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Electrochimica Acta 56 (2011) 1239–1245

Contents lists available at ScienceDirect

Electrochimica Acta

journa l homepage: www.e lsev ier .com/ locate /e lec tac ta

lectrochemical sensing based on graphene oxide/Prussian blue hybrid filmodified electrode

ao Zhang, Xiumei Sun, Longzhang Zhu, Hebai Shen, Nengqin Jia ∗

epartment of Chemistry, College of Life and Environmental Sciences, Shanghai Normal University, 100 Guilin Road, Shanghai 200234, China

r t i c l e i n f o

rticle history:eceived 25 August 2010eceived in revised form 1 November 2010ccepted 6 November 2010vailable online 13 November 2010

eywords:raphene oxide

a b s t r a c t

A novel graphene oxide (GO)/Prussian blue (PB) hybrid film was constructed by electropolymerizingPrussian blue onto the GO modified glassy carbon electrode, and its electrochemical behaviors werestudied. Raman spectra were used to investigate the successful formation of the GO/PB hybrid film.Electrochemical experiments showed that the graphene oxide greatly enhanced electrochemical reac-tivity of the PB. Moreover, a much higher Prussian blue (PB) loading (6.388 × 10−8 mol cm−2) is obtainedas compared to the bare glass carbon surface (3.204 × 10−9 mol cm−2). The GO/PB hybrid film modifiedelectrode was used for the sensitive detection of hydrogen peroxide. The sensor exhibited a wide linearity

−6 −3 −7

russian blueybrid filmydrogen peroxidelectrocatalysis

range from 5.0 × 10 to 1.2 × 10 M with a detection limit of 1.22 × 10 M (S/N = 3), high sensitivity of408.7 �A mM−1 cm−2 and good reproducibility. Furthermore, with glucose oxidase (GOD) as a model, theGO/PB/GOD/chitosan composite-modified electrode was also constructed.

The resulting biosensor exhibited good amperometric response to glucose with linear range from 0.1to 13.5 mM at 0.1 V, good reproducibility and detection limit of 3.43 × 10−7 M (S/N = 3). In addition, the

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biosensor presented highmodified electrode may h

. Introduction

Graphene has emerged as a strictly two-dimensional (2D) andne-atom-thick sheet material with interesting physical properties1,2]. The unique nanostructure and properties of graphene make itpromising candidate for fundamental study as well as for poten-

ial device applications such as field-effect transistors, gas sensors,lectromechanical resonators [3–6]. In the past decades, severalorms of carbon materials (e.g. ordered mesoporous carbon [7,8],arbon nanofiber [9], carbon nanotube [10,11]) have been studiedo immobilize redox enzymes and used for developing enzyme-ased electrochemical devices. Graphene is an ideal material forlectrochemistry [12] because of its very large 2D electrical con-uctivity, large surface area and low cost. Based on the previouseports, graphene-based electrodes have been applied in the elec-rochemical stripping determination of cadmium [13], the selectiveetection of dopamine [14] and a platform for electrocatalytic oxi-ation of hydrazine in alkaline media [15].

More recently, it is attractive to develop graphene-basedanocomposite films as enhanced sensing platform for construct-

ng electrochemical sensors and biosensors, because these kindsf nanocomposite films may generate synergy on electrocat-

∗ Corresponding author. Tel.: +86 21 64321045; fax: +86 21 64322511.E-mail address: nqjia@shnu.edu.cn (N. Jia).

013-4686/$ – see front matter © 2010 Elsevier Ltd. All rights reserved.oi:10.1016/j.electacta.2010.11.011

ctivity and long-term stability. Therefore, the PB/GO hybrid films-basedreat promise for electrochemical sensing and biosensing applications.

© 2010 Elsevier Ltd. All rights reserved.

alytic activity and thus enhance the sensitivity of the sensors.Cai et al. have reported a novel electrochemical approach fordetection of the extracellular oxygen released from human ery-throcytes based on graphene sheets integrated with laccase andABTS [16]. Further, Niu and co-workers indicated the PVP-protectedgraphene/polyethylenimine-functionalized ionic liquid nanocom-posite exhibits good electrocatalysis toward the reduction of H2O2,and further achieved the direct electron transfer of GOD [17].

