The Preparation And Application Of The Third-generation Glucose Sensor Microelectrode

The direct electron transfer?DET?process between glucose oxidase?GOx/GOD?and electrode has received great attention,since the concept of third-generation glucose sensor was proposed.Understanding the DET action of GOx on the surface of electrode is significant to construct a new third-generation glucose sensor.In this paper,the porous poly?3,4-ethylenedioxythiophene??PEDOT?modification film on carbon fiber microelectrode was simply constructed by potentiosatic method,and the effective area of modified electrode is 100-fold higher than the geometric area of bare microelectrode.Additionally,the electrochemical reaction rate constant?k_s?of modified microelectrde is close to that of the gold and platinum electrode.The enzyme,GOx was immobilized on the surface of PEDOT modified electrode simply and effectively by electric adsorption,and the DET process of GOx was also constructed under the help of PEDOT.The electrochemical property of enzyme electrode was characterized by cyclic voltammetry?CV?.It demonstrated that one proton and two electrons participate in the DET process of GOx.On the other hand,a more negative redox potential of FAD?active center of GOx?was observed due to the above DET process.The lower redox potential of FAD indicated that the proposed enzyme electrode has better selectivity,which has been verified in the determination of glucose content in wine and sports drink samples.Furthermore,the amperometric response of the sensor was linear over range from 0.5 m M to 15 m M for glucose with a sensitivity of 8.5?A·cm^-2·m M^-1,and the Michaelis-Menten constant was calculated as 6.5 m M.The sensor retained 81.3%relative current response after 60 days storage.The proposed strategy for the third-generation glucose sensor has also been successfully utilized on a screen-printed electrode?SPE?.The SPE-PEDOT-GOx sensor showed the satisfactory performance with a wide linear range?1–7 m M?,and the Michaelis-Menten constant of 2.3 m M.Furthermore,the enzyme activity of GOx in air-sat'd surroundings is larger than that indeoxygenated surroundings,and the maximum enzyme catalysis rate is 10-fold larger than that under deoxygenated surroundings.The results of microscale and conventional scale electrode suggested that the proposed strategy is a practical method,which can be used in the development of third generation glucose sensors with special size and shape.