Electron Transfer Of Glucose Oxidase Research Articles

Investigation of Direct Electron Transfer of Glucose Oxidase on a Graphene-CNT Composite Surface: A Molecular Dynamics Study Based on Electrochemical Experiments.

Graphene and its variants exhibit excellent electrical properties for the construction of enzymatic interfaces. In particular, the direct electron transfer of glucose oxidase on the electrode surface is a very important issue in the development of enzyme-based bioelectrodes. However, the number of studies conducted to assess how pristine graphene forms different interfaces with other carbon materials is insufficient. Enzyme-based electrodes (formed using carbon materials) have been extensively applied because of their low manufacturing costs and easy production techniques. In this study, the characteristics of a single-walled carbon nanotube/graphene-combined enzyme interface are analyzed at the atomic level using molecular dynamics simulations. The morphology of the enzyme was visualized using an elastic network model by performing normal-mode analysis based on electrochemical and microscopic experiments. Single-carbon electrodes exhibited poorer electrical characteristics than those prepared as composites with enzymes. Furthermore, the composite interface exhibited 4.61- and 2.45-fold higher direct electron efficiencies than GOx synthesized with single-carbon nanotubes and graphene, respectively. Based on this study, we propose that pristine graphene has the potential to develop glucose oxidase interfaces and carbon-nanotube-graphene composites for easy fabrication, low cost, and efficient electrode structures for enzyme-based biofuel cells.

Direct Electron Transfer of Glucose Oxidase on Pre-Anodized Paper/Carbon Electrodes Modified through Zero-Length Cross-Linkers for Glucose Biosensors.

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.

Detecting low-brominated diphenyl ethers by highly sensitive biosensors based on the blocking effect on glucose oxidase

A novel GOD∼/AuNPs#rGO-CHIT/GC electrode was fabricated to realize the direct electron transfer of glucose oxidase (GOD) for rapid, highly sensitive and cost-effective determination of BDE-15 based on the blocking effect.

Graphene oxide/gold nanoparticle/graphite fiber microelectrodes for directing electron transfer of glucose oxidase and glucose detection

A promising electrochemical sensor is investigated using graphene oxide (GO)/gold nanoparticle (AuNP)-modified graphite electrodes to enhance charge transport in electrochemical biosensors and increase the sensitivity for glucose detection. An efficient charge transfer pathway is formed by interconnected GO nanosheets and AuNP along the graphite fiber (GF) electrode (GFE). The positive GO can adsorb glucose oxidase (GOD) by electrostatic attraction. The detected response current of the sensor is linearly related to the glucose concentration within a detection limit of 1.2 μM. Furthermore, this glucose sensor has high stability, good reproducibility and excellent selectivity for various oxidizable molecules such as dopamine (DA), uric acid (UA), ascorbic acid (AA) and other molecules causing chaff interference (fructose, lactose and galactose). It is worth noting that this work shows a new method using covalent bonds and self-assembly on the surface of GF for fabricating excellent electrochemical glucose biosensors.

Graphene Oxide/Gold Nanoparticle/Graphite Fiber Microelectrodes for Directing Electron Transfer of Glucose Oxidase and Glucose Detection

Graphene Oxide/Gold Nanoparticle/Graphite Fiber Microelectrodes for Directing Electron Transfer of Glucose Oxidase and Glucose Detection

A Glucose Biosensor Based on Direct Electron Transfer of Glucose Oxidase on PEDOT Modified Microelectrode

Implantable glucose biosensor based on poly (3,4-ethylenedioxythiophene) (PEDOT) modified carbon fiber (CF) microelectrode was fabricated for the first time. Main appeal of this work was the immobilization of glucose oxidase (GOx) on PEDOT film by electrostatic interaction, which resulted in the direct electron transfer (DET) between the active sites of enzyme and electrode in the help of PEDOT. The sensor exhibited selective response to glucose in the presence of some common interference. The biosensor operates at a low potential of −0.65 V vs Ag/AgCl, and the amperometric response was linear over range from 0.5 mM to 15 mM for glucose with a sensitivity of 8.5 μA·cm−2·mM−1. The Michaelis-Menten constant was calculated as 6.5 mM, and the sensor retain 81.3% sensitivity after 60 d storage. Moreover, the extremely simple process of DET construction could be potentially extended for the mass production.

