An acetylcholinesterase biosensor ionic liquid functionalizedgraphene–gelatin-modified electrode - 图文

Y.Zhengetal./SensorsandActuatorsB210(2015)389–397

393

C

B

Fig.5.EffectofpH(A),theconcentrationofIL-GRnanocomposite(B),AChEloading(C),thecross-linkingtimeofGA(E)andinhibitiontime(F)ontheresponseofthebiosensor.

3.2.ElectrochemicalbehavioroftheGA/AChE–IL-GR–Gel/GCEbiosensor

ItisalreadyknownthatIL-GRhavebeenusuallyutilizedtomodifytheelectrodestoenhancetherelevantdetection

sensitivity.Basedontheseconsiderations,electrochemicalstud-ies,suchaselectrochemicalimpedancespectroscopy(EIS)wasusedtocharacterizethepreparationprocessofGA/AChE–IL-GR–Gel/GCEbiosensor.InatypicalNyquistplot,thesemicircleportioncorrespondedtotheelectron-transferresistance(Ret)at

394

Y.Zhengetal./SensorsandActuatorsB210(2015)389–397

higherfrequencyrange.AsshowninFig.3,analmoststraightlineonbareGCE(curvea)wasexhibited,demonstratingachar-acteristicofadiffusion-controlledelectrochemicalprocess.Aftermodi?cationwithGel(Gel/GCE),theEISoftheresultinglayershowedsemicircledomainwithRet～4900??(curvec),suggestingthatGellayerblockedtheredoxprobetodiffusetowardtheelec-trodesurfaceduetotheinherentnon-conductivityofGel.ItcanbeseenthattheRetvalueoftheIL-GR–Gel/GCEelectrode(～3000??,curveb)wassmallerthanthatoftheGel/GCEelectrode,whichindicatedthatthepresenceofIL-GRcompositeontheelectrodesurfaceimprovedthereactivesite,reducedtheinterfacialresis-tance,andmadetheelectrontransfereasier,whichcanbeascribedtotheirhighaccessiblesurfaceandexcellentconductiveproperty.TheremarkableincreaseofRetontheGA/AChE–IL-GR–Gel/GCEelectrode(～12,000??,curved)con?rmedthesuccessfulimmobi-lizationofAChE.

CVresponseondifferentelectrodeswasstudiedinPBS(pH7.0)containing1.5mMATCl,andtheresultsareshowninFig.4.NodetectableresponsecouldbeobservedatIL-GR–Gel/GCE(curvea),Gel/GCE(curveb)andGA/AChE–IL-GR–Gel/GCE(curvec)inPBS.However,when1.5mMATClwasaddedintothePBS,obviousoxi-dationpeakswereobservedatGA/AChE–Gel/GCE(curved)andGA/AChE–IL-GR–Gel/GCE(curvee).Obviously,thesepeakscamefromtheoxidationofthiocholine,hydrolysisproductofATCl,cat-alyzedbytheimmobilizedAChE.Theoxidationpeakcurrentofthiocholinewas1.358?Aat～0.698VontheGA/AChE–Gel/GCEelectrode,andgotto3.234?Aat～0.673VontheGA/AChE–IL-GR–Gel/GCEelectrode.Thepeakpotentialwasnegativelyshiftedby0.025V,andthepeakcurrentwasincreasedby138.14%.ThiswasbecauseofthepresenceofIL-GRwiththeirinherentconduc-tivepropertiesinthecomposite.IL-GRthusprovidedaconductivepathwayforelectrontransferandpromotedelectron-transferreac-tionswhichincreasedpeakcurrentandsensitivityofthebiosensoratalowerpotential.UsingGelimmobilizationAChEonthesur-faceofAChE–IL-GR–Gel/GCEcouldmaintainhighenzymeactivityandimproveelectrontransmissionbetweentheenzymeandthemodi?edelectrode.

3.3.Optimizationparametersofthebiosensorperformance

ThebioactivityoftheimmobilizedAChEdependsonthepHofthePBS.TheeffectofsolutionpHonthepeakcurrentresponsewasstudiedinseriesofPBScontaining1.5mMATClbyDPV.AsshownFig.5A,thecurrentresponseincreasedwiththeincreaseofpHandreachedamaximumat7.0.Therefore,pH7.0wasselectedinthesubsequentexperiments.