On the other hand, H2O2 is an essential mediator in food, phar-maceutical, clinical, industrial, and environmental analyses as well;therefore, the accurate determination of H2O2 is of great impor-tance [18]. Prussian blue (PB) has been denoted as an “artificialperoxidase” because of its rapid catalytic rate toward reductionof hydrogen peroxide at low overpotential [19]. PB or PB-basedcomposites, as attractive alternative electrocatalysts for H2O2detection, have been widely used in the biosensor construction[20,21], which can exclude the interference from the coexistingsubstances such as ascorbic acid (AA), acetaminophen (AP), and uricacid (UA) [22]. Carbon nanotube/PB nanocomposites have also beeninvestigated extensively in recent years [23,24]. Given the econom-ical cost and facile preparation of GO, exploring facile method for

the synthesis of GO/PB hybrid film with excellent electrocatalyticproperties is still significant.

In this work, in order to combine the advantages of the GOnanosheets (e.g. unique 2D nanostructure, enlarged active sur-face area, its potential low manufacturing cost) together with the

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nique features of PB, a novel GO/PB hybrid film was constructedn this research by electropolymerizing Prussian blue onto the GO

odified glassy carbon electrode (GCE) and then used for electro-hemical sensing applications. By comparing the electrochemicalerformance of GO/PB with that of the PB/GCE, we revealed thatO/PB hybrid film exhibited much better electrochemical and elec-

rocatalytic activities to H2O2, which could be attributed to theynergistic effects of GO and PB. Furthermore, as an example, weommunicated an application of GO/PB hybrid film in the fabri-ation of an electrochemical glucose biosensor, which displayedavorable biosensing perfomances. The obtained results showedhe GO/PB nanocomposite film could be used as enhanced sensinglatform for developing novel types of highly sensitive and stablelectrochemical sensors.

. Experimental

.1. Reagents

Graphite powder (spectrum pure), potassium ferricyanideK3Fe(CN)6), potassium chloride (KCl), ferric chloride (FeCl3·6H2O)nd hydrogen peroxide solution (30 wt%) were obtained fromhanghai Chemical Reagent Co. (China). Glucose oxidase (GOD, EC.1.3.4, Type X-S, lyophilized powder, 117 U mg−1, from Aspergillusiger), d-(+)-glucose (≥99.5%) and chitosan were obtained fromigma.

Glucose stock solutions (0.1 M) were prepared and allowed toutarotate at room temperature for 24 h before measurements. All

ther chemicals were of analytical grade and all the solutions wererepared with doubly distilled water. In the experiments, phos-hate buffered saline (0.01 M KH2PO4/K2HPO4, pH 6.0) with 0.1 MCl was used as the supporting electrolyte.

.2. Apparatus and measurements

JEOL 2100 transition electronic microscopy was used for trans-ission electron microscopy (TEM) analysis. Scanning electronicroscopy (SEM) image was obtained using a JSM-840 field

mission SEM system (Japan). Powder X-ray diffraction (XRD)easurements were performed on Rigaku D/max-2000 X-rayiffraction with Cu Ka radiation (� = 1.5406). Atomic force micro-

copic (AFM) images were recorded with a Nanoscope IIIa scanningrobe microscope (Digital Instruments) using a tapping mode.aman spectra were measured on Super Labram II Confocal micro-copic Raman spectrometer Instrument (Dilor, France).

All electrochemical experiments were carried out with CHI 660Blectrochemical workstation (CH Instruments, Shanghai, China).he three-electrode system contained a bare or PB/GO modifiedlectrode as the working electrode, a saturated calomel electrodend a platinum wire electrode as reference electrode and counterlectrode, respectively.