Direct Electron Transfer of Glucose Oxidase in Carbon Paper for Biofuel Cells and Biosensors

Direct Electron Transfer of Glucose Oxidase in Carbon Paper for Biofuel Cells and Biosensors

Enhanced direct electron transfer of glucose oxidase based on gold nanoprism and its application in biosensing

Gold nanoprism (AuNP) was used for immobilization of glucose oxidase (GOD), and the direct electrochemistry of GOD–AuNP–chitosan modified GCE and glucose biosensing were studied. Transmission electron microscopy, UV–vis spectroscopy and electrochemical impendence spectroscopy were employed to confirm the morphology and film modification changes of the prepared biosensor. Results showed that the AuNP can provide a favorable and biocompatible microenvironment for facilitating the direct electron transfer between proteins and electrode surface. It was found that the special structure of gold nanoprism exhibited enhanced performances in direct electron transfer of GOD and glucose sensing. The adsorbed GOD displayed an apparent electron transfer rate constant (ks) of 24.92s−1. The constructed biosensor exhibited a good response to glucose with linear range from 0.05 to 1.2mM (R2=0.9975), low detection limit of 0.01mM and high sensitivity of 11.83μAmM−1cm−2. The proposed biosensor offers an alternative method for the determination of glucose in real samples and has potential applications in the fabrication of other biosensors with redox proteins.

Achievement and assessment of direct electron transfer of glucose oxidase in electrochemical biosensing using carbon nanotubes, graphene, and their nanocomposites

Carbon nanotubes, graphenes, and their hybridized composites with nanoparticles have been attempted to establish a direct electrical communication between the recognition biomolecule and its underlying electrode surface. This review (with 133 refs.) focuses on advances, strategies and technical challenges in the development of reagentless electrochemical biosensors for glucose with enhanced detection sensitivity, selectivity, and simplicity. Specifically, the review commences with a discussion of the relevance of direct electron transfer (DET) in biosensing together with the fundamental of electro-enzymology and kinetics. General aspects of glucose oxidase (GOx), the most popular enzyme with a flavin cofactor, are discussed in view of its historical and important role in the development of electrical biosensors for blood glucose. The next section assesses DET of GOx based on the Marcus theory and the Laviron formalism. The reorganizational energy of the Marcus model and the overpotential play an important role in reaction kinetics and affect the rate of electron transfer significantly. The presence of nanomaterials, particularly for graphene oxide, decreases the electron transfer distance between the enzyme redox center and the underlying electrode surface well beyond 15 A. The improper Marcus-Hush-Chidsey integral is now simplified to estimate the rate of electron transfer with very good accuracy. Critiques, technical challenges, and future possibilities of glucose electrodes with respect to DET are also presented and discussed.

A glassy carbon electrode modified with a composite consisting of reduced graphene oxide, zinc oxide and silver nanoparticles in a chitosan matrix for studying the direct electron transfer of glucose oxidase and for enzymatic sensing of glucose

The authors describe the fabrication of a nanocomposite consisting of reduced graphene oxide, zinc oxide and silver nanoparticles by microwave-assisted synthesis. The composite was further reduced in-situ with hydrazine hydrate and then placed, along with the enzyme glucose oxidase, on a glassy carbon electrode. The synergistic effect of the materials employed in the nanocomposite result in excellent electrocatalytic activity. The Michaelis-Menten constant of the adsorbed GOx is 0.25 mM, implying a remarkable affinity of the GOx for glucose. The amperometric response of the modified GCE is linearly proportional to the concentration of glucose in 0.1 to 12.0 mM concentration range, and the detection limit is 10.6 µM. The biosensor is highly selective, well reproducible and stable.

Electrochemically Functionalized Seamless Three-Dimensional Graphene-Carbon Nanotube Hybrid for Direct Electron Transfer of Glucose Oxidase and Bioelectrocatalysis.

