Electrical Sensing of Au Nanoparticles Manipulated by an Optical Vortex - Nakatsuka et al. - 2021 - Unknown

《Electrical Sensing of Au Nanoparticles Manipulated by an Optical Vortex - Nakatsuka et al. - 2021 - Unknown》由会员上传分享，免费在线阅读，更多相关内容在学术论文-天天文库。

pubs.acs.org/JPCCArticleElectricalSensingofAuNanoparticlesManipulatedbyanOpticalVortexRyojiNakatsuka,SyuheiYanai,KichitaroNakajima,KentaroDoi,andSatoyukiKawano*CiteThis:J.Phys.Chem.C2021,125,9507−9515ReadOnlineACCESSMetrics&MoreArticleRecommendations*sıSupportingInformationABSTRACT:Recently,electricalsensingtechniquesofsinglesmallobjects,suchasnanoparticles,viruses,andbiomolecules,haveattractedmuchattention.However,fine-tuningofasensingsectionisrequiredtoachievehighthroughputandhighprecision.Herein,weproposeanovelmethodtoimprovethemeasurementaccuracyofelectricalsignalsusingadouble-nanoslitstructureexposedtoanopticalvortex.AsmallAuparticlewithadiameterof200nmdispersedinaphosphate-bufferedsalinesolutionisopticallytrappedandmanipulatedinanorbitof2.3μmindiameteratthenanoslitstructure.ThisorbitalmotionenablesustorepetitivelysenseelectricalsignalsofasmallAuparticle.Asaresult,anelectricalresponseofafewhundredpicoampereswithinsometensofmillisecondsisfinelyshapedremovingnoise.Thisresultmayprovideapromisingtechniquefortheidentificationofsingletargetobjectsatthenanoscale.■INTRODUCTIONtrappedAuNPisperiodicallytransportedthroughthedoubleNanoporetechnologiesforsinglenanoparticledetectionhaveslitinanioniccurrentcondition.Asaresult,theioniccurrentbeendevelopedfordecades.1−10Especially,nanoporesensorsmeasurementimprovesthewaveformofelectricalsignals,areexpectedtoestablishapromisingmethodtoidentifysmallremovingnoisebysynchronouslyaveragingtheperiodicorbitalobjects,suchassinglebiomoleculesandviruses.3−5Onthemotions.AconventionalCoultercounterusuallysensesaotherhand,highthroughputseemstobeamajorproblemthatsinglepulseofaparticleusingacomparablesizepore,whichshouldbesolvedbecausethetransportoftargetobjectsisrequiresthehighresolutionofelectricalsignalsasparticles3,4,38,39stronglyfluctuatedandisdisturbedonthewaytoasensingbecomesmaller.Recently,severalnovelmethodsweresection.Inaddition,weakelectricalsignalsofsmallobjectsarealsoproposedtoimprovethesensingaccuracyofelectrical16,40,41oftenhiddenbehindnoise,whichcausestherequirementofmeasurementsofsmallparticles.ThepresentstudyDownloadedviaUNIVOFCONNECTICUTonMay16,2021at12:04:55(UTC).carefultreatmentsforelectricalmeasurements.Usingmicro-providesamethodtorecovertheweaknessofnanoparticleandnanofluidicchannelsthatguideelectricallychargedobjectselectricalmeasurementsusinganopticalvortex.Ithasalreadybytheelectrophoresisand/orelectroosmoticflows(EOFs),beenreportedthatfluidicchannelsandparticlesusuallyhaveSeehttps://pubs.acs.org/sharingguidelinesforoptionsonhowtolegitimatelysharepublishedarticles.thetransportefficiencymaybeimprovedwhenthedesignofsurfacecharges,whichformelectricdoublelayers(EDLs)thatthedevicesisoptimized.11−14Wealsopreviouslyproposed11becomethickerorthinnerdependingonsaltconcentrations.somemethodsforthemeasurementofresistivepulses,Whenaparticlepassesthroughananoporeornanochannel,(i)controllingthetransportoftargetparticlesusingopticaltheelectricresistanceincreasesduetotheexcludedvolume15,16manipulationtechniques.Suchopticaltechniqueshaveand(ii)thesaltconcentrationlocallyincreasesandthe17−19beenusedinvariousresearchfieldssincethepotentialofconductivityalsoincreasesduetocounterionsbroughtintobyopticaltweezerswasdemonstratedbyAshkinandhisco-theparticle,whichdeterminetheresultwhetherdecreasingor20−2324,25workers.Opticalmanipulationofbiologicalcells,increasingoftheioniccurrentiscausedbythesuperpositionof2627,28biomacromolecules,andsmallcolloidparticleswasusedthetwocomponentsmentionedabove.39,42−44Thephenom-toaccuratelydeterminethepositionsortoformordered29−33structures.Inthisstudy,wefurtherapplyanopticalvortexthatinducesanorbitalmotionofagoldnanoparticle(AuNP).Received:February28,2021Anopticalvortex,whichhasanorbitalangularmomentumRevised:April15,2021(topologicalcharge),drivesasmallobjectintoacircularorbitalPublished:April27,202129,34−37motionduetothegradientandscatteringforces.Herein,adouble-slitstructureisfabricatedinananochannelandthesizeisadjustedtotheorbitalradius.Anoptically©2021AmericanChemicalSocietyhttps://doi.org/10.1021/acs.jpcc.1c018049507J.Phys.Chem.C2021,125,9507−9515