.3. Synthesis of graphene oxide

Graphene oxide (GO) was synthesized directly from graphitey a modified Hummers method [25,26]. Generally, 1 g graphiteas ground with 50 g NaCl for 10 min. NaCl was then dissolved

nd removed by filtration with water. The remaining graphite wastirred in 23 mL of 98% H2SO4 for 8 h. KMnO4 (3 g) was graduallydded while keeping the temperature less than 20 ◦C. The mixture

as then stirred at 80 ◦C for 45 min. Next, water (46 mL) was added

nd the mixture was heated at 105 ◦C for 30 min. The reaction waserminated by addition of distilled water (140 mL) and 30% H2O2olution (10 mL). The resulting mixture was washed by repeatedentrifugation and filtration, first with 5% HCl aqueous solution and

cta 56 (2011) 1239–1245

then distilled water. Finally, the graphene oxide (GO) product wasobtained after dried in vacuum.

2.4. Preparation of GO/PB and PB/GCE modified electrode

The glassy carbon electrodes (GCE, 3 mm in diameter) werepolished to a mirror-like with 0.3 and 0.05 �m alumina slurry,then sonicated in nitric acid (1:1), ethanol and doubly distilledwater in turn. 1.0 mg graphene oxide was dispersed in 1 mLdimethy sulphoxide (DMSO) to form a homogenous mixture. 5 �Lof 1.0 mg mL−1 mixtures were dropped on the surface of GCE anddried under an infrared lamp. Cyclic voltammetry (CV) method wasperformed to deposit Prussian blue (PB) film on the surface of GOmodified GCE and the bare GCE. The electropolymerization of PBwas achieved by immersing the electrode in a unstirred fresh solu-tion containing 5 mM K3[Fe(CN)6], 5 mM FeCl3, 0.1 M HCl, followingby a cyclic scan in a potential range of 0 to +0.5 V at 20 mV s−1 for 20cycles. After electropolymerization, the electrodes were thoroughlywashed with double distilled water, then transferred into a sup-porting electrolyte solution (0.01 M pH 6.0 KH2PO4/K2HPO4 buffersolution containing 0.1 M KCl) and electrochemically activated bycycling between −0.2 and +0.5 V at a scan rate of 50 mV s−1. Finally,the electrodes were rinsed with double-distilled water and driedin air.

2.5. Fabrication of the GO/PB/GOD/chitosan-modified electrode

5.0 �L of the glucose oxidase (GOD) and 3.0 �L chitosan solu-tions were dropped onto GO/PB modified electrode and allowedto dry in ambient air for 12 h to obtain a GO/PB/GOD/chitosan-modified electrode. The same procedures were prepared on thePB/GOD/chitosan-modified electrode without GO as comparison.

3. Results and discussion

3.1. Characterization of graphene oxide

The morphologies and the structures of the prepared grapheneoxide were characterized using TEM, SEM, XRD and AFM. It can beobserved that the prepared graphene oxide illustrates the flake-likeshape and layer–layer structure of graphene oxide edges (Fig. 1Aand B). The XRD pattern (Fig. 1C) reveals its characteristic peak at2� = 24.7◦ [27]. From AFM image (Fig. 1D), large graphene oxidesheets are observed. The cross-sectional analysis indicates thethickness of graphene is ca. 0.8 nm, demonstrating the single-sheetnature of graphene oxide is obtained.

3.2. Raman spectra of different modified electrodes

Fig. 2 shows the Raman spectra of GO (a), GO/PB (b) and PB(c). The spectra exhibit the presence of D and G bands, located at1348 cm−1 and 1581 cm−1 (curve a). There is a strong vibrationalband at 2095 cm−1 (curve c), which are most likely caused by thestretching vibration of CN group of PB [28]. The Raman spectrumof the GO/PB composite film (curve b) contains their characteristicpeaks of GO and PB, indicating that PB was deposited on the GOmodified electrode. In the microstructure of PB, the ferric ions arecoordinated to the nitrogen atoms, and the ferrous ions connectstrongly to the carbon atoms of the bridging cyanide ligands [29].