Three-dimensional seamless chemical vapor deposition (CVD) grown graphene-carbon nanotubes (G-CNT) hybrid film has been studied for its potential in achieving direct electron transfer (DET) of glucose oxidase (GOx) and its bioelectrocatalytic activity in glucose detection. A two-step CVD method was employed for the synthesis of seamless G-CNT hybrid film where CNTs are grown on already grown graphene film on copper foil using iron as a catalyst. Physical characterization using SEM and TEM show uniform dense coverage of multiwall carbon nanotubes (MWCNT) grown directly on graphene with seamless contacts. The G-CNT hybrid film was electrochemically modified to introduce oxygenated functional groups for DET favorable immobilization of GOx. Pristine and electrochemically functionalized G-CNT film was characterized by electrochemical impedance spectroscopy (EIS), cyclic voltammetry, X-ray photoelectron-spectroscopy, and Raman spectroscopy. The DET between GOx and electrochemically oxidized G-CNT electrode was studied using cyclic voltammetry which showed a pair of well-defined and quasi-reversible redox peaks with a formal potential of -459 mV at pH 7 corresponding to the redox site of GOx. The constructed electrode detected glucose concentration over the clinically relevant range of 2-8 mM with the highest sensitivity of 19.31 μA/mM/cm(2) compared to reported composite hybrid electrodes of graphene oxide and CNTs. Electrochemically functionalized CVD grown seamless G-CNT structure used in this work has potential to be used for development of artificial mediatorless redox enzyme based biosensors and biofuel cells.

Interfacial electron transfer of glucose oxidase on poly(glutamic acid)-modified glassy carbon electrode and glucose sensing

The interfacial electron transfer of glucose oxidase (GOx) on a poly(glutamic acid)-modified glassy carbon electrode (PGA/GCE) was investigated. The redox peaks measured for GOx and flavin adenine dinucleotide (FAD) are similar, and the anodic peak of GOx does not increase in the presence of glucose in a mediator-free solution. These indicate that the electroactivity of GOx is not the direct electron transfer (DET) between GOx and PGA/GCE and that the observed electroactivity of GOx is ascribed to free FAD that is released from GOx. However, efficient electron transfer occurred if an appropriate mediator was placed in solution, suggesting that GOx is active. The PGA/GCE-based biosensor showed wide linear response in the range of 0.5–5.5 mM with a low detection limit of 0.12 mM and high sensitivity and selectivity for measuring glucose.

Direct Electron Transfer of Glucose Oxidase and Electrocatalysis of Glucose Based on Gold Nanoparticles/Electroactivated Graphite Nanocomposite

Direct Electron Transfer of Glucose Oxidase and Electrocatalysis of Glucose Based on Gold Nanoparticles/Electroactivated Graphite Nanocomposite

A glucose biosensor based on partially unzipped carbon nanotubes

An amperometric glucose biosensor based on direct electron transfer of glucose oxidase (GOD) self-assembled on the surface of partially unzipped carbon nanotubes (PUCNTs) modified glassy carbon electrode (GCE) has been successfully fabricated. PUCNTs were synthesized via a facile chemical oxidative etching CNTs and used as a novel immobilization matrix for GOD. The cyclic voltammetric result of the PUCNT/GOD/GCE showed a pair of well-defined and quasi-reversible redox peaks with a formal potential of −0.470V and a peak to peak separation of 37mV, revealing that the fast direct electron transfer between GOD and the electrode has been achieved. It is notable that the glucose determination has been achieved in mediator-free condition. The developed biosensor displayed satisfactory analytical performance toward glucose including high sensitivity (19.50μAmM−1cm−2), low apparent Michaelis–Menten (5.09mM), a wide linear range of 0–17mM, and also preventing the interference from ascorbic acid, uric acid and dopamine usually coexisting with glucose in human blood. In addition, the biosensor acquired excellent storage stabilities. This facile, fast, environment-friendly and economical preparation strategy of PUCNT–GOD may provide a new platform for the fabrication of biocompatible glucose biosensors and other types of biosensors.

