ChiYao2012.11.16Nanotechnology,DiscoveringaTinyWorld.Contents1.Introduction2.PuttingNanotechnologyto

use3.Nanotechnologyinourresearchfield4.ConclusionWhatisnanotechnology?“Theunderstandingandcontrolofmatteratdimensionsofroughly1to100nanometers(nm),whereuniquephenomenaenablenovelapplications.”

Developmentsduringthepastdecadeinbiochemistry,physicalchemistry,microscopy,andengineeringhaveresultedinatremendousupsurgeofinterestinthepropertiesofverysmallparticlesandtheirpossibleapplicationsinawidevarietyofproducts.Technologicalinnovationshaveenabledthemanipulationoftinystructurescalleddendrimers,quantumdots,nanoshells,nanotubes,andbuckyballs(fullerenes),etc.——NationalScienceFoundation1.Introduction2.PuttingNanotechnologytouseOverthepasttwodecades,scientistsandengineershavebeenmasteringtheintricaciesofworkingwithnanoscalematerials.Nowresearchershaveaclearerpictureofhowtocreatenanoscalematerialswithpropertiesneverenvisionedbefore.Productsusingnanoscalematerialsandprocessarenowavailable.2.1Drug-DeliveryTechniqueDendrimersareatypeofnanostructurethatcanbepreciselydesignedandmanufacturedforawidevarietyofapplications,includingthetreatmentofcancerandotherdiseases.Dendrimerscarryingdifferentmaterialsantheirbranchescandoseveralthingsatonetime,suchasrecognisingdiseasedcells,diagnosingdiseasedstates(includingcelldeath),drugdelivery,reportinglocation,andreportingoutcomesoftherapy.2.2NanofilmsDifferentnanoscalematerialscanbeusedinthinfilmstomakethemwaterrepellent,antireflective,self-cleaning,Ultravioletorinfrared-resistant,anti-fog,anti-microbial,Scratchresistant,orelectricallyconductive.Nanofilmsareusednowoneyeglasses,computerdisplayandcamerastoprotectortreatthesurfaces.2.3WaterFiltrationtechniqueResearchersareexperimentingwithcarbonnanotubesbasedmembranesforwaterdesalinationandnanoscalesensorstoidentifycontaminantsinwatersystem.Othernanoscalematerialsthathavegreatpotentialtofilterandpurifywaterincludenanoscaletitaniumdioxide,whichisusedinsunscreenandwhichhasbeenshowntoneutralizebacteria.T.Trungetal.,MaterialsLetters,

57(2003),2746–27502.4NanoTubesCarbonnanotubes(CNTs)areallotropesofcarbonwithacylindricalnanostructure.Nanotubeshavebeenconstructedwithlength-to-diameterratioofupto28,000,000:1,whichissignificantlylargerthananyothermaterial.Thesecylindricalcarbonmoleculeshavenovelpropertiesthatmakethempotentiallyusefulinmanyapplicationsinnanotechnology,electronics,opticsandotherfieldsofmaterialsscience,aswellaspotentialusesinarchitecturalfields.TheyexhibitextraordinarystrengthanduniqueElectricalproperties,andareefficientconductorsofheat.2.5NanoscaleTransistorsTransistorsareelectronicswitchingdeviceswhereasmallamountofelectricityisusedlikeagatetocontroltheflowoflargeramountofelectricity.Incomputers,themoretransistors,thegreaterthepower.Transistorssizeshavebeendecreasing,socomputerhavebecomemorepowerful.Untilrecently,theindustry’sbestcommercialtechnologyproducedcomputerchipswithtransistorshaving45-nanometerfeatures.3.Nanotechnologyinourresearchfield

3.1.UpconvertingNanoparticlesPhotoUpconversionPhotoexcitationatacertainwavelengthintheNIRfollowedbyluminescenceatashorterwavelengthintheVISiscalledNIRtoVISphotonupconversion.

Aratherunusualprocesssincelowenergyphotonsare"converted"tohigherenergyphotons.AtleasttwoNIRphotonsarerequiredtogenerateoneVISphoton.

YbTmErNaYF4orNaGdF4:Yb,Er,TmMulticolorupconversionemission980nmCWlaserexcitationenergyleveldiagramUpconversionluminescenceprimarilyoriginatesfromelectrontransitionsbetweenenergylevelsoflocalizeddopantions.MulticolorupconversionemissionX.G.Liuetal.Analyst,

135,1839,2010X.G.Liuetal.Analyst,

135,1839,2010Summaryofbiologicalapplicationsoflanthanide-dopedupconversionmaterialsBiologicalapplicationsBiologicalapplicationsInvitrodetectionChem.Soc.Rev.,2009,38,976InvivoimagingBiologicalapplicationsChem.Soc.Rev.,2009,38,976FRET-basedsensingBiologicalapplicationsChem.Soc.Rev.,2009,38,976Today,manyofournation’smostcreativescientistsandengineersarefindingnewwaystousenanotechnologytoimprovetheworldinwhichwelive.Althoughtherearemanyresearchchallengesahead