Direct Electrochemistry of Glucose Oxidase at Reduced Graphene Oxide and β‐Cyclodextrin Composite Modified Electrode and Application for Glucose Biosensing

Abstract

1IntroductionOver the past few decades,t he studies on direct electron transfero fr edox activep roteins or enzymes have received much interesto wing to their application in different fieldsi ncluding biosensors and biofuel cells [1][2][3].I n electrochemical analysis,t he determination of glucose is very important in different fields especially in the clinical diagnosis.D iabetes mellitus is them ost common endocrine disorder,w hich leadst om ajor health problems.T he World Health Organization (WHO) has reported that an approximately 171 million people are affectedb yd iabetes and it may increase to 366 million by 2030 [2].T he higher and lower blood glucose level from the normal glucose range (4.4-6.6 mM) always result in metabolic disorders. Glucose oxidase( GOx) is widely used for the construction of glucose biosensors due to its high selectivity towards glucose [4].H owever, the immobilization of GOx on the conventional electrodes is quite difficult,s ince the redox active sites of GOx is deeply buriedi nside and covered by at hick protein layer. Hence,d ifferent nanomaterials such as carbonn anomaterials,m etal nanoparticles, metal oxides,c onducting polymers and so on [4-10] have been used for immobilization to achieve directe lectrochemistry of GOx, Carbon nanotubes are well known carbon nanomaterials which have been used for constructiono fg lucose biosensors owing to its unique structural properties.C arbon nanotubes have also integrated with conductingp olymers, metal oxides,c arbon nanomaterials and metaln anoparticles have also been used for construction of glucoseb iosensor based on the direct electrochemistry of GOx [ 5]. Recently,r educed graphene oxide (RGO) or graphene has been used as an ovel electrode materialf or different potential applications including constructiono fg lucose biosensors [7].R GO is a2 Dc arbon nanomaterial from graphitic family and has shown excellent electrochemical properties compared to other graphitic carbon nanomaterials [ 11,12].H owever, the direct immobilization of redox proteins on pristineR GO is quite difficult due to van der Waals interactions betweeni ndividual RGO sheets [13][14][15].T oo vercome this problem, different approaches or modifiers have been used with RGO to immobilize the GOxa nd enhance the biocompatibility of RGO.Them odifierss uch as nafion, sodiumd odecyl sulfate and chitosan have been used with RGO to enhance the biocompatibilityo ft he RGO [16][17][18].T he composite of RGOw ith carbon nanomaterials,m etal nanoparticles, metal oxides and conducting polymers have also been used for the immobilization matrix of GOx [19][20][21][22][23].R eAbstract:Asimple glucose biosensor has been developed based on direct electrochemistry of glucose oxidase (GOx) immobilizedo nt he reducedg raphene oxide (RGO) and b-cyclodextrin (CD)c omposite.Awell-defined redoxc oupleo fG Ox appears with af ormal potential of~À0.459 VatR GO/CD composite.Ah eterogeneous electron transfer rate constant (K s )h as been calculated for GOx at RGO/CD as 3.8 s À1.T he fabricated...

Graphene Oxide-Based Biosensors

“…Thus, the electrostatic interaction between ZnO and GOD (with an isoelectric point at 4.2) can occur. Chen et al [11] prepared ZnO-microflowers on reduced graphene oxide (RGO) modified GCE by using simple electrodeposition (Figure 5). This positively charged ZnO/RGO composite self-assembled with negatively charged GOD and fabricated an RGO/ZnO/GOD biosensor.…”

ZnO nanostructures in enzyme biosensors

“…ZnO nanocomposites containing these nanomaterials have also been applied in biosensors [11,13,14,[66][67][68][69][70][71][72][73][74][75][76]. Graphene/ ZnO NPs hybrids (Fig.…”

“…The resulting nanohybrids exhibited antibacterial activity against E.coli, a gram negative bacteria, suggesting their potential in biosensing and bioengineering. ZnO NPs [14,72,73], ZnO micro-sponges [74], ZnO micro-flowers [75], and ZnO trigonal/tetragonal pyramids [76] were electrochemically deposited on multiwa lled carbon nanotubes (MWCNTs) [14,72−74] and reduced graphene oxide [75,76], respectively. The resulting biosensors exhibited good electrocatalytic activity with fast electron transfer towards glucose.…”

Electrochemically Prepared Unzipped Single Walled Carbon Nanotubes-MnO2 Nanostructure Composites for Hydrogen Peroxide and Glucose Sensing

“…For example, Yaojuan et al investigated gold nanoparticle (AuNP)-graphene nanocomposites as a new electrode material synthesized by electrochemical deposition of Au-NPs on graphene sheets [30]. Selvakumar et al demonstrated the glucose biosensing properties of a direct growth of glucose oxidase (GOx) on reduced graphene oxide/β-Cyclodextrin composite modified electrode for glucose monitoring [31]. Qinglin et al fabricated glassy carbon electrode with graphene-carbon nanotube-nafion/gold-platinum alloy nanoparticles [32].…”