Direct electron transfer of glucose oxidase and dual hydrogen peroxide and glucose detection based on water-dispersible carbon nanotubes derivative

A water-dispersible multi-walled carbon nanotubes (MWCNTs) derivative, MWCNTs-1-one-dihydroxypyridine (MWCNTs-Py) was synthesis via Friedel–Crafts chemical acylation. Raman spectra demonstrated the conjugated level of MWCNTs-Py was retained after this chemical modification. MWCNTs-Py showed dual hydrogen peroxide (H2O2) and glucose detections without mutual interference by adjusting pH value. It was sensitive to H2O2 in acidic solution and displayed the high performances of sensitivity, linear range, response time and stability; meanwhile it did not respond to H2O2 in neutral solution. In addition, this positively charged MWCNTs-Py could adsorb glucose oxidase (GOD) by electrostatic attraction. MWCNTs-Py-GOD/GC electrode showed the direct electron transfer (DET) of GOD with a pair of well-defined redox peaks, attesting the bioactivity of GOD was retained due to the non-destroyed immobilization. The high surface coverage of active GOD (3.5×10−9molcm−2) resulted in exhibiting a good electrocatalytic activity toward glucose. This glucose sensor showed high sensitivity (68.1μAmM−1cm−2) in a linear range from 3μM to 7mM in neutral buffer solution. The proposed sensor could distinguish H2O2 and glucose, thus owning high selectivity and reliability.

A polyaniline microtube platform for direct electron transfer of glucose oxidase and biosensing applications.

Polyaniline (PANI) microtubes are becoming greatly significant electrochemical materials owing to their large geometric surface area, high conductivity and ideal electrocatalytic activity. In this work, using glucose oxidase (GOx) as a model redox protein, a direct electron transfer strategy based on PANI microtubes was developed for fabricating sensitive biosensors. There is a strong electrostatic interaction between the positively charged PANI microtubes and negatively charged GOx, which promotes the immobilization of GOx on the PANI microtube surface. The immobilized GOx displayed a pair of well-defined quasi-reversible redox peaks with a potential of -0.39 V (vs. SCE) and an ideal electron transfer rate constant (ks) of 3.0 s-1 in PBS solution (0.1 M, pH = 5.5) on the PANI microtubes instead of a bare glass carbon electrode (GCE). The amperometric response of the GOx/PANI microtube modified electrode was linearly proportional to the concentration of glucose in the range of 4.0 μM to 0.80 mM. The glucose detection limit was 0.8 μM at a signal-to-noise ratio of 3, which was better than those reported for the GOx/PANI film (1 mM) and GOx/PANI nanowire (50 μM). The advantages might be attributed to the PANI microtubes' large geometric surface for carrying enzyme (GOx) and efficient electrocatalytic activity to facilitate the direct electron transfer of GOx, as well as an efficient GOx biocatalyst reaction on the microtube surface. A promising application of PANI microtube-based biosensors was offered.

Spontaneous Deposition of Prussian Blue on Reduced Graphene Oxide – Gold Nanoparticles Composites for the Fabrication of Electrochemical Biosensors

AbstractA reduced graphene oxide‐gold nanoparticles‐Prussian blue (RGO‐AuNPs‐PB) composite was prepared by spontaneous deposition of PB on RGO‐AuNPs surface. The GC/RGO‐AuNPs‐PB modified electrode offered good electrocatalytic activity toward the reduction of hydrogen peroxide, indicating the possible synergistic effects of the RGO‐AuNPs‐PB composite material. Direct electron transfer of glucose oxidase (GOD) can be realized after codeposition of GOD and chitosan (CHIT) coating on GC/RGO‐AuNPs‐PB electrode. The resulting GC/RGO‐AuNPs‐PB/GOD‐CHIT biosensor exhibited an excellent amperometric response to glucose with a sensitivity of 84 mA M−1 cm−2, and a linear range from 13 µM to 2.0 mM at +0.1 V vs. Ag|AgCl reference.

Immobilization of glucose oxidase on graphene and cobalt phthalocyanine composite and its application for the determination of glucose

We described a simple and facile chemical reduction strategy for the preparation of graphene (GR)-cobalt phthalocyanine (CoPc) composite and explored it for the enzymatic determination of glucose. CoPc is an active mediator and electrocatalysts for the immobilization of GOx and determination of glucose. However, it is not stable on the electrode surface and also suffers from lack of conductivity. Here, we have employed GR as the suitable support to stabilize CoPc through simple chemical reduction method and the resulting composite has been used for the glucose biosensor application. Scanning electron microscopy, X-ray diffraction and Energy-dispersive X-ray spectroscopy studies confirmed the successful formation of composite. Direct electron transfer of glucose oxidase (GOx) was observed with well defined redox peaks at the formal potential of −0.44V. The amount of electroactive GOx (Г) and electron transfer rate constant (ks) were calculated to be 3.77×10−10molcm−2 and 3.57s−1, respectively. The fabricated amperometric biosensor detects glucose in wide linear concentration range from 10μM to 14.8mM with high sensitivity of 5.09μAmM−1cm−2. The sensor offered very low detection limit (LOD) of 1.6μM. In addition, practical feasibility of the sensor has been explored in screen printing carbon electrode with accurate determination of glucose present in human blood serum and urine samples. Furthermore, the sensor exhibited appreciable stability, repeatability and reproducibility results.

