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Title: Diboronate crosslinking: Introducing glucose specificity in glucose-responsive dynamic-covalent networks
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Author(s) / Creator(s):
; ; ; ; ; ;
Date Published:
Journal Name:
Journal of Controlled Release
Page Range / eLocation ID:
601 to 611
Medium: X
Sponsoring Org:
National Science Foundation
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  1. A disposable paper-based glucose biosensor with direct electron transfer (DET) of glucose oxidase (GOX) was developed through simple covalent immobilization of GOX on a carbon electrode surface using zero-length cross-linkers. This glucose biosensor exhibited a high electron transfer rate (ks, 3.363 s−1) as well as good affinity (km, 0.03 mM) for GOX while keeping innate enzymatic activities. Furthermore, the DET-based glucose detection was accomplished by employing both square wave voltammetry and chronoamperometric techniques, and it achieved a glucose detection range from 5.4 mg/dL to 900 mg/dL, which is wider than most commercially available glucometers. This low-cost DET glucose biosensor showed remarkable selectivity, and the use of the negative operating potential avoided interference from other common electroactive compounds. It has great potential to monitor different stages of diabetes from hypoglycemic to hyperglycemic states, especially for self-monitoring of blood glucose. 
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  2. 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 (k0) 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. Thek0and 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.

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