1TheJournalofPhysicalChemistryCpubs.acs.org/JPCCArticleFigure1.(a)Schematicdiagramoftheopticalsetupandthedouble-slitstructureembeddedatthecenterofthenanochanneldevice.(b)Dark-fieldmicroscopyandscanningelectronmicroscopyimagesofthedoubleslitinthenanochanneldevice.AdispersionofAuNPsisinjectedfromtheinletsmadebyPDMSatbothendsofthedoubleslit.enon(i)iswellunderstoodbytheCoulterprincipleand(ii)injectedintothePDMSmicrochannelandintroducedtothe39hasnotyetbeensufficientlyreportedusingAuNPs.Itisdouble-slitstructure.Thedispersionispreparedusingsuspectedthatthesimultaneousoccurrenceofbothcurrentphosphate-bufferedsaline(PBS)(FUJIFILMWakoPureincreaseanddecreaseiscausedbybothreasons(i)and(ii)ChemicalCorp.,Osaka,Japan)with1wt%ofnonionicandthatthevolumeexclusioneffectisusuallymoredominantsurfactantofTritonX-100(MPBiomedicalsLCC,SantaAna,thantheexcesschargeinduction.ThisstudyaimstoCA,USA).AAuNPtrappedbyanopticalvortexthroughanexperimentallyelucidatetheeffectofAuNPtransportoninvertedmicroscope(IX-71,OlympusCorp.,Tokyo,Japan)istheioniccurrentusingadoublenanoslitandanopticalvortex.transportedaroundthecenterpostofthedouble-slitstructure,Thepresentmethodisexpectedtobeaveryimportantbeingpushedtothetopfaceofthechannel.Anopticalvortextechniquetoobtaindetailedinformationaboutthesmallinducesboththescatteringforce,whichpushesanobjectnumberofsinglemoleculesorvirusesthatareusuallyrareinforwardalongtheopticalaxis,andthegradientforce,whichsamples.attractsanobjecttothetorus-likepotentialwell.Asaresult,aAuNPisrestrictedtoaninplanecircularorbitalmotionina■nanochannel.Herein,thepowerofthelaserbeamistunedatEXPERIMENTALMETHODS87or110mWinfrontofanobjectivelens(N.A.=0.65,OpticalandElectricalMeasurements.TheopticalsetupLCPLN50×IR,OlympusCorp.Tokyo,Japan).AsshowninisshowninFigure1a.Anear-infraredlaserbeamwithaFigure1b,opticalobservationisfocusedatthedoubleslitinawavelengthof1064nm(LS0100FSCG,OXIDECorp.,nanochannel,asmagnifiedinthefigure.TrajectoriesoftheAuHokuto,Japan)ismodulatedtoaLagurreGaussian(LG)NParevisualizedusingadark-fieldcondenserandrecordedbybeambyusingaliquidcrystalonasiliconspatiallightascientificcomplementarymetal-oxidesemiconductormodulator(LCOS-SLM,X13138-03,HamamatsuPhotonics(sCMOS)high-speedcamera(Zyla4.2,AndorTechnologyK.K.,Hamamatsu,Japan).AgeneratedopticalvortexirradiatesLtd.,Belfast,NorthernIreland)withaframerateof1000fps.adouble-slitstructureembeddedinananofluidicchannel,Detailsoftheopticalsetuparealsopublishedelsewhere.33Anwhichisfabricatedonaquartzglasssubstrate170μmthick,electricvoltageisappliedacrossthedouble-slitstructureusingusingelectronbeamlithography(JSM-7200,JEOLLtd.,Ag/AgClwireelectrodesinsertedintotheinletandoutletTokyo,JapanandBeamDraw,TokyoTechnology,Corp.,holesthroughthePDMSsubstrate.TheotherendsoftheTokyo,Japan)andreactiveionetching(RIE-10NR,Samcoelectrodesareconnectedtoavoltagesource(PMX18-5A,Inc.,Kyoto,Japan).Apostof2.3μmindiameterisdesignedKikusuiElectronicsCorp.,Yokohama,Japan)orcurrentforanangularmomentumoftheopticalvortexandtwowallsamplifier(VersaSTAT4,AMETEKInc.,Berwyn,PA,USA).arelocatedneartheposttoformadouble-slitstructurewithaIoniccurrentinaPBSsolutionismeasuredatasamplinggapof300nm.Theheightoftheslitsisapproximately350nm,frequencyof2.0kHz,andtheelectricalsignalisprocessedbyawhichispreferableforatargetAuNPwithadiameterof200low-passfilterof10Hz.Thenanochanneldeviceisenclosedinnm(A11-200-CIT-DIH-1-25-CS,NanopartzInc.,Loveland,aFaradaycageduringexperiments.ThepresentelectricalCO,USA).Thetopfaceissealedwithapolydimethylsiloxanemeasurementsetupisconstructedbasedonourprevious(PDMS)substrate(Sylgard184SiliconeElastomerKit,Dow16study.Inc.,Midland,MI,USA)onwhichmicrochannelpatternsareSingleAuNPSensingBasedontheCoulterPrinciple.printedusinganegativephotoresistmold(SU-83050,ManyworksaboutelectricalsensingofsmallobjectsbasedonKAYAKUAdvancedMaterialsInc.,Westborough,MA,USA)theconventionalCoulterprinciplehavealreadybeenpublished3−5madebysoftlithographytechniques(PALET,NeoarkCorp.,andreviewed,whereresistivepulsescausedbythevolume1,8,10,16Tokyo,Japan).InletsandoutletsfortheAuNPdispersionareexclusionoftargetparticleswereoftenmeasured.43madeusingabiophyspunchof3.5mmindiameter.ThroughParticularly,Smeetsetal.experimentallyclarifiedthetheholes,adispersionofAuNPswithadiameterof200nmiscrossoverpointofelectrolyteconcentrationsbetweenresistive9508https://doi.org/10.1021/acs.jpcc.1c01804J.Phys.Chem.C2021,125,9507−9515