Therelationshipbetweenthebiosensorresponseandthecon-centrationofIL-GRnanocompositeontheGelsolutionfrom0.25mgml?1to5.0mgml?1(m/V)wasalsoinvestigated(Fig.5B).Resultsshowedthatthepeakcurrentofmodi?edelectrodeincreasedwithincreasingtheconcentrationofIL-GRnanocompos-iteupto4mgml?1,afterthat,itdecreasedslowly.Thisisrelatedtothechangeofelectrodesurfaceareaandelectrontransferresis-tance.WhentheIL-GRamountwastoomuch,theelectrodesurfaceareakeptalmostunchanged,buttheresistanceincreased.There-fore,4mgml?1ofIL-GRsuspensionwasadoptedforfurtherstudy.Fig.5CdisplaystheeffectofAChEloadingonthebiosensorresponse.ItwasnoticedthattheDPVpeakcurrentincreasedwithincreasingtheamountofAChEandreachedthemaximumat0.25U.FurtherincreaseofAChEledtoanobviousdecreaseofthecur-rentresponse.Therefore,superabundantAChEpossiblyincreasedresistanceofthemodi?edelectrodeandwasunstable.ThismaybeduetothatthesuperabundantAChEpossiblyincreasedelectroderesistanceofthemodi?edelectrodeandwasunstable.Thus,0.25UofAChEwaschosenasanoptimalenzymeconcentrationforthefabricatedbiosensor.

Fig.6.Typicalcurrent–timeplotforthebiosensoronsuccessiveadditionsofATCltopH7.0PBSunderstirringatanappliedpotentialof0.70V.InsetshowsthecalibrationplotfortheATClsensor(upperright)andthereciprocalrelationshipbetweenATClconcentrationandthecurrentresponse(bottomleft).

Inordertoenhancethestabilityofthebiosensor,GelwasusedtoentraptheAChEonIL-GRandtoimproveelectronictransmissionbetweenAChEandIL-GR.GAwasusedasthecross-linkingagentfortheAChEbiosensor.TheAChE–IL-GR–Gel/GCEandGA/AChE–IL-GR–Gel/GCEbiosensorswerecontinuouslytestedsixtimesinPBS(pH7.0)containing1.5mMATCl.TheRSDoftheDPVcurrentresponsewas7.76%and4.58%,respectively.TheresultsshowedthattheGelentrappedAChEandGAcross-linkingeffectivelyimprovedstabilityoftheAChEbiosensor.Thecross-linkingtimeofGAplayedanimportantroleinthe?lm-formingofbiosensor.AscanbeseenfromFig.5D,Thehighestcurrentresponsewasobtainedatthetimeof20min.ShortertimemightcausetheleakageofAChEfromtheelectrode,whilelongertimecouldresultinthehinderedeffectonAChE.Asaresult,20mincross-linkingtimewaschosenfortheimmobilizationofAChE.

Theeffectofinhibitiontimeonbiosensorresponsewasalsoinvestigated.TheGA/AChE–IL-GR–Gel/GCEbiosensorwasincu-batedin1.0×10?9Mcarbarylstandardsolutionfordifferentperiodoftime.AsshowninFig.5E,theinhibitionrateshowedobviousincreasewiththeincreaseofinhibitiontimewithin5min,how-ever,whentheinhibitiontimewaslongerthan5min,therewasnoobviousincrease,indicatinganequilibrationstate.Thus,theopti-muminhibitiontimeof5minwasusedfortheincubationstepsinthisstudy.

