TailoringPolymericHydrogelsthroughCyclodextrinHost–GuestComplexationaXuhongGuo,*JieWang,LiLi,Duc-TrucPham,PhilipClements,StephenF.Lincoln,*BruceL.May,QingchuanChen,LiZheng,RobertK.Prud’hommeIntroductionThebasictenetthatinteractionsatthemolecularlevelcontrolcharacteristicsatthemacroscopiclevelisincreas-inglybeingexploitedinthedesignofnewmaterials.Thisismuchinevidenceinthedesignofbiocompatiblepolymerichydrogelsbymacromolecularassembly,whichhavepotentialapplicationsinbiodegradabledrug-deliverysystemsandchemicalsensors.[1]Recently,Wenz,RitterandHaradaemployedhost–guestcomplexationbetweencyclodextrinsandarangeofgueststocreatemacromole-cularnetworks.[2]Theoptimalsizematchbetweenb-cyclodextrin(b-CD)andadamantyl(AD)substituents[3]onsubstitutedpolymersresultsinhost–guestcomplexationthatformseffectivepolymercross-links,[2a]asdosimilarinteractionsbetweenb-CDandn-polyalkylsubstituentsinpolymersystems.[4]Inthisstudy,wehaveusedthisknowledgetotailorsubstitutedpoly(acrylate)s(PAAs)tocontrolhydrogelformationwiththeaimofpreparingbiomaterialsfortissueengineeringandcontrolleddrugdelivery.Aseriesofb-CDandAD3%randomlysubstitutedPAAs(Scheme1)inwhichshortamidetethers,a)PAAbCDandd)PAAAD;intermediatelengthdiacylamino-1,6-hexyl(hn)tethers,b)PAAbCDhnande)PAAADhn;and,longerdiacylamino-1,12-dodecyl(ddn)tethers,c)PAAbCDddnandf)PAAADddn,areusedinastudyofninepossiblesubstitutedPAAnetworks,exemplifiedbyg).Itisshownthatcompetitionbetweencomplexationbyb-CDsubstituentsofeitherADsubsti-tuentandthevariablelengthpolyalkanetethersattachingCommunicationX.Guo,J.Wang,L.Li,Q.Chen,L.ZhengStateKeyLaboratoryofChemicalEngineering,EastChinaUniversityofScienceandTechnology,Shanghai200237,PRChinaFax:þ862164253491.;E-mail:guoxuhong@ecust.edu.cnD.-T.Pham,P.Clements,S.F.Lincoln,B.L.MaySchoolofChemistryandPhysics,UniversityofAdelaide,Adelaide,SA5005,AustraliaE-mail:stephen.lincoln@adelaide.edu.auR.K.Prud’hommeDepartmentofChemicalEngineering,PrincetonUniversity,Princeton,NJ08544,USAa:Supportinginformationforthisarticleisavailableatthebottomofthearticle’sabstractpage,whichcanbeaccessedfromthejournal’shomepageathttp://www.mrc-journal.de,orfromtheauthor.Aclosecorrellationbetweenmolecular-levelinteractionsandmacroscopiccharacteristicsofpolymernetworksexists.Thecharacteristicsofthepolymerichydrogelsassembledfromb-cyclodextrin(b-CD)andadamantyl(AD)substitutedpoly(acrylate)scanbetailoredthroughselectivehost–guestcomplexationbetweenb-CDandADsubstituentsandtheirtethers.Dominantly,stericeffectsandcompetitiveintra-andintermolecularhost–guestcomplexationarefoundtocontrolpoly(acrylate)isomericinter-strandlinkageinpolymernetworkformation.Thisunderstandingofthefactorsinvolvedinpolymerichydrogelformationpointsthewaytowardstheconstructionofincreasinglysophis-ticatedbiocompatiblematerials.300Macromol.RapidCommun.2010,31,300–304�2010WILEY-VCHVerlagGmbH&Co.KGaA,WeinheimDOI:10.1002/marc.200900560eithersubstituenttothePAAbackbonestogetherwithstericinteractionswiththePAAbackbonescontroltheconstructionofthehydrogels.The1Dand2D1HNOESYNMRspectraofthesubstitutedPAAs,a–f),inD2Oareunexceptionalexceptforthoseofb)PAAbCDhnandc)PAAbCDddn.Theseshowweakandstrongcross-peaks,respectively,arisingfrominteractionsbetweentheb-CDsubstituentH3,5,6annularprotonsandthoseofthehnandddntethersconsistentwiththeirintramolecularhost-guestcomplexationbytheb-CDsubs...
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