纳米颗粒模拟酶及应用(4)

研究了纳米颗粒的多酶活性,包括过氧化物酶和过氧化氢酶,以及在葡萄糖高灵敏检测中的应用.

E

LCITRAHCRAESERPrussianBlueModi edFerritinasPeroxidaseMimeticsandItsApplicationsinBiologicalDetectionZhangetal.

Fig.2.CharacterizationofPB-FtNPsandpureferritin.(a)TEMphotographofunstainedferritin(inset:HRTEMimageofferritin).(b)Negatively-stainedTEMphotographofferritin.(c)TEMphotographofunstainedPB-FtNPs(inset:HRTEMimageofPB-FtNPs).(d)Negatively-stainedTEMphotographofPB-FtNPs.(e)Hydrodynamicsizedistributionofferritin(averagediameteris10.9nm).(f)HydrodynamicsizedistributionofPB-FtNPs(averagediameteris22.8nm).

electrostaticadsorptionbetweenferritinandABTSandthatPB-FtNPshaveahigheraf nitytothesubstratethustheenhancedcatalyticoxidationofABTS,wheretheABTSthanTMBduelikelytotheexistenceofastrongironoxidecoreofferritinplayslikelyaweakcatalyticelectrostaticinteractionbetweenABTSandPB-FtNPs,role.Forcomparison,theintensiveabsorbancevariationasindicatedabove.TableIgivestheobtainedapparentwasobservedwhenusingPB-FtNPsascatalyst,indicat-steady-statekineticparameters.Thepreviouslyreportedingthehighperoxidase-likeactivityiscontributedbythePBMNPs(～10nm)arealsolistedforcomparison.Themodi cationofPB.

Theperoxidase-likeactivityofPB-FtNPswasalsoKmvalueofPB-FtNPsusingTMBassubstrateishigherinvestigatedbydeterminingtheapparentsteady-statethanthatforPBMNPs,suggestingthatthePB-FtNPshavekineticparametersofthecatalyticreaction.Withasuit-loweraf nityforTMBthanPBMNPs;theKablerangeofHwithHmvalueofPB-FtNPs2O2assubstrateismuchlowerthanMentencurveswere2O2concentrations,typicalMichaelis–observedforTMB(Fig.5(a))andPBMNPs,indicatingPB-FtNPsaremuchmoreaf nitytoABTS(Fig.5(b)).WithacertainrangeofTMBandH2O2thanPBMNPs,whichmakesitagoodreagentinABTSconcentrations,theMichaelis–MentencurveswereH2O2detection.ThekcatvalueofthePB-FtNPswithTMBobservedforHandH2O2arebothsmallerthanthatforPBMNPs,originat-2O2(Fig.5(c),(d)) Thedatawere ttedtotheMichaelis–Mentenmodeltoobtaintheparametersingfromthatferritinshellleadstothelowerexposureof(TableI).TheapparentKPBactivesurfacecomparedwithPBMNPs.However,theABTSassubstrateismuchmvaluesofPB-FtNPswithsmallerthanTMB,suggesting

kcatvalueofPB-FtNPsistwoordersofmagnitudeshigherthanFe3O4NPs(～10nm)reportedbyYang’sgroup.9 38

Theperoxidase-likeactivityofPB-FtNPswerealso0.90measuredatdifferentconditionsusingpHfrom2to12,pure ferritinthetemperaturefrom10 Cto75 Candthenanoparti-0.75

PB-Ft NPs

cleconcentrationfrom1 g/mLto7 g/mL.Theresultse

cn0.60showthecatalyticactivityofPB-FtNPsisdependentonabr0.45pH,temperatureandcatalystconcentration(Fig.6).TheosboptimalpHwasapproximately3.0whenthesubstrateisA0.30TMB,andtheactivitydecreasedwiththeincreasingpHfor0.15ABTS(Figs.6(a),(b)).Theoptimaltemperaturewas65 C(Fig.6(c)),implyingabroaderactivetemperaturerange0.00

200

300400500600700800

thannativeenzyme.Figure6(d)showsalinearabsorbanceWavelength (nm)

increasewithacorrelationcoef cientof0.99asafunctionofPB-FtNPsconcentration,indicatingthatPB-FtNPsweFig.3.

UV-visabsorptionspectraofferritinandPB-FtNPs.

preparedcanbeusedasaperoxidase-likemimetics.

4

J.Nanosci.Nanotechnol.12,1–8,2012

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