3.4.DetectionofATClatGA/AChE–IL-GR–Gel/GCEbiosensor

AmperometrywasappliedtothedeterminationofATCl.Fig.6showsatypicalamperometriccurrent–timeresponseofthebiosen-soraftersuccessiveadditionofATCltopH7.0PBS.AstheinsetofFig.6shows,thecurrentlinearlyincreasedwiththeincreaseofATClconcentrationovertherangefrom0.1to1.4mM,andgotaplateauat1.5mM,indicatingatypicalMichealis–Menten

process.TheMichaelis–Mentenconstant(Kbe0.74mMaccordingtoLineweaver–Burkmapp

)wascalculatedtoequation,Thevaluewasmuchlowerthanthoseof1.75mMobtainedfromthecar-bonnanotubesmodi?edelectrode[28]and1.5mMobtainedfromthepolyethyleneiminemodi?edelectrode[29],indicatingthegoodaf?nityofAChEtothesubstrate.

Y.Zhengetal./SensorsandActuatorsB210(2015)389–397

395

Table1

Comparisonwithotherreportedbiosensorsforcarbarylandmonocrotophosdetection.

Electrodematerial

Linearrange(M)

Detectionlimit(M)

Analyte

Ref.

Au-MPAa-AChE/ChOb

AChE–CdS–Gc–CHITd/GCEAChE–TiO2-G/GCE

AChE–MWCNTs/AuNPs-CHIT/GCENFe/AChE–CSf/AgNPs–CGRg–NF/GCEAChE/Pt-CAsh/BDDi

AChE–Fe3O4NPs/c-MWCNTsj/ITOkAChE–MSFl–PVAm/GCEGA/AChE–IL-GR–Gel/GCEGA/AChE–IL-GR–Gel/GCE

1.0×10?8–1.0×10?61.0×10?8–1.0×10?55.0×10?9–7.5×10?87.5×10?8–1.0×10?51.0×10?7–1.0×10?51.0×10?12–1.0×10?81.0×10?11–1.0×10?61.0×10?10–7.0×10?82.2×10?10–4.5×10?81.0×10?14–1.0×10?81.0×10?13–5.0×10?8

6.0×10?93.5×10?91.5×10?9

CarbarylCarbarylCarbaryl

[30][31][32]

1.0×10?85.4×10?132.7×10?121.0×10?102.2×10?105.3×10?154.6×10?14

MonocrotophosCarbaryl

MonocrotophosMonocrotophosMonocrotophosCarbaryl

Monocrotophos

[33][34][35][36][37]

ThisworkThiswork

abcdefghijklm

Mercaptopropionicacid.Cholineoxidase.Graphene.Chitosan.Na?on.Chitosan.

Carboxylicgraphene.Carbonaerogels.

Boron-dopeddiamond.

Carboxylatedmultiwalledcarbonnanotubes.Indiumtinoxide.

Mesocellularsilicafoam.Poly(vinylalcohol).

3.5.Detectionofthepesticides

Afterincubationofthebiosensorwithdifferentconcentrationsofcarbaryl,amperometricresponsesofthebiosensorwereinves-tigated,asshowninFig.7A.ItshowedthatcarbarylreducedtheactivityoftheimmobilizedAChE,andrelativeinhibitionincreasedwhencarbarylconcentrationsincreased.Fig.7Bshowsthecali-brationplotsofcarbarylandmonocrotophos.LinearequationofcarbarylwasI(%)=8.05lgc+121.42(R=0.995)from1.0×10?14to1.0×10?8M.LinearequationofmonocrotophoswasI(%)=10.40lgc+149.87(R=0.997)from1.0×10?13to5.0×10?8M.Thedetec-tionlimitsofcarbarylandmonocrotophoswere5.3×10?15Mand4.6×10?14M,respectively.ThecomparisonbetweentheperformanceofthebiosensorandotherreportedAChEbiosensorsintheliteraturewassummarizedinTable1.ComparedwithAu-MPA-AChE/ChO(linearrange:1.0×10?8–1.0×10?6M)[30],AChE–CdS–G–CHIT/GCE(linearrange:1.0×10?8–1.0×10?5M)[31],AChE–TiO2–G/GCE(linearrange:5.0×10?9–7.5×10?8M;7.5×10?8–1.0×10?5M)[32]andAChE–MWCNTs/AuNPs-CHIT/GCE(linearrange:1.0×10?7–1.0×10?5M)[33]biosensors,theproposedbiosensorwasmoresensitivefordetectinglowconcentrationsofpesticidesthanhighconcentrationsofpes-ticides.Moreover,itcanbeseenthatthepresentbiosensorexhibitedwiderlinearrangeandlowerdetectionlimitthanNF/AChE–CS/AgNPs–CGR–NF/GCE[34],AChE/Pt-CAs/BDD[35],AChE–Fe3O4NPs/c-MWCNTs/ITO[36]andAChE–MSF–PVA/GCE[37]biosensorsindetectinglowconcentrationsofpesticides.ThehighersensitivitymaybeduetothefactthatIL-GRcompositecouldincreasethesurfacearea,thusraisedAChEadsorption.On

