incorporated electrospun polycaprolactone in nanoﬁbers system Drug delivery based on cyclodextrin-naproxen inclusioncomplex Colloids and Surfaces B: Biointerfaces

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ContentslistsavailableatScienceDirect

Colloids and Surfaces B: Biointerfaces

jou rn a l h om ep ag e :w w w . e l s e v i e r . c o m / l o c a t e / c o l s u r f b

Drug delivery system based on cyclodextrin-naproxen inclusion complex incorporated in electrospun polycaprolactone nanoﬁbers

M. Fatih Canbolat

^a,c,∗∗

, Asli Celebioglu

^a,b

, Tamer Uyar

^a,b,∗

aUNAM-NationalNanotechnologyResearchCenter,BilkentUniversity,Ankara06800,Turkey

bInstituteofMaterialsScience&Nanotechnology,BilkentUniversity,Ankara06800,Turkey

cSuleymanDemirelUniversity,EngineeringFaculty,TextileEngineering,Isparta32260,Turkey

a r t i c l e i n f o

Articlehistory:

Received4July2013

Receivedinrevisedform9November2013 Accepted11November2013

Availableonline19November2013

Keywords:

Nanoﬁbers Drug Cyclodextrin Inclusioncomplex Naproxen Release

a b s t r a c t

Inthisstudy,we selectnaproxen(NAP) asareferencedrugand electrospunpoly(␧-caprolactone) (PCL)nanofibersasafibrousmatrix forourdrug-deliverysystem.NAPwas complexedwithbeta- cyclodextrin(␤CD)toforminclusioncomplex(NAP-␤CD-IC)andthenNAP-␤CD-ICwasincorporated intoPCLnanofibersviaelectrospinning.TheincorporationofNAPwithoutCD-ICintoelectrospunPCL wasalsocarriedoutforacomparativestudy.OuraimistoanalyzethereleaseprofilesofNAPfrom PCL/NAPandPCL/NAP-␤CD-ICnanofibersandweinvestigatetheeffectofCD-IConthereleasebehav- iorofNAPfromthenanofibrousPCLmatrix.ThecharacterizationofNAP-␤CD-ICandthepresenceof CD-ICinPCL/NAP-␤CD-ICnanofiberswerestudiedbyFTIR,XRD,TGA,NMRandSEM.TheSEMimaging oftheelectrospunPCL/NAPandPCL/NAP-␤CD-ICnanofibersrevealthattheaveragefiberdiameterof thesenanofibersisaround300nm,inaddition,theaggregatesofCD-ICinPCL/NAP-␤CD-ICnanofibersis observed.ThereleasestudyofNAPinbuffersolutionelucidatethatthePCL/NAP-␤CD-ICnanofibershave higherreleaseamountofNAPthanthePCL/NAPnanofibersduetothesolubilityenhancementofNAPby CD-IC.

1. Introduction

Themainfunctionofdrugdeliverysystemsistotransportvari- ousdrugstothetargetsitesinthebodyinasecurewayandadjust thereleasemechanismsbycontrollingtheamountofdrugsand treatmenttime[1,2].Thereareseveralcarriersandformulations usedfordrugdeliverypurposessuchaspolymericmatrices,gels, cyclodextrins,liposomes,microspheres,foams,ﬁlmsandsomeoth- ers[3–8].Indrugdelivery,itisexpectedfromacarriermaterialto haveatleastfollowingproperties;biocompatibility,non-toxicity, lackof immunogenicity, acceptablebiodegradationtime, repro- ducibility,andcontinuousactivationtillarrivaltothetarget[9,10].

Nanostructures and cyclodextrins (CD) present signiﬁcant opportunities in drug delivery systems with their unique and promising characteristic features. Nanostructures improve the releasebehaviorandstabilityofthedrugsbymaintainingthedrug

∗ Correspondingauthorat:UNAM-NationalNanotechnologyResearchCenter, BilkentUniversity,Ankara06800,Turkey.Tel.:+903122903571;

fax:+903122664365.

∗∗ Correspondingauthorat:SuleymanDemirelUniversity,EngineeringFaculty, TextileEngineering,Isparta32260,Turkey.Tel.:+902462111188;

fax:+902462111180.

