Glucose biosensors based on poly(o-aminophenol)

Abstract

some advantages over the conducting film formed in acidic media. These characteristic properties of POAP synthesized in neutral media (thickness uniformity and compactness, and low permeability) have practical applicability. POAP has usefully been employed in the development of different types of sensors, mainly biosensors based on immobilized enzymes.3 The development of glucose biosensors has received considerable attention because the determination of glucose concentration is very important in clinical applications. Most glucose measurements are based on the immobilization of glucose oxidase (GOx) for detecting hydrogen peroxide concentration, which is produced from the GOx enzyme reaction. Several glucose biosensors based on POAP are reported in the literature.4‒9 In most cases, hydrogen peroxide liberated by the enzymatic reaction is detected by measuring its oxidation current on the base electrode material (platinum, gold, glassy carbon, carbon paste, etc.). The amperometric response characteristics of the enzyme electrodes based on POAP are affected by the polymerization cycle number, the pH of the detection solution, applied potential used in the determination, and the presence of electroactive (interfering) compounds. The maximum value of the response current for POAP was obtained for a polymerization cycle number about 15. The compactness of POAP synthesized at a small number of potential cycles prevents the diffusive penetration of dissolved oxygen.9 However, thick films show a long response time and low sensitivity, but result in a wider linear response range. It has been suggested that when the number of cycles is lower than 15, then the amount of enzyme entrapped in the POAP film gradually increases with the increase of the polymerization cycle number. However, when the number of cycles is higher than 15, the amount of GOx incorporated into POAP films decreases. In respect to pH, the response current of the sensors5 increases with the increase of the pH value, and the maximum response was observed at pH 7.0.