Immobilization of Glucose Oxidase on 4-(pyrrole-1-yl) Benzoic Acid Functionalized Carbon Nanotubes for Direct Electrochemistry and Glucose Sensing

In recent years, carbon nanotubes (CNT) have gained considerable attention, because of their remarkable electronic and mechanical properties, which have made them extremely attractive for a wide range of sensing applications from structural materials to nanoelectronic components. The ability of CNT-modified electrodes to promote electron transfer reactions has been documented in connection with important biomolecules [1]. Our goal is to explore new applications of CNT as an electrode material in facilitating the electron transfer between enzyme molecule and electrode in the bioelectrocatalytic system for glucose oxidation that is of potential utility for bioelectronic devices such as biosensors and biofuel cells.Our research focuses on the direct electrochemical performance of glucose oxidase (GOx) immobilized on 4-(pyrrole-1-yl) benzoic acid (PyBA) modified multi-walled carbon nanotubes (CNTs). GOx is a homodimer containing two tightly bound flavin adenine dinucleotide (FAD) redox centers embedded deeply in the enzyme [2]. Modification of carbon nanostructures allow to obtain thin and organized films, causing a rapid and effective transfer of electrons between the active center of the biocatalyst (GOx) and the electrode surface. The presence of PyBA in our composite film significantly improves their stability and introduces new functional groups that have great importance in the enzyme immobilization process onto the CNTs-modified electrode [3].In this work stable immobilization and direct electron transfer of glucose oxidase were achieved on the composite film modified glassy carbon electrode. The resulting electrode gave a well-defined redox peaks with a formal potential of about −440 mV (vs. Ag/AgCl) in 0.1 phosphate buffer solution pH=7.0. The electron transfer rate constant was estimated to be 3.15 s-1, due to the combined contribution of CNTs/PyBA and GOx. Furthermore, the method for detecting of glucose was proposed based on the decrease of oxygen caused by the enzyme-catalyzed reaction between GOx and glucose. The low calculated apparent Michaelis–Menten constant (KM app) was 10.2 mM, implying the high enzymatic activity and affinity of immobilized enzyme for glucose. It can reasonably be expected that this observation might hold true for other noble carbon nanostructure-electroactive protein systems, providing a promising platform for the development of biosensors and biofuel cells.

Investigation of the optimal weight contents of reduced graphene oxide–gold nanoparticles composites and theirs application in electrochemical biosensors

Graphene, as a single-atom-thick carbon material, is considered an ideal platform for designing composite nanomaterials for high-performance electrochemical or electrocatalytic devices. Reduced graphene oxide–gold nanoparticles composites were prepared by depositing gold nanoparticles (AuNPs) on the surface of reduced graphene oxide (RGO) with different RGO-to-AuNPs weight ratios. The resulting composite materials were characterized morphologically and optically by scanning electron microscopy (SEM) and UV–visible absorption spectroscopy. Cyclic voltammetry and amperometric measurements were employed to investigate the electrocatalytic effect of different composites toward the reduction of hydrogen peroxide. Experimental results demonstrated that RGO–AuNPs composites displayed high stability and catalytic effect for the analysis of hydrogen peroxide, demonstrating the possible synergistic effects of the RGO–AuNPs composite materials. Additionally, direct electron transfer of glucose oxidase (GOD) was achieved after codeposition of GOD and chitosan (CHIT). The glassy carbon electrode modified with RGO–AuNPs/CHIT–GOD material exhibited an excellent catalytic effect for glucose detection with a sensitivity of 34mAM−1cm−2 at a detection potential of −0.3V vs. Ag|AgCl reference.