2TheJournalofPhysicalChemistryCpubs.acs.org/JPCCArticleandconductivepulsesoftargetparticlesusingnanopores.Itis■RESULTSANDDISCUSSIONsuspectedthatcounterionsattractedtoanegativelychargedAuOpticalandElectricalMeasurementsofaAuNPNParebroughtintothenanostructurethroughanelectrolyteDrivenbyanOpticalVortex.Figure3showsresultsfromsolution,asshowninFigure2a.Asusual,electrolyteionsthecurrentmeasurementofaAuNPof200nmindiameterperiodicallypassingthroughthedoubleslit,whichwasmanipulatedbyanopticalvortex.Here,wesucceededincontinuouslychangingthetopologicalchargemoftheopticalvortexduringtheelectricalmeasurement(SupportingInformationMovieS1).Thistechniqueisfoundtobeavailabletoclarifytheeffectofliquidflowsontheioniccurrentresponsesinducedbytheparticletransport.AsshowninFigure3a,b,synchronizingthecurrentmeasurementandopticalobservationofaAuNPthatwasmanipulatedbyanopticalvortexofm=3,ioniccurrentresponseswereobtainedasafunctionoftheparticlepositions.WhenaAuNPwasrevolvedthroughthenanoslitstructureina2×PBSsolutionthatincluded276mMNaCl,theioniccurrentresponseshowedbothconductiveandresistivepulses,asshowninFigure3b.Inaddition,itwasfoundthatthethroughputofconductivecurrentpulsesmadebythesingleAuNPwasabout10Hz.CorrespondingtothesnapshotsshowninFigure3a,sharppeaksarerecognizedwhenaAuNPisattheupperslit(slitA)andthelowerslit(slitB),whichareindicatedby(iii)att=10.405sand(i)att=10.278sinFigure3c,respectively.Itisinterestingthatbothconductiveandresistivepulsescanbeobtainedfromasingleparticle.Inthiskindofexperiment,Figure2.Conceptsofioniccurrentresponses.(a)AnegativelybasedontheCoulterprinciple,weusuallyrecognizeparticleschargedAuNP,whichattractscounterionstothesurface,usuallybyresistivepulsesduetothevolumeexclusioneffect.InpassesthroughananoslitdrivenbyelectrophoresisagainstEOF.Ions39,42,43previousstudies,conductivepulseswereexplainedbyexcludedbytheparticlecausethecurrenttodecreasealthoughthenegativechargeofAuNPandcounterionsalsocontributetothetheincreaseofionconcentrationsinnanostructures,whichwascurrent.(b)ThetransportofaAuNPcanbereversedandfollowbroughtbyatargetobjectindilutesolutions.Here,itisEOFusingopticalmanipulation.ThenegativechargeandcounterionssuspectedthatthetransportofaAuNPdirectedbyanopticalmayeffectivelycontributetoconductivecomponentsdominantinvortexfollowingoragainstaliquidflowisreflectedinthesufficientlysmallstructures.(c)Ioniccurrentresponseresultingfromcurrentpulses.Innanofluidicchannels,EOFsareusuallythesuperpositionofresistiveandconductivecomponents.inducedbycounterionsnearelectricallychargedchannelwalls.ThequartzglassandPDMSsubstratewereconfirmedtobeequivalenttotheparticlevolumeareexcludedfromthenegativelycharged16andtheycausedthenegativeζ-potentialnanostructureandcauseanioniccurrentdecreaseifthethatattractedcounterionsandinducedanEOF.InFigure3,anelectricalconductivityisconstant.Ontheotherhand,aselectricfieldisdirectedfromthelefttotheright.Thus,theshowninFigure2b,theioniccurrentispossiblyrecoveredparticleseemstobefollowinganEOFatslitAandagainstatwhentheelectricalconductivityismodulatedbycounterionsslitB.AscorrespondingcurrentpulsesshowninFigure3c,42,43highlyconcentratedneartheparticleorchannelsurfaces,conductiveandresistivepulsesweresensedatslitAandslitB,whichischaracterizedbytheDebyelength,forexample,respectively.Intheexperiment,theparticletransportwas2successivelychangedfromtheclockwisedirectiontotheassumingmonovalentions:λ=εεr0BkT/(2enb),whereεristherelativedielectricconstant,ε0isthedielectricconstantofcounterclockwisedirectionbychangingmfrom3to−3(seevacuum,kBistheBoltzmannconstant,TistheabsoluteMovieS1).Figure3dshowssnapshotsofacounterclockwisetemperature,eistheelementarycharge,andnbisthebulktranslocationandFigure3e,fshowscorrespondingcurrentnumberdensity.Inthisstudy,PBSsolutions,whichcontain69,pulses.Inthiscase,theioniccurrentresponsebecomes276,or552mMNaCl,wereused,andtheDebyelengthsconductiveandresistiveatslitBandslitA,respectively.Thiscorrespondingtotheseelectrolyteconcentrationsweretrendisreversedtotheformerclockwisecase.Theseresultsestimatedtobe1.3,0.58,and0.41nm,respectively.Forarevealthatthedifferencebetweentheconductiveandresistiveparticleradiusa,electrolyteionsareexcludedfromthenanoslitresponsesdependsontherelativityoftheparticletransporttobytheparticlevolume4πa3n/3andareprovidedbythetheelectricfieldandtheEOFfromthelefttotherightbcounterions4πa2λn′,wheren′istheeffectivenumberdensitydirectionatthenarrowslits.AAuNPtookadurationof0.075involvingtheEDL.Therefore,theirsuperposition,4πa2λn′−sfromalocationatt=10.360s[Figure3a(ii)]tothatatt=4πa3n/3,roughlycharacterizesthecurrentresponsesbetween10.435s[Figure3a(iv)],whileittook0.074sfromt=51.374bresistiveorconductive.Especiallyforλ>anb/(3n′),thes[Figure3d(vi)]tot=51.448s[Figure3d(viii)].Therefore,currentresponsewillbeconductive,whichtendstobesatisfiedthetransportwassymmetricbetweenforwardandbackwardbysmallaandlargen′comparedtonb.Furthermore,thedirectionsinthesamepathway.However,therewasasmalldirectionofparticletransport,forwardorbackward,toEOFserrorbecausethecircularorbitalmotionwasnotcompletelycanbeelectricallyinvestigatedbyusinganopticalvortexandahomogeneous.TheangularvelocityoftheAuNPshowedadouble-slitstructure,asshowninFigure2c.positiondependency.Theeffectcausedbytheimperfectionof9509https://doi.org/10.1021/acs.jpcc.1c01804J.Phys.Chem.C2021,125,9507−9515

3TheJournalofPhysicalChemistryCpubs.acs.org/JPCCArticleFigure3.ExperimentalresultsfromopticalobservationsandioniccurrentmeasurementsofaAuNPmanipulatedbyanopticalvortexwiththetopologicalchargeofm=3(a−c)andm=−3(d−f)using2×PBS.(a)SnapshotsofaAuNPmovingaroundthecenterpostofthedoublenanoslitintheclockwisedirection,(b)ioniccurrentresponsecorrespondingto(a),and(c)focusedviewbetweent=10.0and11.0sin(b)form=3.(d)Snapshotsinthecounterclockwisedirection,(e)ioniccurrentresponsecorrespondingto(d),andfocusedviewbetweent=51.0and52.0sin(f)form=−3.opticalvorticesontheparticlemotionswasalsodiscussedinaobtainedatslitAandslitB,respectively.Theconductivepeak33previousstudy.Ontheotherhand,theopticalmanipulationatslitAwasevaluatedasΔIc=166pAandtheresistiveoneaterrorsdidnotcauseaseriousproblemintheelectricalslitBwasΔIr=−28pA,wherethebaselinecurrentwasmeasurements.determinedbythecurrentvalueobtainedattheintermediateDuetothecircularorbitalmotionofthetargetparticle,wepositionofthetrajectory.Form=−3,asshowninFigure4b,couldobtainmultiplesignalsfromasingleparticleandcouldweobtainedaconductivepulseofΔIc=132pAatslitBandasynchronouslyaverage154pulses.Asaresult,thesignal-to-resistiveoneofΔIr=−30pAatslitA.AsdescribedinFigurenoiseratiowasimprovedby10times.Figure4showsresults3,thesignofcurrentpulseswasreversedwithrespecttothefromthesynchronousaverageofcurrentpulsesforaperiodofsignofmthatcausedclockwiseorcounterclockwisemotions.0.4sforthecasesofm=3(Figure4a)andm=−3(FigureSomereasonswhythecurrentpulsedependsonthedirection4b);schematicillustrationsforthephenomenacorrespondingoftheparticlemotionareconsidered.Theconductivepeakstom=3(Figure4c)andm=−3(Figure4d).Form=3,aswereobtainedwhentheparticlepassedthroughtheslitalongshowninFigure4a,conductiveandresistivepeaksweretheelectricfield.Inthepresentexperiment,anelectric9510https://doi.org/10.1021/acs.jpcc.1c01804J.Phys.Chem.C2021,125,9507−9515

4TheJournalofPhysicalChemistryCpubs.acs.org/JPCCArticleFigure4.Synchronouslyaveragedcurrentwaveformsfor(a)m=3and(b)m=−3usingexperimentaldatainFigure3.(a)AconductivepulserecognizedatslitAisΔIc=166pAaverageandaresistivepulseatslitBisΔIr=−28pAaverageform=3.(b)AconductivepulseatslitBisΔIc=132pAaverageandaresistivepulseatslitAisΔIr=−30pAform=−3.(c,d)RelationshipbetweenthetransportdirectionofaAuNPandioniccurrentwithrespectto(c)m=3and(d)m=−3.Figure5.(a)SnapshotsofthecircularorbitalmotionofaAuNPform=3and(b−d)correspondingioniccurrentresponses,wherethelaserirradiationwasturnedoffatt=49.920s.Ina0.5×PBSsolution,(a)aAuNPwasdrivenbytheopticalvortexfromt=49.894to49.912sandtheparticletranslocationwasfreefromtheopticalvortexfromt=49.920to51.042s,whichpassedthroughtheslitsat(i)t=49.894s,(iii)49.912s,and(vi)50.956s.(b)Ioniccurrentresponsecorrespondingto(a).(c,d)Magnifiedviewof(b)betweent=49.80and50.00s(c)andbetweent=50.80and51.12s(d).potentialof0.1Vwasappliedattheleftreservoirrelativetopossiblyinducesioniccurrentrectification,andinsuchatherightone,andthen,theelectricfieldwasdirectedfromthecondition,anEOFwillbeinducedbythecationiccurrentthatlefttotheright.Theheightofthefluidicchannel(350nm)isantisymmetrictothedirectionofparticletransportbetween9511https://doi.org/10.1021/acs.jpcc.1c01804J.Phys.Chem.C2021,125,9507−9515

