Unadulterated Glucose Biosensor Based on Direct Electron Transfer of Glucose Oxidase Encapsulated Chitosan Modified Glassy Carbon Electrode

Abstract

Glucose oxidase (GOD) was encapsulated in chitosan matrix and immobilized on a glassy carbon electrode, achieving direct electron transfer (DET) reaction between GOD and electrode without any nano-material. On basis of such DET, a novel glucose biosensor was fabricated for direct bioelectrochemical sensing without any electron-mediator. GOD incorporated in chitosan films gave a pair of stable, well-defined, and quasireversible cyclic voltammetric peaks at about À 0.284 (E pa ) and À 0.338 V (E pc ) vs. Ag/AgCl electrode in phosphate buffers. And the peak is located at the potentials characteristic of FAD redox couples of the proteins. The electrochemical parameters, such as midpoint potential (E 1/2 ) and apparent heterogeneous electron-transfer rate constants (k s ) were estimated to À 0.311 V and 1.79 s À1 by voltammetry, respectively. Experimental results indicate that the encapsulated GOD retains its catalytic activity for the oxidation of glucose. Such a GOD encapsulated chitosan based biosensor revealed a relatively rapid response time of less than 2 min, and a sufficient linear detection range for glucose concentration, from 0.60 to 2.80 mmol L À1 with a detection limit of 0.10 mmol L À1 and electrode sensitivity of 0.233 mA mmol À1. The relative standard deviation (RSD) is under 3.2% (n ¼ 7) for the determination of practical serum samples. The biologic compounds probably existed in the sample, such as ascorbic acid, uric acid, dopamine, and epinephrine, do not affect the determination of glucose. The proposed method is satisfactory to the determination of human serum samples compared with the routine hexokinase method. Both the unique electrical property and biocompatibility of chitosan enable the construction of a good bio-sensing platform for achieved DET of GOD and developed the third-generation glucose biosensors.

Direct electron transfer of glucose oxidase immobilized in an ionic liquid reconstituted cellulose–carbon nanotube matrix

“…The reason is that the dissolved oxygen and GOx take part in the non-electrochemical oxidation of glucose. This phenomenon can be explained by the following, previously proposed, mechanism [27,28]:…”

Electrochemical sensing of glucose using polyaniline nanofiber dendrites‐amperometric and impedimetric analysis

“…The development of glucose biosensors constitutes a frontier area of research in the field of sensors and its accurate detection in presence of interfering agents is being extensively analyzed 1–3. In this context, the efficacy of glucose oxidase has been demonstrated and among several studies pertaining to glucose sensors, mention may be made of the following: (i) use of oxygen as a cosubstrate with generation and detection of hydrogen peroxide4; (ii) incorporation of electron‐mediators such as ferrocene, quinones, viologens, and so forth5–7; and (iii) direct electron transfer between the electrode and the enzyme 8. The glucose sensors have in general been fabricated by immobilizing the enzyme onto the electrode surface in view of the satisfactory features such as noncontamination and minimal pretreatment.…”

Biosensors in clinical chemistry — 2011 update

“…Glucose remains the model analyte of choice for demonstration of concepts toward improving biosensor performance, in particular electrochemical biosensors, owing to the widespread use of biosensors for blood glucose in systems for point-of-care testing, ease of working with the enzyme glucose oxidase, and a large literature base documenting known performance problems with state-of-the-art glucose biosensors. Newer enzyme immobilization matrices include sol-gel composite films [85,86], polymeric microparticles [87] and chitosan [88], to achieve direct electron transfer between bioreactions and electrodes, without the need for nanoparticles. Performance advantages of direct electron transfer include faster response times (~10 s).…”