facile tuning of the mechanical properties of a biocompatible soft material daniele vigolo资料.pdf

该【facile tuning of the mechanical properties of a biocompatible soft material daniele vigolo资料 】是由【赖大文档】上传分享，文档一共【7】页，该文档可以免费在线阅读，需要了解更多关于【facile tuning of the mechanical properties of a biocompatible soft material daniele vigolo资料 】的内容，可以使用淘豆网的站内搜索功能，选择自己适合的文档，以下文字是截取该文章内的部分文字，如需要获得完整电子版，请下载此文档到您的设备，方便您编辑和打印。entificreportsOPENFaciletuningofthemechanicalpatiblesoftmaterialReceived:26November2018Daniele?Vigolo??1,3,Shivaprakash?N.?Ramakrishna2&Andrew?J.?deMello1Accepted:27April2019Herein,weintroduceamethodtolocallymodifythemechanicalpropertiesofasoft,patiblePublished:,-layermicrofuidicdevice,,ournovelapproachenablesthecreationofsteepgradientsinmechanicalproperties(typicallybetween10–100kPa/mm)onsmallscales,–,unveilinghowmigration4–6,proliferation6,7,adhesion5,8andalsodiferentiation7,9,,patiblematerialspossessingarigiditygra-dient11–,forexample,fortheosteotendinousinsertion,thetissueformedbydiferentiationsofMesenchymalStemCells(MSCs)-,controlovertheYoung’,weshowforthefrsttimethecreation,,-essibilityofformationmethodolo-,bothissuesarecloselyrelated,,therigidityofagelcanbetunedbycontrollingthedegreeofcrosslinkingortheinitialmono-,theuseofanopticalmaskcontainingaspatialgradientintransparencycanbeusedtocontrollightintensityduringthephoto-,amicrofuidicgradientgenerator15andaphoto-polymerizationstepcanbeusedto“fx”adesiredconcentrationgradientwithinamate-,themainlimitationsofsuchtechniquesrelatetothechoiceofthesubstratematerial,whichisrestrictedtoUVcurablepolymers,,uratelyimposeandcontrolpatiblematerialpresent-ingarigiditygradient,,DepartmentofChemistryandAppliedBiosciences,ETHZurich,VladimirPrelogWeg1,Zürich,8093,,DepartmentofMaterials,ETHZürich,Vladimir-Prelog-Weg5,CH-8093,Zürich,:SchoolofChemicalEngineering,UniversityofBirmingham,Edgbaston,Birmingham,B152TT,.(email:d.******@)ScientificReports|(2019)9:7125|https:///-019-43579-81entificreports/entificreportsthepresenceofatemperaturegradient,?,sincethermophoresiscanbeappliedtoanykindofsolutedispersedinsolu-tion,thebasicmethodcanbeeasilyextendedtoanypolymerorhydrogelundergoingapolymerizationorsol-,,thepatiblehydrogelusingonlyminutetemperaturediferencesthatdonotaltertheoverallpropertiesofthematerialandthen,independently,,,inthepresenceofatemperaturegradient,umulateeitheronthe‘cold’orthe‘hot’sidedependingonthespecifcsolute-solventinteractions18,averagetemperature19,20,-state,themassfux,Jm,iszeroandtheconcentrationgradientiscounterbalancedbythetemperaturegradient(Eq.?1),wherethegradientisassumedtobealongthez-axis,.?dcdT?JDmT=ρ???cc(1)D???dzdz??dcdTJmT=→0(=?cc1)?Sdzdz(1)here,ρisthedensityofthesolute,cistheconcentration,Disthedifusioncoefcient,DTisthethermopho-reticmobilityandSTthesocalledSoretcoefcient,equaltoDT/,theSoretcoefcientispos-ursonthehigh-,asaconsequence,atsmallscalestypicalofmicrofuidicdevices,onlyaverylimitedtemperaturediferenceisrequiredpatiblematerialtogeneratetherequiredmechanicalpropertiesgradient,-tionofmonomers,-ortri-valentions(+,Fe3+andAl3+)23canthenbeusedto“fx”,tem-peraturegradientscanbeeasilygeneratedandcontrolledwithinmicrofuidicenvironments(forexamplebyembeddingJouleheaters24–26),.?Aspreviouslynoted,theconcentrationgra-dientmaterialwasformedinatwo-layerPDMS(polydimethylsiloxane),adispersionof80?nmdiametercalciumcar-bonatenanoparticlesand200?nmdiameterpolystyrenebeads(usedtovisualizethehydrogel)″?