5TheJournalofPhysicalChemistryCpubs.acs.org/JPCCArticleFigure6.SchematicdiagramofioniccurrentresponsescausedbyaAuNPinthenanoslitfor(a,b)m=3and(c,d)m=−3.(a,b)AAuNPwiththevelocityv0isinthesamedirectionasEOFwithu0atthewallsurfacein(a)lowand(b)highconcentrations.(c,d)ThetransportofaAuNPwithu0isoppositetoEOFwithu0atthewallsurfacein(c)lowand(d)highconcentrations.Intheexperiments,resistivepulseswereobservedfortheconditionof(d),otherwiseconductive.slitAandslitB.Recently,thiskindofioniccurrentsolution,SandLarethecross-sectionalareaandthelengthofrectificationhasalsobeenreportedbysomeresearchananochannel,respectively,listheperimeterofS,thecharge45−47groups.Itwasfoundthattheioniccurrentincreaseddensityofthecounterionρi(x)isintegratedintheEDL,andηiwhenaparticlepassedthroughaslitalongtheEOFand,onisthemobilityofthecounterion.ρiisdefinedbythetheotherhand,decreasedagainsttheEOF,asschematicallyBoltzmanndistributionatanequilibriumconditionasfollows:illustratedinFigure4c,d.Itissuggestedthatanegativelyρi=ρ0exp[−zieϕ/(kBT)],whereϕistheelectrostaticpotentialchargedAuNP,whichisforcedtomoveintoanarrowslitandρ0istheconstantdeterminedbythebulknumberdensity,whosesurfacesarealsonegativelycharged,stronglyattractssuchthatρ0=zienb,whereziisthevalenceandeisthecationstoscreenthehighlyconcentratednegativechargesinelementarycharge.ϕ(x)isobtainedbysolvingthePoissontheslit.Thiscausesanincreaseintheconductivitythatequationasfollows:−εrε0Δϕ=∑kρk.Forthesurfacepotentialdependsontheionconcentration.Theioniccurrentϕs,assumingmonovalentionsande|ϕs|

6TheJournalofPhysicalChemistryCpubs.acs.org/JPCCArticle−3,itwasclarifiedthattheioniccurrentresponsesreflectedcenter,comparedtoionssweptout(Figure6c).Inthiscase,therelativedirectiondifferencebetweentheappliedelectrictheconductiveeffectpossiblybecomesdominant.OnthefieldorEOFandtheparticletransport.InFigure4,conductiveotherhand,surfacesofaAuNPandwallsurfacessufficientlypulseswerefoundwhenaAuNPfollowedtheelectricfields,screenedinhigh-concentrationsolutionsmaynotenhancetheandontheotherhand,resistivepulseswerefoundwhenaAuioniccurrentenoughtoshowconductivepulsesthatexceedNPwasagainsttheelectricfieldsina2×PBSsolution.Inthevolumeexclusion(Figure6d).ThepresentresultsareFigure5,conductivepulseswereobservedatbothslitsinatypicalforopticallytrappedAuNPsbecauseconductivepulses0.5×PBSsolution,wherethecurrentpeaksofthefollowinghaveneverbeenobtainedfromthesimilarexperimentsusingdirectionwerealsolargerthanthoseofthereversedirection.It16polystyreneparticles.Itwasindicatedthattheabsorptionisimpliedthatexcesschargesthatcontributetoioniccurrentefficiencyofpolystyreneparticlestoa1064nmwavelengthwasresponsesareinducedbyanopticallymanipulatedAuNP.ThemuchsmallerthanthatofAuNPsandthattheheatingeffectsresponsestendtobecomeconductivewithdecreasing48describedabovewerenotexpectedforpolystyreneparticles.electrolyteconcentrationsbeingovertheresistivefactorof55,56BazantandSquiressuggestthationiccloudssurround-thevolumeexclusioneffect.ThistendencyagreeswithingaAuNPrespondtoelectricfieldsassociatedwiththe4339,42previousreportsbySmeetsetal.andtheothergroups.polarizationofAuNP,whichalsopossiblymodulatesionicEquation2indicatesthatthebulkconductivityσdecreasescurrentsandEOFs.Theytheoreticallyandexperimentallyproportionallytotheionconcentration,andΔGAuNPrelativelyinvestigatedinduced-chargeelectroosmosisandinduced-becomesprominent.However,thedetailofΔGAuNPasachargeelectrophoresisofasymmetricmetallicparticlesexposedfunctionoftheconcentrationexposedtoanopticalvortexhastoDCandACelectricfields.Inpreviousstudies,wealsoremainedtobeclarifiedinthefuture.Figure6schematicallydiscussedchargeinductioneffectsthatdroveelectrohydrody-summarizesthepresentexperimentalresultstorepresentthenamicflowsofliquids.57,58Thepresentstudyprovidespossibilitiesofconductiveandresistivepulses,focusingontheexperimentalresultsthatsuggestedsomepossibilitiesofioniccaseofm=3.FlowprofilesatanarrowgapbetweenaAuNPcurrentandflowcharacteristicsinducedbyAuNPsattheandchannelwallsurfaceatslitA(Figure6a,b)andslitBnanoscale,andfurtherdetailswillbeclarifiedinthefuture.