On the Adsorption of Glucose Oxidase at a Gold Electrode

Abstract

In this paper, the shape and size of glucose oxidase (GO) adsorbed on a gold electrode was determined by. ellipsometry. It was concluded that GO is a prolate ellipsoid molecule with a major axis of 140A and a minor axis of 50A. Two orientations of the molecule on the surface were observed: the major axis can be perpendicular to the surface (standing position) or parallel to the surface (lying position). Above a certain coverage, enzymes in the standing position are not stable and undergo a transition to the lying position due to increasing intermolecular interaction. In the lying position, the enzyme-and-substrate contact area is large, and gradual unfolding occurs, leading to a significant change in the structure of the protein. It was possible to detect direct electron transfer between a gold electrode and glucose oxidase. After a short contact time, two almost overlapping electron transfer processes were distinguished, but were gradually transformed to a single response that was characteristic for adsorbed FAD, thus showing that significant changes in the protein structure occur, leading the deactivation of the enzyme.

Direct Electron Transfer of Glucose Oxidase Molecules Adsorbed onto Carbon Nanotube Powder Microelectrode

“…13,14 In conclusion, we demonstrated that GOD has a special electrochemical response at CNT. The kinetic parameters were also calculated.…”

“…7,8 Various methods have been used to achieve this goal: modifying the electrode surface with promoters, 9 modifying the redox protein with electron replay, 10 immobilizing the enzyme in redox polymer matrixes 11 and adsorbing the enzyme on an electrode surface, 12 for example. Some groups studied the electrochemical response of adsorbing glucose oxidase (GOD) at some specially treated electrodes, for example gold, 13 anodized GC 14 and graphite 15 electrodes; the results show that GOD undergoes direct electron transfer at these electrodes.…”

Permselective Behavior of an Electrosynthesized, Nonconducting Thin Film of Poly(2-naphthol) and Its Application to Enzyme Immobilization

“…Here, the immobilization of the enzyme glucose oxidase (GOD) was investigated by electrochemical polymerization of 2-NAP onto platinum surface in the presence of GOD in the electrodeposition solution. Besides a plain mechanical entrapment of the enzyme during the ®lm growth, GOD immobilization can mainly occur by adsorption at the platinum surface [24,25]. Therefore, the platinum electrode was allowed to stand at open circuit in the deposition solution before the electrochemical deposition step in order to control any enzyme adsorption.…”

Electrochemical Biosensing Platforms Using Phthalocyanine‐Functionalized Carbon Nanotube Electrode

“…Furthermore, the current response totally disappears during stirring, indicating that GOD is only weakly adsorbed at the MWNTs. The adsorbed GOD at MWNTs has been shown to lose its catalytic activity for glucose [27], just as it occurred with other adsorbing methods [37,38]. To maintain the electrocatalytic ability and improve the stability of GOD at MWNTs, we entrapped GOD within an insulating film.…”