3.3. Electrochemical behavior of GO/PB composite film

Electrochemical properties of GO/PB hybrid film were then stud-ied. As shown in Fig. 3A, the GO/GC modified electrodes did notshow any obvious redox peak. For GO/PB and PB/GC modified elec-trodes, a pair of well-defined redox peaks appeared with E◦ values

Y. Zhang et al. / Electrochimica Acta 56 (2011) 1239–1245 1241

Fig. 1. TEM (A), SEM (B) images, X-ray diffraction pattern (

Fig. 2. Raman spectra of (a) GO, (b) GO/PB and (c) PB.

C) and AFM (D) of graphene oxide (GO) nanosheets.

of near 0.2 V, which is ascribed to the redox process of Prussian blueand Prussian white [30], and the peak current with a peak potentialof ca. 0.20 V is from the redox reaction of the iron ions coordinatedto nitrogen in the group CN [31]. However, the peak current valueat the GO/PB modified electrode is 56.21 �A, about ten times muchlarger than that at the PB/GC modified electrode (6.974 �A). Thisphenomenon may be ascribed that the graphene oxide with largespecific surface area could facilitate more PB polymerizing on theGO.

The CV curves of GO/PB modified GC electrode at various scanrates were also investigated (Fig. 3B). With increasing scan rateboth redox peak currents and peak-to-peak separation increased.The anodic and cathodic peak currents are linearly proportionalto the scan rate ranging from 10 mV s−1 to 100 mV s−1, indicat-ing that the redox process of PB in this composite film was a

reversible and surface-confined process [32,33]. From the inte-gration of the Fe(III) reduction peaks of modified electrodes atdifferent scan rates and according to Faraday’s law Q = nFA� (wheren is the electron-transfer number, F is Faraday’s constant, andA is the geometrical surface area of electrode), the surface cov-

1242 Y. Zhang et al. / Electrochimica Acta 56 (2011) 1239–1245

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ig. 3. (A) Cyclic voltammograms of GO/PB (a), PB/GCE (b) and GO/GCE (c) modioltammograms of GO/PB modified electrode in 0.1 mol/L KCl solution (pH 6.0) atespectively. Inset: plots of peak currents vs. scan rates.

rage of PB onto the GO/GCE electrodes was estimated to be.388 × 10−8 mol cm−2, much larger than that obtained at PB/GClectrode (3.204 × 10−9 mol cm−2). This may be resulted from thatraphene oxide is a strictly two-dimensional material, whosehole volume is exposed to surface adsorbates, maximizing their

ize effect [14].

.4. Electrocatalysis of H2O2 at the GO/PB modified electrode

It is well known that Prussian blue (PB) has certain intrinsiceroxidase activity due to its close similarity with peroxidase, so itan be employed to catalyze the reduction of hydrogen peroxide.o assess the electrocatalytic activity of graphene oxide/Prussianlue hybrid film modified electrode, the electrocatalytic reductionf H2O2 at GO/PB and PB/GC modified electrodes were comparednd are shown in Fig. 4. With the addition of H2O2 into the electro-hemical cell, the reduction peak current increased at about 0.10 V

nd the anodic peak current decreased dramatically, indicating aypical electrocatalytic reduction process of H2O2. Furthermore, theeduction peak current increased with the increasing H2O2 con-entration. The catalytic peak comes from the interaction between

ig. 4. Cyclic voltammograms of GO/PB modified electrode in the absence (a) andresence of 1.10 mmol/L (b), 3.10 mmol/L (c), and 5.00 mmol/L H2O2 (d) in 0.1 mol/LCl 0.01 mol/L KH2PO4/K2HPO4 buffer solution (pH 6.0), scan rate 50 mV s−1. Inset:Vs of PB/GC modified electrode under the same condition.

ectrodes in 0.1 mol/L KCl solution (pH 6.0) at a scan rate of 50 mV s−1. (B) Cyclicus scan rates: 10, 20, 30, 40, 50, 60, 70, 80, 90, 100 mV s−1 (from inner to outer),

PB and H2O2. According to the literature [34], the electrocatalyticmechanism of PB for H2O2 reduction can be expressed as follows:

2K2FeII[FeII(CN)6] + H2O2 + 2H+ = 2KFeIII[Fe(CN)6] + 2H2O + 2K+

(1)

KFeIII[Fe(CN)6] + K+ + e− = K2FeII[FeII(CN)6] (2)

Especially, it can be obviously investigated that with the sameconcentration of H2O2, the electrocatalytic reduction peak cur-rents at the GO/PB modified electrode are much higher than thoseat PB/GCE. Furthermore, the chronoamperometric experiments(Fig. 5A and B) show the sensitivity of the GO/PB modified electrodeand PB/GCE is 408.7 �A mM−1 cm−2 and 56.36 �A mM−1 cm−2,respectively. These results indicated that the GO/PB modified elec-trode exhibited better electrocatalytic activity toward H2O2, whichcould be due to the large deposited amount of PB on the GO mod-ified electrode and high conductivity originated from grapheneoxide. The linear response range of the sensor to H2O2 is from5.0 × 10−6 to 1.2 × 10−3 M with a correlation coefficient of 0.996and the detection limit of 1.22 × 10−7 M (S/N = 3). Its relative stan-dard deviation (RSD) is 1.89% for eight successive determinationsin 2.5 × 10−5 M H2O2 solution. To reveal the possible advantage ofthe present sensors based on GO/PB modified electrode, the perfor-mance of one kind of sensors is compared with the existing sensorsusing Prussian blue prepared from chemically or electrochemicallydeposition, as presented in Table 1. A survey of data in Table 1reveals that this GO/PB-based sensor displays the combination ofhigh sensitivity with good linear range and low limit of detection.

Several common electrochemical interfering species such asascorbic acid (0.2 mM), and uric acid (0.2 mM) did not produceobservable interference in amperometric determination of H2O2.Furthermore, the GO/PB modified electrode could retain the sameelectrochemical behavior upon the continuous CV sweep for 100cycles over the potential range from −0.2 to +0.5 V, and no obviousdecrease in the response to H2O2 as its initial measurement after2 weeks. The experimental results revealed that the GO/PB hybridfilm modified electrode had good reproducibility, selectivity andstability.

3.5. Amperometric response of the biosensor to glucose

Glucose oxidase (GOD) has represented the primary modelenzyme in the development of new sensing materials and meth-

Y. Zhang et al. / Electrochimica Acta 56 (2011) 1239–1245 1243

Fig. 5. . (A) Amperometric response of the GO/PB modified electrode with successive addition of H2O2 to a stirred aqueous buffer solution (0.01 mol/LKH2PO4/K2HPO4 + 0.1 mol/L KCl, pH 6.0). Applied potential: 0.10 V (vs. SCE). Inset: the PB/GC modified electrode at the same condition. (B) Calibration curve of GO/PBmodified electrode as a function of H2O2 concentration.

Table 1Comparison of the GO/PB-based sensor in our work with the existing sensors based on Prussian blue.

Type of electrode Limit of detection/mmol dm−3 Linear range/mmol dm−3 Sensitivity/�A cm−2 mmol−1 dm−3 Reference

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[Ptnano/PCNTs]100 electrode – 0.1PB/MCNT 5.67 × 10−4 0.0GE/PBNPs/Nafion 1.0 × 10−3 2.1GO/PB modified electrode 1.22 × 10−4 5.0

ds [20]. Due to its good electrocatalytical activity of GO/PB hybridlm to H2O2, in our work, a GO/PB composite film-based glucoseiosensor was further developed. Fig. 6A shows the amperomet-ic response of the biosensor to glucose in air-saturated stirringBS. In this experiment, pH value of 6.0 was chosen for the detec-ion of glucose. Because chitosan has a great deal of amino groups,hich can provide a suitable pH microenvironment for GOD [38].

he time required for reaching the 95% steady-state response wasithin 5 s at GO/PB/GOD/chitosan-modified electrode and 15 s at

B/GOD/chitosan-modified electrode, indicating its fast responsef the GO/PB-based biosensor. The linear calibration range forlucose was 0.1–13.5 mM (R = 0.9988, n = 31) (Fig. 6B) and theensitivity of 15.28 �A mM−1 cm−2, which was much higher than

ig. 6. (A) Typical current–time response curves for the successive addition of glucose iotential of 0.1 V (vs. SCE). Inset: the PB/GC modified electrode at the same condition. (B) Concentration.