theotherhand,theformationofcrosslinkednetworkinvolvingGA,IL-GR,GelandtheenzymepreventedtheAChEfromleakingef?ciently.Here,GelservedtheduelfunctionsofcrosslinkingwithGAandprovidingofabiocompatiblemicroenvironmenttoAChEinsidetheIL-GRmatrix.Therefore,thebiosensorexhibitedenhancedsignaloutputwhichwasnotseenearlierwithanyotherAChEbasedbiosensors.

3.6.Analysisofcarbarylandmonocrotophosinspikedtomatojuicesamples

Tomatojuiceswerespikedwithvaryingconcentrationofcar-barylandmonocrotophosasdescribedinSection2.6andweremeasuredtoevaluatethereliabilityoftheproposedGA/AChE–IL-GR–Gel/GCEbiosensor.AsshowninTable2,forcarbaryldetection,therecoverieswerefoundtobebetween92.5%and105.0%.Formonocrotophosdetection,therecoverieswerefoundtobebetween91.2%and110.0%.Theresultsindicatedthattheproposedbiosensorisacceptablyaccurateandprecise,andcanbeusedfortheanalysisofsamplesfromarealenvironment.

3.7.Reproducibility,stabilityoftheGA/AChE–IL-GR–Gel/GCEbiosensor

ThereproducibilityoftheGA/AChE–IL-GR–Gel/GCEbiosensorwasevaluatedbyanalyzingcarbarylforeightreplicatemea-surementsin1.5mMATClafterbeingtreatedwith20×10?10Mcarbarylfor5min.Similarly,theinter-assayprecisionwasesti-matedat?vedifferentelectrodesforthedeterminations.The

Table2

Determinationofcarbarylandmonocrotophosinthesample.

Sample

Added(M)

Carbaryl

Monocrotophos

Found(M)

Meanrecovery(%)±S.D.(n=4)

Found(M)

Meanrecovery(%)±S.D.(n=4)

12345

2.0×10?118.0×10?112.0×10?108.0×10?108.0×10?9

2.1×10?117.5×10?111.9×10?107.4×10?108.3×10?9

105.093.895.092.5103.8

±±±±±

4.43.24.74.53.8

1.9×10?118.5×10?112.2×10?107.7×10?107.3×10?9

95.0106.2110.096.391.2

±±±±±

3.54.63.94.83.3

ˉ±Mean±S.D.=x

ts√.n396

Y.Zhengetal./SensorsandActuatorsB210(2015)389–397

Fig.7.(A)DPVoftheGA/AChE–IL-GR–Gel/GCEbiosensorin0.1MPBS(pH7.0)containing1.5mMATClafterincubationwith0(a),1.0×10?14(b),5.0×10?14(c),1.0×10?13(d),5.0×10?13(e),1.0×10?12(f),5.0×10?12(g),1.0×10?11(h),5.0×10?11(i),1.0×10?10(j),5.0×10?10(k),1.0×10?9(l),5.0×10?9(m)and1.0×10?8M(n)carbarylfor5min.(B)TheinhibitionrateoftheGA/AChE–IL-GR–Gel/GCEbiosensorversusthelogarithmofcarbarylconcentration(a)andmonocrotophosconcentration(b).

coef?cientofvariationofintra-assayandinter-assaywas4.14%and5.59%,respectively,whichindicatedthattheGA/AChE–IL-GR–Gel/GCEbiosensorwasreproducibleandprecise.ThepreparedGA/AChE–IL-GR–Gel/GCEbiosensorwasstoredat4?Cwhennotinuse.Aftera15daystorageperiod,thebiosensorretained95.2%ofitsinitialcurrentresponse,provingtheacceptablestability.