E-mailaddresses:fatihcanbolat@sdu.edu.tr(M.F.Canbolat), tamer@unam.bilkent.edu.tr(T.Uyar).

concentrationwithinatherapeuticwindowandovercomingthe biologicalbarriersforcellularuptake[11,12].Ontheotherhand, CDsinduceimprovementindrugreleaseproﬁlesandenhancement indrugsolubilizationandstabilizationbyforminginclusioncom- plexes(ICs)withdrugs[13,14].However,thereisnostandardor idealstructureavailablefordrugdeliverypurposeandmanystud- iesarereportedondevelopingmuchbetterstructuresforthesite speciﬁcdrugtargeting[15–17].

Naproxen(NAP)isapoorlywatersoluble,non-steroidalanti- inflammatory drug (NSAIDs) that is used to relieve pain or inflammation [18,19]. Yet, enhanced solubilityachievements of naproxen by formingcyclodextrin inclusion complexes (CD-IC) were reported [20,21]. Apart from CD, the use of electrospun nanofibersasanincorporatingmatrixalsoenhancedtherelease behaviorofNAPincomparisonwithcastfilms[22].However,the main functionofelectrospunnanofibersin drugdeliveryappli- cationscanbedefinedastheircontrolledandsustainedrelease behaviors[23,24].Indrugdeliveryfield,whilethere arestudies aboutincorporationofCDsintopolymericstructuressuchashydro- gelsandfilms[25,26],averylimitednumberofreportsareavailable relatedtoincorporationofCD-ICofactiveagents suchasdrugs [27],antibacterials[28],essentialoils[29]andflavors/fragrances [30–33]intoelectrospunnanofibersfordeliveryandstabilization purposes.Forinstance,usingcyclodextrinasastabilizingandsolu- bilizingagentandelectrospunnanofibermatsasacarriermatrix 0927-7765/$–seefrontmatter©2013ElsevierB.V.Allrightsreserved.

http://dx.doi.org/10.1016/j.colsurfb.2013.11.021

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16 M.F.Canbolatetal./ColloidsandSurfacesB:Biointerfaces115(2014)15–21

forsustainedreleasemayopenupnewpathwaysfordrugdelivery purposebasedonimprovedreleaseperformanceofthedrug.

CDs(␣-,␤-,and ␥-types)are cyclic oligosaccharides which areenzymaticallyconvergedfromstarchthatcompriseglucopy- ranosideunitslinkedwith␣(1–4)bonds[34].CDsarehollowand truncatedconeshapedmoleculesthathavehydrophobiccavityand hydrophilicoutershellwhichenablethemtoconstitutenoncova- lenthost–guestinclusioncomplexationwithvarietyofmolecules invariousforms[34,35].Ontheotherhand,electrospunnanofibers areotherpromisingnanostructuresindrugdeliveryapplications [36–38].Therearemanyreasonsfornanofiberstructurestobepre- ferredandusedinbiomedicalapplicationareas,i.e.,smallfibersize, highporosity,interconnectedporousstructure,andcapabilityto embedvariousfunctionaladditivesintothem.

In this study, naproxen (NAP) and inclusion complex of naproxenwithbeta-cyclodextrin(NAP-␤CD-IC)wasincorporated intopolycaprolactone(PCL)electrospunnanofibersforourdrug- deliverysystem.Wecompared therelease profilesofNAPfrom PCL/NAPand PCL/NAP-␤CD-ICnanofibersandwe examinedthe effectofinclusion complexationonthereleasebehavior ofNAP fromthenanofibrousPCLmatrix.Inthisregard,wefirsttestedthe effectof␤CDonthesolubilityofNAPbyforminginclusioncomplex- ation.NAPshowshighersolubilityinNAP-␤CD-ICwhencompared tofreeNAPwhichisconsistentwiththeliterature[39,40].Parallel tothisresult,improvedreleaseprofileofNAPfromPCL/NAP-␤CD- ICnanofibersisobserved,aswell.

2. Experimental 2.1. Materials

Naproxen (NAP) was commercially purchased from Abdi Ibrahim Pharmaceutical Company (Turkey). Polycaprolactone (PCL)(Mw:80,000,SigmaAldrich),N,N-dimethylformamide(DMF) (Riedel,Pestanal),dicholoromethane (DCM)(Sigma,ExtraPure), and potassium dihydrogen phosphate (VWR, Chromanorm for HPLC)wereobtainedcommerciallyfromvarioussuppliers.Beta- cyclodextrin (␤CD) was obtained from Wacker Chemie AG (Germany)andthede-ionizedwaterwasobtainedfromtheMil- liporeMilli-QUltrapure WaterSystem.Allmaterialswereused withoutanypuriﬁcation.