104.3 [35]153.7 [36]

3 to 0.14 138.6 [37]3 to 1.2 408.7 This work

that reported at a poly(3,4-ethylenedioxythiophene)/PB/MWCNTs-based glucose biosensor in the literature (2.67 �A mM−1 cm−2) [39]and GOD/PB/screen-printed electrode (3.21 ± 0.16 �A mM−1 cm−2)[40]. The detection limit can be estimated for 3.43 × 10−7 M ata signal-to-noise ratio of 3. The linear range up to 13.5 mM wasmuch larger than that obtained at the GOD immobilized on thePB modified electrodes (8.0 mM), glucose biosensors based on GODimmobilized on the PEDOT/PB/MWCNTs (10.0 mM) [39], the immo-bilization of GOD on a PB/chitosan (CS) modified gold electrode

(0.4 mM) [41], GOD at chitosan–gold nanoparticle hybrid film on aPB modified electrode (1.6 mM) [42], GOD immobilized on highlyordered porous anodic alumina (PAA) membrane/PB nanoarray(8.0 mM) [43], GOD/PB/SPE modified electrode (3.0 mM) [40]. It is

n 0.01 M PBS (pH 6.0) at the GO/PB/GOD/chitosan-modified electrode at workingalibration curve of GO/PB/GOD/chitosan-modified electrode as a function of glucose

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ig. 7. Amperometric response to the injection of 0.50 mM glucose, 0.20 mMscorbic acid (AA), 0.20 mM uric acid (UA), 0.20 mM dopamine (DA), 0.20 mM-cysteine, at the GO/PB/GOD/chitosan-modified electrode in 0.1 M KCl (0.01 MH2PO4/K2HPO4, pH 6.0). Applied potential: 0.1 V.

ell known that the diabetic glucose concentration is above 7.0 mM44], which indicates that this biosensor is suitable for its practicalpplication for the determination of human blood sugar concen-ration. The novel biosensor had good reproducibility. The relativetandard deviation (RSD) of the current response to 4.5 mM glucoset 0.1 V was 3.1% for 12 successive measurements, respectively.hese results indicated that the immobilized GOD possesses highnzymatic activity, and the GO/PB/chitosan hybrid film providesavorable microenvironment for GOD at the modified electrode. Thetability of the resulting biosensor was investigated by discontinu-us amperometric measurement after stored in 4 ◦C for weeks andetained about 90% of its initial value to glucose.

.6. Interference study and real samples analysis of the biosensor

The selectivity and anti-interference ability of the biosensor waslso investigated by chronoamperometric method. Fig. 7 shows themperometric response of the biosensor to the consecutive injec-ion of 0.50 mM glucose and 0.20 mM interfering species includingscorbic acid (AA), uric acid (UA), dopamine (DA) and l-cysteine. Itas evident that the influence of interfering species tested on the

lucose response was negligible, indicating a high selectivity of theroposed biosensor.

Human serum samples were assayed to demonstrate the prac-ical use of the proposed biosensor. Its recovery experiments werearried out in human serum samples to demonstrate the applica-ility of the biosensor for real sample analysis. 5 and 10 mM glucoseere added to human serum samples, respectively. The recovery

f the biosensor was 103% (10.29 ± 0.17 mM, n = 8, R.S.D. = 3.1%),nd 96% (14.94 ± 0.23 mM, n = 8, R.S.D. = 3.7%), respectively. Theseesults indicated that it is feasible to apply the proposed biosensoro determine glucose in real samples.

As known, the blood glucose level of normal person ranges fromto 6 mM. So the linear glucose response from 0.1 to 13.5 mM

ased on GO/PB/GOD/chitosan-modified electrode is suitable forts practical application. Moreover, our method can eliminatehe interference of other molecules in blood, which makes it a

romising candidate to determine blood sugar concentration inhe practical clinical analysis. The selectivity, linearity and sensi-ivity of the proposed biosensor appear to be enough for glucose

easurements in real samples analysis.