4.Conclusion

AnAChEbiosensorbasedonIL-GR–Gelhasbeendeveloped.ThestabilityoftheAChEbiosensorwasimprovedbyusingGAascross-linkertoimmobilizetheAChEontheIL-GR–Gel/GCE.OwingtotheexcellentpropertyofIL-GR–Gelcompositesuchasexcellentelectricalconductivity,highaccessiblesurfaceareaandgoodbiocompatibility,thepreparedGA/IL-GR–Gel/GCEbiosensorshowedhighersensitivity,lowerdetectionlimit,goodfabricationreproducibilityandacceptablestabilitytowardOPsdetection.Themethodnotonlycanbeusedtoimmobilizeenzymestoconstructarangeofbiosensorsbutalsomaybeextendedtoassembleotherbiologicalmolecules,suchasantibodyandDNAforbioassay.

Acknowledgment

ThisresearchwassupportedbyNationalNaturalScienceFoun-dationofChina(No.21275039).

References

[1]C.Chen,Y.Z.Qian,Q.O.Chen,C.J.Tao,C.Y.Li,Y.Li,Evaluationofpesticide

residuesinfruitsandvegetablesfromXiamen,China,FoodControl22(2011)1114–1120.

[2]H.Berrada,M.Fernández,M.J.Ruiz,J.C.Moltó,J.Ma?nes,G.Font,Surveillance

ofpesticideresiduesinfruitsfromValenciaduringtwentymonths(2004/05),FoodControl21(2010)36–44.

[3]F.P.Carvalho,Agriculture,pesticides,foodsecurityandfoodsafety,Environ.

Sci.Policy9(2006)685–692.

[4]D.Du,M.Wang,J.Cai,A.Zhang,Sensitiveacetylcholinesterasebiosensorbased

onassemblyof?-cyclodextrinsontomultiwallcarbonnanotubesfordetectionoforganophosphatespesticide,Sens.ActuatorsB146(2010)337–341.

[5]R.Rawal,S.Chawla,T.Dahiya,C.S.Pundir,Developmentofanamperometric

sul?tebiosensorbasedonagoldnanoparticles/chitosan/multiwalledcar-bonnanotubes/polyaniline-modi?edgoldelectrode,Anal.Bioanal.Chem.401(2011)2599–2608.

[6]P.Raghu,T.MadhusudanaReddy,B.KumaraSwamy,B.Chandrashekar,K.

Reddaiah,M.Sreedhar,DevelopmentofAChEbiosensorforthedeterminationofmethylparathionandmonocrotophosinwaterandfruitsamples:acyclicvoltammetricstudy,J.Electroanal.Chem.665(2012)76–82.

[7]A.K.Geim,K.S.Novoselov,Theriseofgraphene,Nat.Mater.6(2007)183–191.[8]J.Xiao,D.Mei,X.Li,W.Xu,D.Wang,G.L.Graff,W.D.Bennett,Z.Nie,L.V.Saraf,

I.A.Aksay,Hierarchicallyporousgrapheneasalithium–airbatteryelectrode,NanoLett.11(2011)5071–5078.

[9]M.D.Stoller,S.Park,Y.Zhu,J.An,R.S.Ruoff,Graphene-basedultracapacitors,

NanoLett.8(2008)3498–3502.

[10]J.D.Qiu,J.Huang,R.P.Liang,Nanocomposite?lmbasedongrapheneoxide

forhighperformance?exibleglucosebiosensor,Sens.ActuatorsB160(2011)287–294.

[11]J.F.Wu,M.Q.Xu,G.C.Zhao,Graphene-basedmodi?edelectrodeforthedirect

electrontransferofcytochromecandbiosensing,Electrochem.Commun.12(2010)175–177.

