The Glucose Effect on Direct Electrochemistry and Electron Transfer Reaction of Glucose Oxidase Entrapped in a Carbon Nanotube‐Polymer Matrix

Abstract In this work, glucose oxidase (GOx) cross‐linking to a single‐wall carbon nanotubes (SWCNTs)‐poly(ethylenimine) (PEI) matrix is investigated using cyclic voltammetry (CV) for its direct electrochemistry and kinetics with presence of glucose. The electrochemistry of the bound flavin cofactor, flavin adenine dinucleotide (FAD) of the GOx, is impeded by glucose and recovered at absence of glucose, whereas a non‐specific sugar (e. g. sucrose) has no such effect. The Faradaic current of the GOx in CV decreases when the concentration of glucose increases, while the calculated electron transfer (ET) rate constant ( k 0 ) of the GOx presents a monotonic increment manner up to 144 % at 70 mM glucose concentration vs. absence of glucose in a deaerated electrolyte solution. The k 0 and Faradaic current changes demonstrate a strong linear relationship to logarithmic value of glucose concentration up to 20 mM. These results suggest that the entrapped GOx, when exposing to glucose, becomes deactivated in the direct electrochemistry. Further mechanistic analysis suggests the ET reaction of GOx shows a responsive correlation to the non‐ergodicity of those active GOx sites. A control experiment using pure FAD immobilized in the matrix doesn't show responses to glucose addition.