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cta 56 (2011) 1239–1245

4. Conclusions

We demonstrated the electrochemical and electrocatalyticbehaviors of a novel hybrid film modified electrode, which wassuccessfully prepared by electropolymerizing PB onto the GO modi-fied glassy carbon electrode. The GO/PB modified electrode showedhigher PB deposition, and larger peak current compared to the bareGC electrode. The GO/PB film modified electrode exhibited highelectrocatalytic activities toward the reduction of H2O2. Further-more, a glucose biosensor was successfully constructed based onthe GO/PB film modified electrode. The proposed biosensor exhib-ited good selectivity and could be effectively applied for glucosemeasurements in real samples. The enhanced electrochemical per-formances of GO/PB hybrids could be mostly attributed to theirunique 2D nanostructure, high specific surface area of the GOnanosheets as well as unique features of the PB film. This studyhas not only established a general route for fabricating grapheneoxide-based hybrid via electropolymerizing Prussian blue on ontothe GO modified electrode but also expanded the scope of grapheneoxide applications to the field of bioelectroanalytical chemistry,which may open up a new challenge and approach to explore theelectrochemical features of graphene or its hybrid materials for thepotential utilizations.

Acknowledgements

This work was supported by Program for New Century Excel-lent Talents in University (NCET-08-0897), NSFC (No. 20773088),National 973 Project (No. 2010CB933901), Shanghai Sci. & Tech.and Education Committee (08QH14020, 09SG43, 09zz137, S30406),LADP-SHNU (DZL806).

References

[1] A.K. Geim, K.S. Novoselov, Nat. Mater. 6 (2007) 183.[2] X.L. Li, X.R. Wang, L. Zhang, S.W. Lee, H.J. Dai, Science 319 (2008) 1229.[3] J.S. Bunch, A.M. van der Zande, S.S. Verbridge, I.W. Frank, D.M. Tanenbaum, J.M.

Parpia, H.G. Craighead, P.L. McEuen, Science 315 (2007) 490.[4] S. Gilje, S. Han, M. Wang, K.L. Wang, R.B. Kaner, Nano Lett. 7 (2007) 3394.[5] D. Li, R.B. Kaner, Science 320 (2008) 1170.[6] F. Schedin, A.K. Geim, S.V. Morozov, E.W. Hill, P. Blake, M.I. Katsnelson, K.S.

Novoselov, Nat. Mater. 6 (2007) 652.[7] N.Q. Jia, Z.Y. Wang, G.F. Yang, H.B. Shen, L.Z. Zhu, Electrochem. Commun. 9

(2007) 233.[8] M. Zhou, J. Ding, L.P. Guo, Q.K. Shang, Anal. Chem. 79 (2007) 5328.[9] L.N. Wu, X.J. Zhang, H.X. Ju, Biosens. Bioelectron. 23 (2007) 479.10] C.X. Cai, J. Chen, Anal. Biochem. 323 (2004) 75.11] C.E. Banks, T.J. Davies, G.G. Wildgoose, R.G. Compton, Chem. Commun. (2005)

829.12] W. Yang, K.R. Ratinac, S.P. Ringer, P. Thordarson, J.J. Gooding, F. Braet, Angew.

Chem., Int. Ed. Engl. 49 (2010) 2114.13] F.H. Li, J.X. Song, F. Li, X.D. Wang, Q.X. Zhang, D.X. Han, A. Ivaska, L. Niu, Biosens.