[12]P.Wu,Q.Shao,Y.Hu,J.Jin,Y.Yin,H.Zhang,C.Cai,Directelectrochemistryof

glucoseoxidaseassembledongrapheneandapplicationtoglucosedetection,Electrochim.Acta55(2010)8606–8614.

[13]B.Yu,D.Kuang,S.Liu,C.Liu,T.Zhang,Template-assistedself-assemblymethod

topreparethree-dimensionalreducedgrapheneoxidefordopaminesensing,Sens.ActuatorsB205(2014)120–126.

[14]S.Liu,J.Q.Tian,L.Wang,H.L.Li,Y.W.Zhang,X.P.Sun,Stableaqueous

dispersionofgraphenenanosheets:noncovalentfunctionalizationbyapoly-mericreducingagentandtheirsubsequentdecorationwithAgnanoparticlesforenzymelesshydrogenperoxidedetection,Macromolecules43(2010)10078–10083.

[15]S.Stankovich,D.A.Dikin,G.H.Dommett,K.M.Kohlhaas,E.J.Zimney,E.A.Stach,

R.D.Piner,S.T.Nguyen,R.S.Ruoff,Graphene-basedcompositematerials,Nature442(2006)282–286.

[16]D.Li,R.B.Kaner,Graphene-basedmaterials,Nat.Nanotechnol.3(2008)

101–105.

[17]D.Wei,A.Ivaska,Applicationsofionicliquidsinelectrochemicalsensors,Anal.

Chim.Acta607(2008)126–135.

[18]B.G.Choi,H.Park,T.J.Park,D.H.Kim,S.Y.Lee,W.H.Hong,Developmentof

theelectrochemicalbiosensorfororganophosphatechemicalsusingCNT/ionicliquidbuckygelelectrode,Electrochem.Commun.11(2009)672–675.

[19]H.Yang,C.Shan,F.Li,D.Han,Q.Zhang,L.Niu,Covalentfunctionalizationof

polydispersechemically-convertedgraphenesheetswithamine-terminatedionicliquid,Chem.Commun.26(2009)3880–3882.

[20]M.Du,T.Yang,S.Ma,C.Zhao,K.Jiao,Ionicliquid-functionalizedgrapheneas

modi?erforelectrochemicalandelectrocatalyticimprovement:comparisonofdifferentcarbonelectrodes,Anal.Chim.Acta690(2011)169–174.

[21]C.Shan,H.Yang,D.Han,Q.Zhang,A.Ivaska,L.Niu,Electrochemicaldetermi-nationofNADHandethanolbasedonionicliquid-functionalizedgraphene,Biosens.Bioelectron.25(2010)1504–1508.

[22]H.Yao,N.Li,J.Z.Xu,J.J.Zhu,Directelectrochemistryandelectrocatalysisof

hemoglobiningelatine?lmmodi?edglassycarbonelectrode,Talanta71(2007)550–554.

[23]A.P.Periasamy,Y.J.Chang,S.M.Chen,Amperometricglucosesensorbasedon

glucoseoxidaseimmobilizedongelatin-multiwalledcarbonnanotubemodi-?edglassycarbonelectrode,Bioelectrochemistry80(2011)114–120.

[24]J.Liu,H.Liu,L.Wang,Explorationofamino-functionalizedionicliquidsasligand

andbaseforHeckreaction,Appl.Organomet.Chem.24(2010)386–391.

[25]W.S.Hummers,R.E.Offeman,Preparationofgraphiticoxide,J.Am.Chem.Soc.

80(1958)1339.

[26]X.S.Guo,X.Y.Zhang,Q.Cai,T.Shen,S.M.Zhu,Developinganovelsensitivevisual

screeningcardforrapiddetectionofpesticideresiduesinfood,FoodControl30(2013)15–23.

[27]S.J.Guo,D.Wen,Y.M.Zhai,S.J.Dong,E.K.Wang,Ionicliquid–graphenehybrid

nanosheetsasanenhancedmaterialforelectrochemicaldeterminationoftrini-trotoluene,Biosens.Bioelectron.26(2011)3475–3481.

