刘晓辉文献综述汇报.ppt
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刘晓辉文献综述汇报.ppt
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报告人:
刘晓辉2013年4月21日,本综述主要内容:
本综述是郑南峰课题组刚刚在Nanoscale上发表题为Self-templatingsynthesisofhollowmesoporoussilicaandtheirapplicationsincatalysisanddrugdelivery的综述文章综述了空心介孔二氧化硅(包括yolk/shell结构)的合成及应用。
合成方面着重强调了自身模板法,包括表面保护-腐蚀法、基于结构差异的选择性腐蚀法以及阳离子表面活性剂辅助自模板法等三大类。
应用方面则主要介绍了催化和药物传输方面的应用。
Hollowmesoporoussilicamaterialshavebeenintensivelypursuedbecauseoftheiruniquepropertiesforvariousapplications.Yolk/shellstructuredhollowmesoporoussilicawithfunctionalcoresinsidetheirhollowinteriorcanfurtherbroadentheapplicationsofhollowmesoporoussilica.Self-templatingstra-tegyhasbeendevelopedasoneofthemostimportantstrategiestoeffectivelyfabricatehollowmesoporoussilicaandtheiryolk/shellcounterparts.Inthisfeaturearticle,weprovideanoverviewofadvancesinself-templatingsynthesisofhollowmesoporoussilicabasedonthefollowingthreestrategies:
surface-protectedetching,structuraldifference-basedselectiveetching,andcationicsurfac-tantassistedself-templating.Wethendiscusssomeimportantapp-licationsoftheseself-templatingstrategiesderivedhollowmesoporoussilica,suchasnanoreactorsforconfinedcatalysisandmultifunctionalplatformforcombinedtherapy.Finally,someperspectivesforthefuturedevelopmentofthisactiveresearchfieldareprovided.,Abstract,1.Introduction,1.Hollowstructuresarehighlyattractiveinbothfundamentalresearchandpracticalapplications.2.Uptodate,templatingmethodisprobablythemosteffectiveandgeneralroutetoprepareHMS.Incomparison,asanevidentadvantageofhard-templatingmethods,theshapeandcavitysizesofHMScanbeeasilyandpreciselycontrolledbytheprefabricatedtemplates.3.ithasbeenwelldemonstratedthattheencapsulationoffunctionalnanoparticlesinhollowmaterialsnotonlyeffectivelyenhancesthestabilityofthesenanoparticles,butalsointroducenewfunctionalitiesforhollowmaterials.yolk/shellHMS,hasthusattractedtremendousinterestinrecentyears.However,thesynthesisandapplicationsofyolk/shellHMSarestillfacedwithchallenges.4.Inordertoobtainyolk/shellHMSwithmorecompositionaldiversity,severalothermethodshavethusbeenexploited,includingship-in-bottlemethods,partialetchingcoreofcore/shellcoresilica,multiplenanocasting,andsoft-templatingmethod.Howeverintrinsicdisadvantagesofthesemethods,suchaspoorcontrolofthegrowthoretchingofcore,time-consumingandcumbersomesyntheticprocedures,andlowefficiency.Toovercomethesedisadvantages.“self-template”.5.Inthisfeaturearticle,wefocusontherecentresearchprogressinthesynthesisandapplicationsofHMSbasedonself-templatingmethods.,2.Self-templatingstrategiesforsynthesisofHMS,Schematicillustrationsforsurface-protectedetchingstrategy(a)andstructuraldifference-basedselectiveetchingstrategy(b,c)forthesynthesisofHMSfromsSiO2.C18TMS:
n-octadecyltrimethoxysilane,TSD:
N-3-(trimethoxysilyl)-propylethylene-diamine.,Fig.1,2.1.Surface-protectedetching,TEMimagesshowingthemorphologyofPVPcoatedsSiO2afteretchingbyNaOHfor(a)0h;(b)1h;(c)2h45min;and(d)3h.Allscalebarsare200nm.,Fig.2,2.2.Structuraldifference-basedselectiveetching,TEMimages:
sSiO2C18/SiO2(a,b)andHMSobtainedbytreatingsSiO2C18/SiO2in0.6MNa2CO3solutionat80Cfor0.5h(c,d).,Fig.3,又如:
AuAPTES/SiO2SiO2,(a)TEMimageofsSiO2TSD/SiO2sSiO2,TEMimage(b)andSEMimages(c,d)ofyolk/shellSiO2HMSobtainedbyHFetchingofsSiO2TSD/SiO2sSiO2,(e)TEMimageofHMSobtainedbyHFetchingofTSD/SiO2sSiO2.,内层sSiO2,2.3.Cationicsurfactantassistedself-templating,highlydispersibleHMSparticlesaredesiredinsomeapplications,suchasbiomedicine.SincecationicsurfactantsinMCM-41-typeOMSarereadilyremovedbyamildextractionoperation,usingcationicsurfactantstodirecttheformationoforderedmesoporoussilicashellisexpectedtoprovideanopportunitytopreparehighlydispersibleHMS,InordertoobtainHMSwithorderedmesoporousshell,chosenquaternaryammoniumcationicsurfactantsasthestructure-directingagents,duetotheirfollowingproperties:
(1)theexcellentsolubility,
(2)highcriticalmicelletemperature(CMT),and(3)thestrongelectrostaticinteractionwithnegativelychargedsilicaspeciesinbasicconditions.(4)after-treatment,2.3.1.Cationicsurfactantassistedselectiveetching(strategy1),目标:
preparehighlydispersibleHMS、orderedmesoporoussilicashell.,TEMimagesofsilicaspheressSiO2-250(a)andHMSS-W-250(b),(c,d)N2sorptionisothermsandtheporesizedistributionofsSiO2-250and25HMSS-W-250.HMSS-W-250hasarathernarrowsizedistributioncenteredat2.5nm(Fig.6d),similartothatofMCM-41-typeOMSobtainedbyusingCTABasthestructure-directingagent,TEMimagesshowtheeffectofCTABconcentrationontheconversionofsSiO2toHMSS.TheCTABconcentrationusedwere(a)0mgmL-1,(b)0.1mgmL-1,(c)0.3mgmL-1,and(d)0.6mgmL-1,insets:
thecorrespondingTEMimagewithhighermagnification,(e)two45correlativereactionsintheCSASEstrategy,process:
(I)etching,and(II)co-assembly.,CTABplaystwoimportantrolesasfollows:
(1)thepromotertodrivethedissolutiondynamicsofthesSiO2andthereforeacceleratetheiretching;
(2)thesofttemplatetodirecttheformationofthewormhole-likemesoporesinhollowsilicashellbyco-assemblywiththeetched-outsilicaspecies.,2.3.1.Cationicsurfactantassistedselectiveetching,IntheCSASEstrategy,thebalancebetweenetchingprocessandredepositionprocessisalsoveryimportanttoformtheuniformmesoporousstructure.,2.3.1.Cationicsurfactantassistedselectiveetchingstrategy1,theas-obtainedHMSpresentsadisorderedporestructure(Fig8),20similartoHMSobtainedbyNaOHetchingofPVP-protectedsSiO2,Fig.8SEMandTEMimageoftheHMSobtainedbytheCSASEstrategyusingNaOHastheetchingagent.,2.3.2.Cationicsurfactantinducedselectiveetching(strategy2),(a)TEMimageofas-preparedsSiO2CTAB/SiO2(inset:
typicalTEMimageofasinglesSiO2CTAB/SiO2particle),(b)high-magnificationTEMimagecorrespondingtotheinsetof(a),(c)TEMimageofas-synthesizedHMSS-O(inset:
typicalTEMimageofsingle70HMSS-Oparticle),(d)high-magnificationTEMimagecorrespondingtotheinsetof(c).,2.3.3.NaAlO2andCTABco-assistedetching,(a)TEMimageofsSiO2,(b)photooftheas-synthesizedHMAS/CTABinadish,(c)SEMimageoftheassynthesizedHMAS(d),and(e)TEMimagesoftheas-synthesizedHMAS(inset:
high-magnificationimagecorrespondingtothedashedregion),(f)EDXspectrumoftheas-obtainedHMAS.,TEMimagesofthemorphologicalevolutioninthetime-dependentexperimentscarriedoutbyusing50mgofsSiO2:
(a)0.5h,(b)1h,(c)2h,and(d)3h.(e,f)TEMimagesoftheproductsobtainedbytheadditionofellipsoid-shapedhematitenanoparticles.Inset:
mappingofelementsbyEDXanalysisundertheSTEMmode.,3.ApplicationsofHMSmadebyself-templatingstrategies,Byadjustingstructure,sizeandcompositionoftheprefabricatedtemplates,theself-templatingstrategiesalloweasyfabricationofHMSandevenyolk/shellstructureswithcontrollablecomposition,sizeandporestructures.Consequently,theself-templatingstrategieshavebeenwellappliedinsynthesisofyolk/shellnanomaterialswithmesoporoussilicateshellforcatalysis,surface-enhancedRamanscattering,Andnanomedicine.Inthissection,summarizesomerepresentativeapplicationsofHMSmaterialsmadebytheself-templatingstrategies,withspecialfocusontheirapplicationsincatalysisandnanomedicine.,3.1.Synthesisofyolk/shellnanostructureswiththemesoporousshell,I:
surface-protectedetchingII:
structuraldifference-basedselectiveetchingIII:
cationicsurfactantassistedselectiveetchingIV:
cationicsurfactantinducedselectiveetching,V:
NaAlO2andCTABco-assistedetching.,3.2.Silica-basedyolk/shellnanostructuresasnanoreactors,UV_visspectrashowinggradualreductionof4-nitrophenolwithyolk/shellAuHMAS.(b)Plotofln(Ct/C0)versustimeforyolk/shellAuHMASandAusSiO2.Conversionof4-nitrophenolin10successivecyclesofreductionwithyolk/shellAuHMAS.TEMimageofthefinallyretrievedyolk/shellAuHMAS,3.3.Multifunctionalsilica-basedyolk/shellnanostructuresformultistepreactionsequences,Schematicillustrationofthemultistepreactionsequenceinvolvinganacidcatalysisandsubsequentcatalytichydrogenationforthesynthesisof2-(4-aminophenyl)-1H-benzimidazole.TEMimageofPd/AuHMAS.Synthesisyieldof2-(4-aminophenyl)-1H-benzimi-dazoleinthefivesuccessivereactionswithPd/AuHMAS.,Fig.13,3.4.Silica-basedhollow/yolk/shellnanostructuresindrugdelivery,(a)SchematicprocedureforthepreparationofHMSSNH2/DOXPdnanoparticles.(b)MassofPdnanosheetsinternalizedinHepG2cellsincubatedwithnakedPdnanosheetsandHMSS-NH2PdmeasuredbyICP-MS,(c)HepG2cellviabilitiesafter10hincubationwithdifferentconcentrationsoffreeDOX,HMSS-NH2PdandHMSS-NH2/DOXPdwithorwithout5minNIRirradiation(1W/cm2,808nm).,4.ConclusionandOutlook,1.Comparedwiththeconventionalsyntheticroutes,self-templatingmethodsshowmanyfascinatingadvantages,suchassimplesynthesisprocedures,lowproductioncost.Moreimportantly,self-templatingmethodsprovideastraightforwardroutetoyolk/shellmesoporoussilica.2.self-templatingmethodsareacileandeffectiveroutestosynthesizeholloworyolk/shellmesoporoussilicawithdesiredcomponent,size,morphology,andporestructures.3.self-templatingsynthesisandapplicationsofHMSstillpresentsbigopportunitiesandchallenges.4.midreactionconditions.5.Thecombineduseofreversemicellesandselectiveetchingstrategywillbringnewopportunitiesforthesynthesisofyolk/shellmesoporoussilicatewithdesiredcatalyticallyactivenoblemetalnanoparticles.6.catalysisandbiomedicineapplications,holloworyolk/shellmesoporoussilicamadebyself-templatingmethodsareexpectedtofindimportantapplicationsinmanyo
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