(Figure6c,d)areillustrated.AtslitA,asshowninFigure6a,b,thetransportvelocityofaAuNP,v0,isinthesamedirectionas■theEOFvelocity,u0,atthewallsurface,inducedbyanappliedCONCLUSIONSelectricfieldE.Figure6a,brepresentsthecasesoflowandhighInthisstudy,electricalsensingofsingleAuNPswaselectrolyteconcentrations,respectively.Inbothcases,theflowdemonstratedusingadouble-nanoslitstructureexposedtodirectionisalongtheelectrophoretictransportofcations.Inanopticalvortexofnear-infraredlight,whereaAuNPwasthesecases,theioniccurrentresponsepossiblybecomesdrivenintoacircularorbitalmotionaroundacenterpostconductiveifexcesscationsmorethantheexcludedionsarebetweentwoslits.Underioniccurrentconditions,electricalbroughtintothenanoslitbyaAuNP.Intheexperiments,wesignalswerefinelyshapedbysynchronouslyaveragingthealwaysobtainedconductivepulseswhenaAuNPmovedalongrepetitivelyaccumulatedsignalsandthesignal-to-noiseratiotheelectricfieldregardlessofthesaltconcentration.Aswasimprovedby10times.Asaresult,highthroughputof48single-particleanalysiswasachieved.TheopticalobservationcarefullyinvestigatedbyBendixetal.,theyreportedthatanirradiatedAuNPwithadiameterof200nmwasheatedandclarifiedthatelectricalsignalsshowedconductiveorresistivethesurfacetemperaturepossiblyreachedabout150Khigherpulsesaccordingtotherelationshipbetweentheparticlethanthoseofsurroundingliquidsatalaserpowerof100mW.transportdirectionandtheelectricfieldintheslit.ItwasalsoItissuggestedthatAuNPsirradiatedbyfocusedlaserbeamsfoundthatanopticallymanipulatedAuNPenhancedtheionic49−51tendtobeheatedandthattemperatureincreasemainlycurrentandresultedinaconductivepulsethatexceededthe52,53decreasestheviscosity.Furthermore,heatinginthenarrowresistivecomponentofvolumeexclusion.ExcesscounterionsspacewillmodulateiondistributionsneartheparticleandalsowerebroughtintotheslitbyanegativelychargedAuNPthat54increasestheconductivityofelectrolytesolutions.Accordingwasheatedbyanopticalvortex,andthisforcedconditiontotheBoltzmanndistribution,thecounteriondistributionwillenhancedtheioniccurrent,increasingtheconductivity.bebroadenedwiththetemperatureincreaseandthesurfacepotentialofAuNPbecomeswidelyeffectivetoattract■ASSOCIATEDCONTENTcounterionsfromfarareas.Thiswillincreasetheconductivity.Itwasalsofoundthattheopticalvortexwasinevitableto*sıSupportingInformationobtaintheconductivepulses.ThisisapossiblereasonwhytheTheSupportingInformationisavailablefreeofchargeatconductivepulsesareexperimentallyobtainedatslitAform=https://pubs.acs.org/doi/10.1021/acs.jpcc.1c01804.3.Onthecontrary,Figure6c,ddenotessituationsinwhichaContinuousclockwiseandcounterclockwisetransportofAuNPandEOFareoppositelydirectedforlowandhighaAuNP(MP4)electrolyteconcentrations,respectively.Inbothcases,thetransportofaAuNPcausestodragcationsagainsttheelectricfield.Takingthevolumeexclusionintoaccount,resultsfrom■botheffectssuchastheinductionofcationsanddragagainstEAUTHORINFORMATIONbytheAuNPwilldeterminetheconductiveorresistiveCorrespondingAuthorresponses.Asmentionedabove,althoughaheatedAuNPSatoyukiKawano−DepartmentofMechanicalScienceandinducescationsintheslit,whichcauseconductiveionicBioengineering,GraduateSchoolofEngineeringScience,responses,thereversemotionsuppressestheioniccurrent,OsakaUniversity,Toyonaka,Osaka560-8531,Japan;involvingtheliquidflow.Especiallyforthelow-concentrationPhone:+81668506175;Email:kawano@me.es.osaka-case,aheatedAuNPmayattractexcesscationsfarfromtheu.ac.jp;Fax:+816685061759513https://doi.org/10.1021/acs.jpcc.1c01804J.Phys.Chem.C2021,125,9507−9515

7TheJournalofPhysicalChemistryCpubs.acs.org/JPCCArticleAuthors(12)Zangle,T.A.;Mani,A.;Santiago,J.G.TheoryandExperimentsRyojiNakatsuka−DepartmentofMechanicalScienceandofConcentrationPolarizationandIonFocusingatMicrochannelandBioengineering,GraduateSchoolofEngineeringScience,NanochannelInterfaces.Chem.Soc.Rev.2010,39,1014−1035.OsakaUniversity,Toyonaka,Osaka560-8531,Japan(13)Qian,W.;Doi,K.;Kawano,S.EffectsofPolymerLengthandSaltConcentrationontheTransportofssDNAinNanofluidicSyuheiYanai−DepartmentofMechanicalScienceandChannels.Biophys.J.2017,112,838−849.Bioengineering,GraduateSchoolofEngineeringScience,(14)Yasaki,H.;Yasui,T.;Yanagida,T.;Kaji,N.;Kanai,M.;OsakaUniversity,Toyonaka,Osaka560-8531,JapanNagashima,K.;Kawai,T.;Baba,Y.SubstantialExpansionofKichitaroNakajima−GlobalCenterforMedicalEngineeringDetectableSizeRangeinIonicCurrentSensingThroughPoresbyandInformatics,OsakaUniversity,Suita,Osaka565-0871,UsingaMicrofluidicBridgeCircuit.J.Am.Chem.Soc.2017,139,Japan;orcid.org/0000-0003-2644-741X14137−14142.KentaroDoi−DepartmentofMechanicalEngineering,(15)Nito,F.;Shiozaki,T.;Nagura,R.;Tsuji,T.;Doi,K.;Hosokawa,ToyohashiUniversityofTechnology,Toyohashi,Aichi441-C.;Kawano,S.QuantitativeEvaluationofOpticalForcesbySingle8580,Japan;orcid.org/0000-0002-2663-9369ParticleTrackinginSlit-LikeMicrofluidicChannels.J.Phys.Chem.C2018,122,17963−17975.Completecontactinformationisavailableat:(16)Doi,K.;Nito,F.;Koyama,R.;Kawano,S.RepetitiveElectricalhttps://pubs.acs.org/10.1021/acs.jpcc.1c01804SensingofOpticallyTrappedMicroparticlesinMotorizedLiquidFlows.J.Phys.Chem.C2020,124,10627−10637.AuthorContributions(17)Grier,D.G.ARevolutioninOpticalManipulation.NatureThepresentstudywasadministratedbyK.D.andS.K.;the2003,424,810.experimentalmethodologywasdevelopedandcarriedoutby(18)Neuman,K.C.;Block,S.M.OpticalTrapping.Rev.Sci.R.N.,S.Y.,andK.N.;andthemanuscriptwaswrittenbyR.N.,Instrum.2004,75,2787−2809.K.N.,K.D.,andS.K.(19)Marago,O.M.;Jones,P.H.;Gucciardi,P.G.;Volpe,G.;̀Ferrari,A.C.OpticalTrappingandManipulationofNanostructures.NotesNat.Nanotechnol.2013,8,807−819.Theauthorsdeclarenocompetingfinancialinterest.(20)Ashkin,A.AccelerationandTrappingofParticlesbyRadiationPressure.Phys.Rev.Lett.1970,24,156−159.■(21)Ashkin,A.;Dziedzic,J.M.OpticalLevitationbyRadiationACKNOWLEDGMENTSPressure.Appl.Phys.Lett.1971,19,283−285.ThisstudywassupportedinpartbytheGrant-in-Aidfor(22)Ashkin,A.;Dziedzic,J.M.;Bjorkholm,J.E.;Chu,S.ScientificResearch(S)JSPSKAKENHIgrantno.ObservationofaSingle-BeamGradientForceOpticalTrapforJP18H05242,ScientificResearch(B)JSPSKAKENHIgrantDielectricParticles.Opt.Lett.1986,11,288−290.no.JP18H01372,andtheScientificResearchonInnovative(23)Ashkin,A.ForcesofaSingle-BeamGradientLaserTraponaAreas“Nano-MaterialOptical-Manipulation”JSPSKAKENHIDielectricSphereintheRayOpticsRegime.Biophys.J.1992,61,grantno.JP16H06504.569−582.(24)Liu,Y.;Sonek,G.J.;Berns,M.W.;Tromberg,B.J.■PhysiologicalMonitoringofOpticallyTrappedCells:AssessingtheREFERENCESEffectsofConfinementby1064-nmLaserTweezersUsingMicro-(1)Howorka,S.;Cheley,S.;Bayley,H.Sequence-SpecificDetectionfluorometry.Biophys.J.1996,71,2158−2167.ofIndividualDNAStrandsUsingEngineeredNanopores.Nat.(25)Applegate,R.W.,Jr;Squier,J.;Vestad,T.;Oakey,J.;Marr,D.Biotechnol.2001,19,636−639.W.M.OpticalTrapping,Manipulation,andSortingofCellsand(2)Keyser,U.F.;Koeleman,B.N.;VanDorp,S.;Krapf,D.;Smeets,ColloidsinMicrofluidicSystemswithDiodeLaserBars.Opt.ExpressR.M.M.;Lemay,S.G.;Dekker,N.H.;Dekker,C.DirectForce2004,12,4390−4398.MeasurementsonDNAinaSolid-StateNanopore.Nat.Phys.2006,2,(26)Shoji,T.;Tsuboi,Y.PlasmonicOpticalTrappingofSoft473−477.NanomaterialsSuchasPolymerChainsandDNA:Micro-Patterning(3)Dekker,C.Solid-StateNanopores.Nat.Nanotechnol.2007,2,Formation.Opt.Rev.2015,22,137−142.209−215.(27)Fällman,E.;Axner,O.InfluenceofaGlass-WaterInterfaceon(4)Branton,D.;etal.ThePotentialandChallengesofNanoporetheOn-AxisTrappingofMicrometer-SizedSphericalObjectsbySequencing.Nat.Bioltechnol.2008,26,1146−1153.OpticalTweezers.Appl.Opt.2003,42,3915−3926.(5)Zwolak,M.;DiVentra,M.Colloquium:PhysicalApproachesto(28)Kudo,T.;Wang,S.-F.;Yuyama,K.-i.;Masuhara,H.OpticalDNASequencingandDetection.Rev.Mod.Phys.2008,80,141−165.Trapping-FormedColloidalAssemblywithHornsExtendedtothe(6)Clarke,J.;Wu,H.-C.;Jayasinghe,L.;Patel,A.;Reid,S.;Bayley,OutsideofaFocusthroughLightPropagation.NanoLett.2016,16,H.ContinuousBaseIdentificationforSingle-MoleculeNanopore3058−3062.DNASequencing.Nat.Nanotechnol.2009,4,265−270.(29)Toyoda,K.;Miyamoto,K.;Aoki,N.;Morita,R.;Omatsu,T.(7)Tsutsui,M.;Taniguchi,M.;Yokota,K.;Kawai,T.IdentifyingSingleNucleotidesbyTunnellingCurrent.Nat.Nanotechnol.2010,5,UsingOpticalVortextoControltheChiralityofTwistedMetal286−290.Nanostructures.NanoLett.2012,12,3645−3649.(8)Ohshiro,T.;Matsubara,K.;Tsutsui,M.;Furuhashi,M.;(30)Sakai,K.;Nomura,K.;Yamamoto,T.;Sasaki,K.ExcitationofTaniguchi,M.;Kawai,T.Single-MoleculeElectricalRandomMultipolePlasmonsbyOpticalVortexBeams.Sci.Rep.2015,5,8431.ResequencingofDNAandRNA.Sci.Rep.2012,2,501.(31)Kimura,Y.HydrodynamicallyInducedCollectiveMotionof(9)Houghtaling,J.;List,J.MayerNanopore-Based,M.RapidOpticallyDrivenColloidalParticlesonaCircularPath.J.Phys.Soc.CharacterizationofIndividualAmyloidParticlesinSolution:Jpn.2017,86,101003.Concepts,Challenges,andProspects.Small2018,14,No.e1802412.(32)Saito,K.;Okubo,S.;Kimura,Y.ChangeinCollectiveMotion(10)Tsutsui,M.;Yokota,K.;Yoshida,T.;Hotehama,C.;Kowada,ofColloidalParticlesDrivenbyanOpticalVortexwithDrivingForceH.;Esaki,Y.;Taniguchi,M.;Washio,T.;Kawai,T.IdentifyingSingleandSpatialConfinement.SoftMatter2018,14,6037−6042.ParticlesinAirUsinga3D-IntegratedSolid-StatePore.ACSSens.(33)Tsuji,T.;Nakatsuka,R.;Nakajima,K.;Doi,K.;Kawano,S.2019,4,748−755.Effectofhydrodynamicinter-particleinteractionontheorbital(11)Schoch,R.B.;Han,J.;Renaud,P.TransportPhenomenainmotionofdielectricnanoparticlesdrivenbyanopticalvortex.Nanofluidics.Rev.Mod.Phys.2008,80,839−883.Nanoscale2020,12,6673−6690.9514https://doi.org/10.1021/acs.jpcc.1c01804J.Phys.Chem.C2021,125,9507−9515

