity and excellent reproducibility based on nanostructured polypyrrole [5,6,7,8,9], poly ortho-phenylenediamine [10,11] and carbon nanotubes [12,13] has been reported. Preparation of urea amperometric biosensor based on nanostructured polypyrrole, poly ortho-phenylenediamine, multi-layered nanostructured substrates and comparing the performance of obtained biosensors
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