Electrocatalytic Oxidation of Glucose by the Glucose Oxidase Immobilized in Graphene‐Au‐Nafion Biocomposite

Abstract

Graphene was successfully prepared and well separated to individual sheets by introducing ÀSO 3 À . XRD and TEM were employed to characterize the graphene. UV-visible absorption spectra indicated that glucose oxidase (GOx) could keep bioactivity well in the graphene-Au biocomposite. To construct a novel glucose biosensor, graphene, Au and GOx were co-immobilized in Nafion to further modify a glassy carbon electrode (GCE). Electrochemical measurements were carried out to investigate the catalytic performance of the proposed biosensor. Cyclic voltammograms (CV) showed the biosensor had a typical catalytic oxidation response to glucose. At the applied potential þ 0.4 V, the biosensor responded rapidly upon the addition of glucose and reached the steady state current in 5 s, with the present of hydroquinone. The linear range is from 15 mM to 5.8 mM, with a detection limit 5 mM (based on the S/N ¼ 3). The Michaelis-Menten constant was calculated to be 4.4 mM according to Lineweaver -Burk equation. In addition, the biosensor exhibits good reproducibility and long-term stability. Such impressive properties could be ascribed to the synergistic effect of graphene-Au integration and good biocompatibility of the hybrid material.Keywords: Glucose biosensor, Graphene, Au nanoparticles, Electrocatalytic oxidation, Synergistic effect, Biosensors, NanoparticlesThe determination of glucose is very important in industry [1], clinical diagnostics [2], environmental monitoring [3] and food processing [4]. Especially for the patients who suffer from diabetes, the monitoring of blood glucose concentration must be taken momently. For the purpose to design highly sensitive, selective and stable biosensor, numerous materials have been attempted to modify electrode, including metal nanoparticles [5,6], conducting polymer [7,8], semiconductor quantum dots [9] and carbon nanotube (CNT) [10 -12]. Among them, CNT has been utilized most widely due to a few unique properties it possesses, such as excellent mechanical strength, high surface area, good chemical stability and outstanding electrical conductivity [13]. However, to most CNT synthesis methods, metal catalyst residues can not be completely removed even after iterative purification, leading to some unexpected results [14,15]. In addition, CNT is highcost and large scale synthesis-prohibitive. Therefore, there is always a demand of finding an affordable alternative to CNT for sensors fabrication.Graphene, which was characterized as the thinnest material in our universe [16], has attracted more and more attention since it was firstly obtained by a scotch tape method in laboratory [17]. Graphene is the name given to a flat monolayer of carbon atoms tightly packed into a twodimensional (2D) honeycomb lattice, and is a basic building block for graphitic materials of all other dimensionalities [18]. The unique properties of graphene involve of high surface area-to-volume ratio, excellent thermal conductivity and mechanical stiffness. Most prominently, carriers in an ideal graphene she...

Simultaneous determination of uric acid and dopamine using a carbon fiber electrode modified by layer-by-layer assembly of graphene and gold nanoparticles

“…Graphene (GE), a one-atom-thick sp 2 -bonded carbon sheet, has attracted tremendous attention in recent years due to its large amount of edge-plan-like defects and large specific surface area [20][21][22]. The elusive two-dimensional structure of GE contributes to numerous unique electronic properties, such as the quantum Hall effect and transport via relativistic Dirac fermions [23,24], making GE possess high electron conductivity and good biocompatibility. The combination of GE and gold nanoparticles can increase electrode surface and enhance optical, electronic, and catalytic properties.…”

“…The combination of GE and gold nanoparticles can increase electrode surface and enhance optical, electronic, and catalytic properties. Moreover, GE and gold nanoparticles offer synergistic effects in their composite electrocatalytic applications [14,24]. Li et al [25] developed GE and gold nanoparticles modified electrodes which can selectively determine DA with a high detection limit (1.86 μM).…”

Amperometric Glucose Biosensor Based on Integration of Glucose Oxidase with Palladium Nanoparticles/Reduced Graphene Oxide Nanocomposite

“…Especially, amperometric biosensor based on glucose oxidase (GOD) is extremely popular due to its simplicity, reliability, low cost and very stable activity [6][7][8][9]. In this type, glucose level is indirectly monitored by measurement of current associated with the electrochemical detection of hydrogen peroxide produced during the enzymatic reaction in which glucose is oxidized by oxygen with the aid of GOD.…”

Fabrication of Graphene Coated Carbon Fiber Microelectrode for Highly Sensitive Detection Application

“…[10][11][12] Here, dopamine was used as a model assay to reveal the characterization of G-CFM. Figure 7A shows the voltammograms of 0.5 mM DA at CFM and G-CFM in 0.1 M pH 7.0 phosphate buffer solution (PBS).…”

“…[9][10][11] Previous studies have shown that electrochemistry permits CFs to conduct in vitro determination of dopamine (DA) and is also a possible "tool" for their in vivo determination usage. 10 At present, accompanied by the development of nanotechnology and expansion of electrode modification technology, carbon fiber microelectrode (CFMs) biosensors have seen rapid development and have thus expanded the applications of carbon-based fibers. Some groups have studied DA using carbon fiber microelectrodes modified by carbon nanomaterials, such as single-walled or multiwalled carbon nanotubes.…”