Abstract
Biosensors for the determination of glucose concentration have a great significance in clinical diagnosis, and in the food and pharmaceutics industries. In this research, short-chain polyaniline (PANI) and polypyrrole (Ppy)-based nanocomposites with glucose oxidase (GOx) and 6 nm diameter AuNPs (AuNPs(6 nm)) were deposited on the graphite rod (GR) electrode followed by the immobilization of GOx. Optimal conditions for the modification of GR electrodes by conducting polymer-based nanocomposites and GOx were elaborated. The electrodes were investigated by cyclic voltammetry and constant potential amperometry in the presence of the redox mediator phenazine methosulfate (PMS). The improved enzymatic biosensors based on GR/PANI-AuNPs(6 nm)-GOx/GOx and GR/Ppy-AuNPs(6 nm)-GOx/GOx electrodes were characterized by high sensitivity (65.4 and 55.4 μA mM−1 cm−2), low limit of detection (0.070 and 0.071 mmol L−1), wide linear range (up to 16.5 mmol L−1), good repeatability (RSD 4.67 and 5.89%), and appropriate stability (half-life period (τ1/2) was 22 and 17 days, respectively). The excellent anti-interference ability to ascorbic and uric acids and successful practical application for glucose determination in serum samples was presented for GR/PANI-AuNPs(6 nm)-GOx/GOx electrode.
Highlights
The design and wide application of electrochemical biosensors in nanoscience, nanotechnology, medicine, environmental, and food monitoring has significantly intensified during the past decade [1,2,3,4,5,6]
The potential of anodic peaks (Epa) of graphite rod (GR) electrodes modified by PANI-glucose oxidase (GOx)/GOx, Ppy-GOx/GOx, PANI-AuNPs(6 nm)-GOx/GOx or Ppy-AuNPs(6 nm)-GOx/GOx composites was determined at +0.12 V vs. Ag/AgCl(3 mol L−1 KCl)
We demonstrated the improved properties and analytical parameters of a glucose biosensor developed using dispersed nanocomposites based on GOx and AuNPs(6 nm) embedded within the conducting polymers PANI or Ppy
Summary
The design and wide application of electrochemical biosensors in nanoscience, nanotechnology, medicine, environmental, and food monitoring has significantly intensified during the past decade [1,2,3,4,5,6]. Glucose oxidase (GOx) does not directly transfer electrons towards conventional electrode materials, because a thick protein layer surrounds the active site of GOx based on the flavin adenine dinucleotide (FAD) redox center, and this protein layer is forming the intrinsic barrier to charge transfer from the active site [10,15,21]. In the presence of oxygen in the solution, GOx immobilized on graphite electrodes catalyzes the oxidation of glucose into gluconolactone following hydrolysis to gluconic acid and provides the selectivity for the electrochemical sensor [2,14,21,22,23,24,25]. The development of miniaturized enzymatic biosensors with the size ranging from several millimeters down to a few micrometers requires the combination of knowledge in electrochemistry, material science, polymer synthesis, enzymology and biological chemistry [4,20]
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