8TheJournalofPhysicalChemistryCpubs.acs.org/JPCCArticle(34)Allen,L.;Beijersbergen,M.W.;Spreeuw,R.J.C.;Woerdman,(56)Bazant,M.Z.;Squires,T.M.Induced-ChargeElectrokineticJ.P.OrbitalAngularMomentumofLightandtheTransformationofPhenomena.Curr.Opin.ColloidInterfaceSci.2010,15,203−213.Laguerre-GaussianLaserModes.Phys.Rev.A:At.,Mol.,Opt.Phys.(57)Doi,K.;Yano,A.;Kawano,S.ElectrohydrodynamicFlow1992,45,8185.througha1mm2Cross-SectionPorePlacedinanIon-Exchange(35)Harada,Y.;Asakura,T.RadiationForcesonaDielectricSphereMembrane.J.Phys.Chem.B2015,119,228−237.intheRayleighScatteringRegime.Opt.Commun.1996,124,529−(58)Doi,K.;Nito,F.;Kawano,S.Cation-InducedElectro-541.hydrodynamicFlowinAqueousSolutions.J.Chem.Phys.2018,(36)Ng,J.;Lin,Z.;Chan,C.T.TheoryofOpticalTrappingbyan148,204512.OpticalVortexBeam.Phys.Rev.Lett.2010,104,103601.(37)Nagura,R.;Tsujimura,T.;Tsuji,T.;Doi,K.;Kawano,S.Coarse-GrainedParticleDynamicsalongHelicalOrbitbyanOpticalVortexIrradiatedinPhotocurableResins.OSAContinuum2019,2,400−415.(38)Feng,J.;Liu,K.;Bulushev,R.D.;Khlybov,S.;Dumcenco,D.;Kis,A.;Radenovic,A.IdentificationofsinglenucleotidesinMoS2nanopores.Nat.Nanotechnol.2015,10,1070−1076.(39)Goyal,G.;Freedman,K.J.;Kim,M.J.GoldNanoparticleTranslocationDynamicsandElectricalDetectionofSingleParticleDiffusionUsingSolid-StateNanopores.Anal.Chem.2013,85,8180−8187.(40)Zhe,J.;Jagtiani,A.;Dutta,P.;Hu,J.;Carletta,J.AMicromachinedHighThroughputCoulterCounterforBioparticleDetectionandCounting.J.Micromech.Microeng.2007,17,304.(41)Edwards,M.A.;German,S.R.;Dick,J.E.;Bard,A.J.;White,H.S.High-SpeedMultipassCoulterCounterwithUltrahighResolution.ACSNano2015,9,12274−12282.(42)Chang,H.;Kosari,F.;Andreadakis,G.;Alam,M.A.;Vasmatzis,G.;Bashir,R.DNA-MediatedFluctuationsinIonicCurrentThroughSiliconOxideNanoporeChannels.NanoLett.2004,4,1551−1556.(43)Smeets,R.M.M.;Keyser,U.F.;Krapf,D.;Wu,M.-Y.;Dekker,N.H.;Dekker,C.SaltDependenceofIonTransportandDNATranslocationThroughSolid-StateNanopores.NanoLett.2006,6,89−95.(44)Kawaguchi,C.;Noda,T.;Tsutsui,M.;Taniguchi,M.;Kawano,S.;Kawai,T.ElectricalDetectionofSinglePollenAllergenParticlesUsingElectrode-EmbeddedMicrochannels.J.Phys.:Condens.Matter2012,24,164202.(45)Vlassiouk,I.;Siwy,Z.S.NanofluidicDiode.NanoLett.2007,7,552−556.(46)Guan,W.;Fan,R.;Reed,M.A.Field-EffectReconfigurableNanofluidicIonicDiodes.Nat.Commun.2011,2,506.(47)Lin,C.-Y.;Wong,P.-H.;Wang,P.-H.;Siwy,Z.S.;Yeh,L.-H.Electrodiffusioosmosis-InducedNegativeDifferentialResistanceinpH-RegulatedMesoporesContainingPurelyMonovalentSolutions.ACSAppl.Mater.Interfaces2020,12,3198−3204.(48)Bendix,P.M.;Reihani,S.N.S.;Oddershede,L.B.DirectMeasurementsofHeatingbyElectromagneticallyTrappedGoldNanoparticlesonSupportedLipidBilayers.ACSNano2010,4,2256−2262.(49)Govorov,A.O.;Richardson,H.H.GeneratingHeatwithMetalNanoparticles.Nanotoday2007,2,30−38.(50)Pelaz,B.;Grazu,V.;Ibarra,A.;Magen,C.;delPino,P.;delaFuente,J.M.TailoringtheSynthesisandHeatingAbilityofGoldNanoprismsforBioapplications.Langmuir2012,28,8965−8970.(51)Hashimoto,S.;Werner,D.;Uwada,T.StudiesontheInteractionofPulsedLaserswithPlasmonicGoldNanoParticlesTowardLightManipulation,HeatManagement,andNanofabrication.J.Photochem.Photobiol.,C2012,13,28−54.(52)Peterman,E.J.G.;Gittes,F.;Schmidt,C.F.Laser-InducedHeatinginOpticalTraps.Biophys.J.2003,84,1308−1316.(53)Seol,Y.;Carpenter,A.E.;Perkins,T.T.GoldNanoparticles:EnhancedOpticalTrappingandSensitivityCoupledwithSignificantHeating.Opt.Lett.2006,31,2429−2431.(54)Wu,Y.C.;Koch,W.F.AbsoluteDeterminationofElectrolyticConductivityforPrimaryStandardKClSolutionsfrom0to50°C.J.SolutionChem.1991,20,391−401.(55)Squires,T.;Bazant,M.BreakingSymmetriesinInduced-ChargeElectro-OsmosisandElectrophoresis.J.FluidMech.2006,560,56−101.9515https://doi.org/10.1021/acs.jpcc.1c01804J.Phys.Chem.C2021,125,9507−9515