×?″ODTygonmicroboretubing(Cole-.,UK)intoa600?μmwideand70?μm(or140?μm)-pletelystopped,atransversetemperaturegradientwasthenimposedbyexploitingthepresenceoftwolargerparallelchannels(2?mmwide)(LMPA)heatedaboveitsmeltingtemperature(toallowentry),coldwaterwasmotivatedatavolumetricfowrateinexcessof300?μL/?mmwideand140?μmthickmicrochannelwasalignedwiththeprimarymicrochannelinthefrstlayer(Fig.?1)andflledwithanacidicoilsolution(aceticacid5%v/vinsoybeanoil).Difusionthroughthemembrane,providesanefcientroutetoloweringthepHofthesampleanddissolvingthecalciumcarbonatenanoparticlesthatfreeCa2+,weperformedaseriesofexperimentsatdiferentaveragetemperatures,whilstmaintainingatransversaltemperaturegradientofbetween0and8?°C/mmacrossthemicrochannelcontainingthesodiumalginatesolutionforbetween20and60?,inducedbytheacidicoilsolution,tookplacewithin2to5?minutes,withthecalciumalginatehydrogelbeingeas-,,?°CpriortoAFMnano-,D,beingthelatterproportionaltoitscharacteristicsizeviatheStokes-Einsteinequation,ScientificReports|(2019)9:7125|https:///-019-43579-82entificreports/entificreportsFigure1.?Deviceschematic.(a)Schematicofthetwo-layerdevice.(b)Teworkingprinciplebehindthermophoresis:atemperaturegradientisimposedtransversallyinthechannel,withsodiumalginatemoleculesmigratingalongthetemperaturegradientandgeneratingaconcentrationgradientresponsible,whichinturnpatiblematerial.(c)=,6πηRwherekistheBoltzmannconstant,Tthetemperature,,(havinganaveragediameterof200?nm)?nm(weestimatedthealginatemoleculesizeusedinourexperimentstobebetween5and7?nm–seeESIformoredetails),,theaveragetimerequiredforthepoly-styreneparticlestostarttodrifappreciablywithinthetemperaturegradientwas45?minutes(Fig.?S1).Byensur-ingthatallmeasurementswereperformedbeforethischaracteristictime,,,theminimumtimeforthecalciumcarbonateparticletomigratecanbeestimatedasthecalculatedminimumtimerequiredforthepolystyreneparticlestomigratetimesRCaCO3/RPS,whereRCaCO3istheradiusofthecalciumcarbonateparticles(40?nm)andRPS,istheradius?ofthepolystyreneparticles(100?nm).Asaresult,forexperimentsshorterthan18?minutesonlysodiumalginatemoleculesareresponsiblefortheconcentra-tiongradientandsoforthestifnessgradient,forlongerexperimentsaweakconcentrationgradientofcalciumcar-,oncethecalciumcarbonatenanoparticlesaredissolved,alsotheCa2+ionswillbeafectedbythetemperaturegradientandwilleventuallycre-?minutestomigratewhiletheviscosityisincreasingduetotheongoingcrosslinkingprocess,,duetothepossibilityofan“ioncageefect”inducedbythesodiumalginatemolecules,-nent,ourresultsdemonstratedthatthestifnessgradientissolelydependenton(andproportionalto)themagni-tudeofthetemperaturegradientimposedandtheaveragetemperature(seeFig.?3bwherewealsoshowedthatanidenticalmaterialgeneratedatuniformtemperaturedoesnotpresentastifnessgradient).Tocharacterizediferingthermalconditionsandrelativeconcentrationgradients,temperaturemustbemon-,weadoptedanindirectmethod,wherethetemperaturemeasuredbesidetheheaterandcoolerwasusedtoestimatetheactualtemperatureofthesampleusingcalibrationmeasurementsobtainedfromadummydevice,inwhichthePDMSmembraneissubstitutedbyaglasscoversliptoimprovethermalconductivity(Fig.?2).Additionally,,Massachusetts,USA)toevaluatethecross-sectionaldistributionoftemperatureinthemiddleplaneofthedevice(Fig.?2).ScientificReports|(2019)9:7125|https:///-019-43579-83entificreports/ent