Bioelectron. 25 (2009) 883.14] Y. Wang, Y.M. Li, L.H. Tang, J. Lu, J.H. Li, Electrochem. Commun. 11 (2009) 889.15] Y. Wang, Y. Wan, D. Zhang, Electrochem. Commun. 12 (2010) 187.16] X.M. Wu, Y.J. Hu, J. Jin, N.L. Zhou, P. Wu, H. Zhang, C.X. Cai, Anal. Chem. 82 (2010)

3588.17] C.S. Shan, H.F. Yang, J.F. Song, D.X. Han, A. Ivaska, L. Niu, Anal. Chem. 81 (2009)

2378.18] T.M. Schreier, J.J. Rach, G.E. Howe, Aquaculture 140 (1996) 323.19] A.A. Karyakin, E.E. Karyakina, L. Gorton, J. Electroanal. Chem. 456 (1998) 97.20] F. Ricci, G. Palleschi, Biosens. Bioelectron. 21 (2005) 389.21] A.A. Karyakin, E.A. Puganova, I.A. Budashov, I.N. Kurochkin, E.E. Karyakina, V.A.

Levchenko, V.N. Matveyenko, S.D. Varfolomeyev, Anal. Chem. 76 (2004) 474.22] S. Wu, Y.Y. Liu, J. Wu, H.X. Ju, Electrochem. Commun. 10 (2008) 397.23] J.D. Qiu, M. Xiong, R.P. Liang, J. Zhang, X.H. Xia, J. Nanosci. Nanotechnol. 8 (2008)

4453.24] Y. Zou, L.X. Sun, F. Xu, Biosens. Bioelectron. 22 (2007) 2669.25] W.S. Hummers, R.E. Offeman, J. Am. Chem. Soc. 80 (1958) 1339.

26] X.M. Sun, Z. Liu, K. Welsher, J.T. Robinson, A. Goodwin, S. Zaric, H.J. Dai, Nano

Res. 1 (2008) 203.27] G. Wang, J. Yang, J. Park, X. Gou, B. Wang, H. Liu, J. Yao, J. Phys. Chem. C 112

(2008) 8192.28] L. Xia, R.L. McCreery, J. Electrochem. Soc. 146 (1999) 3696.29] J. Bai, B. Qi, C.N. Jean, L.P. Guo, Micropor. Mesopor. Mater. 119 (2009) 193.

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Y. Zhang et al. / Electrochi

30] J.X. Zeng, W.Z. Wei, X.Y. Liu, Y. Wang, G.M. Luo, Microchim. Acta 160 (2008)261.

31] K. Itaya, T. Ataka, S. Toshima, J. Am. Chem. Soc. 104 (1982) 4767.

32] E. Laviron, J. Electroanal. Chem. 101 (1979) 19.33] E. Laviron, L. Roullier, J. Electroanal. Chem. 443 (1998) 195.34] R. Garjonyte, A. Malinauskas, Sens. Actuator B 46 (1998) 236.35] J. Zhang, J. Li, F. Yang, B.L. Zhang, X.R. Yang, Electrochem. Commun. 638 (2010)

173.36] J.F. Zhai, Y.M. Zhai, D. Wen, S.J. Dong, Electroanalysis 21 (2009) 2207.

[[[[

[

cta 56 (2011) 1239–1245 1245

37] H. Behzad, H. Hassan, G. Lo, Sensor. Actuator B 147 (2010) 270.38] X.Y. Wang, H.F. Gu, F. Yin, Y.F. Tu, Biosens. Bioelectron. 24 (2009) 1527.39] J.Y. Chiu, C.M. Yu, M.J. Yen, L.C. Chen, Biosens. Bioelectron. 24 (2009) 2015.

40] M.P. O’Halloran, M. Pravda, G.G. Guilbault, Talanta 55 (2001) 605.41] Z. Wang, S.N. Liu, P. Wu, C.X. Cai, Anal. Chem. 81 (2009) 1638.42] M.H. Xue, Q. Xu, M. Zhou, J.J. Zhu, Electrochem. Commun. 8 (2006) 1468.43] Y.Z. Xian, Y. Hu, F. Liu, Y. Xian, L.J. Feng, L.T. Jin, Biosens. Bioelectron. 22 (2007)

2827.44] Z.H. Dai, J. Ni, X.H. Huang, G.F. Lu, J.C. Bao, Bioelectrochemistry 70 (2007) 250.