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1、ARTICLEINPRESSBiomaterials24(2003)3671–3679Surfacemodificationofhydroxyapatite.PartI.DodecylalcoholL.Borum-Nicholas,O.C.WilsonJr.*Biomimetics,Orthopedics,andNanomaterialsExploration(BONE)Lab,DepartmentofMaterialsandNuclearEngineering,UniversityofMarylan
2、d,Building046,rm2200,CollegePark,MD20742,USAReceived24July2002;accepted30March2003AbstractTheinfluenceofesterificationreactionsonthesurfacechemistryandcolloidstabilityofhydroxyapatite(HAP)wasstudiedbyagingnanophaseHAPindodecylalcoholatelevatedtemperature
3、s(115Cand190C).TheesterifiedHAPparticleswerecharacterizedbyX-raydiffraction,transmissionelectronmicroscopy,diffusereflectanceinfra-redFouriertransformspectroscopy(DRIFTS),thermalgravimetricanalysis,sedimentationtimestudies,andelectrophoreticmobility(m)
4、measurementsinwaterandethylalcohol.DRIFTSanalysisrevealedthattheHAPsurfacewasmodifiedbydodecylgroupsbasedontheappearanceofC–H1stretchvibrationalmodesat2962,2930,and2860cm.DodecylalcoholmodifiedHAPexhibitedalargerTGAmasslossuponheating(upto4.8%)comparedt
5、ountreatedHAP(2.5–3.2wt%).Sedimentationstudiesrevealedthefollowingstabilitytrends:HAPdispersedinwaterwasapproximatelythesameasesterifiedHAPinwater(afewhours)oHAPinethylalcohol(1–7days)5esterifiedHAPinethylalcohol(115C,70h;190C,over65days).Thedifference
6、sincolloidstabilityareattributedtoLewisacid/baseinteractionsfortheuntreatedHAPandstericstabilizationeffectsforthenanophaseHAPwithsurfacedodecylgroups.r2003ElsevierScienceLtd.Allrightsreserved.Keywords:Hydroxyapatite;Surfacemodification;Dodecylalcohol;Su
7、rfaceesterification;Colloidstability1.Introductiontemporaryandparticleagglomerationensuesoncethemixingenergyisremoved.Whilehydroxyapatite(HAP)isthemostthermody-ChemicaltechniquescanprovideamorepermanentnamicallystablecalciumphosphatephaseatthepH,solutio
8、ntotheproblemofHAPcolloidstability.Thetemperatureandcompositionofphysiologicalfluids[1],HAPsurfacemaybealteredviaadsorptionofionsoritscolloidstabilitypresentsanumberofproblemsinthemolecules,dissolution/reprecipitation,encapsulation,or2+3