Y.Zhengetal./SensorsandActuatorsB210(2015)389–397

397

[28]G.Liu,Y.Lin,Biosensorbasedonself-assemblingacetylcholinesteraseoncar-bonnanotubesfor?owinjection/amperometricdetectionoforganophosphatepesticidesandnerveagents,Anal.Chem.78(2006)835–843.

[29]D.Du,X.Ye,J.Cai,J.Liu,A.Zhang,Acetylcholinesterasebiosensordesignbased

oncarbonnanotube-encapsulatedpolypyrroleandpolyanilinecopolymerforamperometricdetectionoforganophosphates,Biosens.Bioelectron.25(2010)2503–2508.

[30]A.Hate?-Mehrjardi,Bienzymeself-assembledmonolayerongoldelectrode:

anamperometricbiosensorforcarbaryldetermination,Electrochim.Acta114(2013)394–402.

[31]K.Wang,Q.Liu,L.Dai,J.Yan,C.Ju,B.Qiu,X.Wu,Ahighlysensitiveandrapid

organophosphatebiosensorbasedonenhancementofCdS-decoratedgraphenenanocomposite,Anal.Chim.Acta695(2011)84–88.

[32]K.Wang,H.N.Li,J.Wu,C.Ju,J.J.Yan,Q.Liu,B.Qiu,TiO2-decoratedgraphene

nanohybridsforfabricatinganamperometricacetylcholinesterasebiosensor,Analyst136(2011)3349–3354.

[33]P.Norouzi,M.Pirali-Hamedani,M.Ganjali,F.Faridbod,Anovelacetyl-cholinesterasebiosensorbasedonchitosan–goldnanoparticles?lmfordeterminationofmonocrotophosusingFFTcontinuouscyclicvoltammetry,Int.J.Electrochem.Sci.5(2010)1434–1446.

[34]Y.Liu,G.Wang,C.Li,Q.Zhou,M.Wang,L.Yang,Anovelacetylcholinesterase

biosensorbasedoncarboxylicgraphenecoatedwithsilvernanoparticlesforpesticidedetection,Mater.Sci.Eng.C35(2014)253–258.

[35]Y.Liu,M.Wei,Developmentofacetylcholinesterasebiosensorbasedon

platinum–carbonaerogelscompositefordeterminationoforganophosphoruspesticides,FoodControl36(2014)49–54.

[36]N.Chauhan,C.S.Pundir,Anamperometricacetylcholinesterasesensorbasedon

Fe3O4nanoparticle/multi-walledcarbonnanotube-modi?edITO-coatedglassplateforthedetectionofpesticides,Electrochim.Acta67(2012)79–86.

[37]S.Wu,L.Zhang,L.Qi,S.Tao,X.Lan,Z.Liu,C.Meng,Ultra-sensitivebiosensor

basedonmesocellularsilicafoamfororganophosphorouspesticidedetection,Biosens.Bioelectron.26(2011)2864–2869.

Biographies

YingyingZhengiscurrentlypursuingherMaster’sdegreeunderthesupervisionofZhiminLiuinHenanUniversityofTechnology.Herresearchinterestismainlyfocusedonelectrochemicalbiosensors.

ZhiminLiu,ProfessorofChemistry,CollegeofChemistryandChemicalEngineering,HenanUniversityofTechnology,China.ShereceivedherPh.D.degreeinAnalyti-calChemistryfromHunanUniversityin2005.Dr.Liu’sresearchinterestsinvolvechemicalsensors,biosensorsandelectroanalyticalchemistry.

YanfengJingiscurrentlyaM.S.candidateinHenanUniversityofTechnology.Herresearchactivityismainlyfocusedonelectrochemicalbiosensors.

JieLiiscurrentlyaM.S.candidateinHenanUniversityofTechnology.Hercurrentresearchworkisconcentratedonelectrochemicalbiosensors.

HaijunZhan,AssociateProfessorofChemistry,CollegeofChemistryandChemicalEngineering,HenanUniversityofTechnology,China.HereceivedhisPh.D.degreeinAnalyticalChemistryfromWuhanUniversityin2008.Hisresearchinterestismainlyfocusedonelectrochemicalbiosensors.