Abstract
GOD was immobilized onto polypyrrole (PPy) or poly(o-anisidine) (POA) coated Pt electrode to construct glucose sensitive biosensor. Because polymer film properties and enzyme activity affect the current response, PPy and POA synthesis conditions and also enzyme immobilization parameters were optimized in detail. The optimal monomer concentrations were determined as 25 and 50 mM for PPy and POA, respectively, whereas scan rate was 50 mV/s for both polymer films. In case of immobilization procedure, the optimal Chitosan (Chi), glucose oxidase (GOD) and glutaraldehyde (GAL) concentrations were determined as 0.5%, 2 mg/ml and 0.05% for PPy and 0.5%, 4 mg/ml and 0.075% for POA, respectively. Zinc oxide nanoparticles (ZnONP) were co-immobilized with GOD enzyme and it was revealed that ZnONP modification enhanced the efficiencies of both electrodes in terms of current responses and stabilities. Nyquist diagrams showed that enzyme electrodes were sensitive to glucose molecule and ZnONP modification improved the sensor efficiency.
Highlights
Glucose is one of the most analyzed components in biological fluids and foods
The biosensor response was monitored by the chronoamperometric technique at 0.60 V as current value that was measured depending on hydrogen peroxide oxidation which was formed by the glucose oxidase (GOD) activity in the glucose solution
In order to obtain the maximum current response, polymer film synthesizing parameters were optimized in terms of monomer concentration and scan rate
Summary
Glucose is one of the most analyzed components in biological fluids and foods. Compared to spectrophotometric and colorimetric methods, electrochemical methods have significant advantages in terms of simplicity, cost effective, quick way, excellent sensitivity and easy applicability. 1–3 Enzyme electrodes have been widely applied to construct biosensors for analyte determination.[4,5,6,7,8,9] Fabrication of the enzyme containing biosensor requires immobilization of the enzyme molecule onto/into the electrode surface. The poor electrochemical conductivity of Chi reduces the performance of the enzyme-based biosensor.[30] To overcome this problem, several strategies were developed by adding various materials in Chi matrix such as nanoparticles[15,32,34] ionic liquid,[29,33] or by modifying interface between electrode surface and Chi layer by nanoparticles,[7,31] Prussian Blue[30] and electropolymers.[31]. Construction of biosensor was optimized in terms of PPy and POA synthesis parameters, enzyme immobilization conditions and the amount of ZnONP by comparing current response in the glucose solution. Biosensor electrodes were optimized in terms of polymer synthesis conditions (monomer concentration and scan rate) and enzyme immobilization conditions (Chi, GOD and GAL concentration). Current values of each electrode that was constructed at different parameters were compared using glucose solution
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