2.2. ThepreparationofsolidˇCD-NAPinclusioncomplex (NAP-ˇCD-IC)

FortheNAP-␤CD-ICformation,1gof␤CDwasdissolvedin18ml waterand250mgNAPwasdispersedin2ml water,separately.

Then,theNAPsolutionwasaddedintoCDsolutionslowly.Ulti- matesolutionwasstirredover-nightandaturbiddispersionwas obtained.Itwaskeptat−80^◦Candfreeze-dried toobtainNAP-

␤CD-ICpowder.

2.3. Thepreparationofelectrospinningsolutions

TheNAP-␤CD-ICincludingPCLsolutionwasobtainedbydis- persingtheNAP-␤CD-ICpowderinclearandhomogenousPCL(15%

(w/v),withrespecttosolvent)DMF/DCM(3:1,v/v)solution,atthe 20%(w/w)polymerconcentration.Forcomparison,thepurePCL (15%,w/v)andonlyNAPincluding(4%(w/w)withrespecttopoly- merconcentration)PCL(15%,w/v)solutionswerealsopreparedin DMF/DCM(3/1,v/v)blendsystem.

2.4. Electrospinning

ThePCL,PCL/NAPandPCL/NAP-␤CD-ICsolutionswereplaced ina 3mlsyringe ﬁttedwitha metallic needle of 0.6mm inner

diameter. The syringe was ﬁxed horizontally on the syringe pump (model SP 101IZ, WPI, USA). The positive electrode of thehigh-voltagepowersupply (MatsusadaPrecision,AUSeries, Japan)wasclampedtothemetalneedle tip,and thecylindrical aluminum collectorwasgrounded.The parameters oftheelec- trospinningwereadjustedas;feedrateofsolutions=1ml/h,the appliedvoltage=15kV,andthetip-to-collector distance=10cm.

Electrospunnanoﬁbersweredepositedonagroundedstationary cylindricalmetalcollectorcoveredwithapieceofaluminumfoil.

TheelectrospinningapparatuswasenclosedinaPlexiglasbox,and electrospinningwascarried outat25^◦C,20% relativehumidity.

Thecollectednanoﬁbersweredriedatroomtemperatureunder thefumehoodovernight.

2.5. Measurementsandcharacterization

TheexactmolarratiobetweenNAP:␤CDintheinclusioncom- plexwasdeterminedbyusingprotonnuclearmagneticresonance (¹HNMR,BrukerDPX-400)system.TheNAP-␤CD-ICpowderwas dissolvedind6-DMSO(in20g/Lconcentration).Thespectrawere recordedat 400MHz and at16 total scan. A rheometer(Anton PaarPhysicaCR301)equippedwithacone/plateaccessory(spin- dletypeCP40-2)wasusedtomeasuretherheologicalbehaviorof PCL,PCL/NAPandPCL/NAP-␤CD-ICsolutionintherangeof0.1to 1001/sshearrate.Thescanningelectronmicroscope(SEM)(FEI Quanta200FEG)wasusedforthemorphologicalanalysisofthe electrospunnanofibers.Samplesweresputteredwith5nmAu/Pd priortoSEMimaging.Theaveragefiberdiameter(AFD)wasdeter- minedfromtheSEMimages,andaround100fiberswereanalyzed.

The crystallinestructure determination of the NAP, ␤CD, NAP-

␤CD-ICpowderandPCL,PCL/NAPandPCL/NAP-␤CD-ICnanofibers wereinvestigated byusingX-raydiffraction(XRD) (PANalytical X’Pertpowderdiffractometer)havingCuK␣radiationinarangeof 2=5–30^◦.Thethermalpropertiesofelectrospunnanofiberswere studiedbythermogravimetricanalysis(TGA)(TAQ500)andthe measurementswerecarriedout from25to500^◦C at20^◦C/min heatingrate,andN2wasusedasapurgegas.Theinfraredspectraof thenanofiberswereobtainedbyusingaFouriertransforminfrared spectrometer(FTIR)(Bruker-VERTEX70).For measurement,the samplesweremixedwithpotassiumbromide(KBr)andpressed aspellets.Thescans(64scans)wererecordedbetween4000cm⁻¹ and400cm⁻¹ataresolutionof4cm⁻¹.UV–vis-spectroscopy(Var- ianCary5000) wasused todeterminethesolubility difference betweenpureNAPandNAP-␤CD-IC.Forthispurpose,5×10⁻⁴M NAPpowderandNAP-␤CD-ICthatincludesthesameamountof NAPweredissolvedinwater.After24hstirring,thesolutionswere filteredandtheUVabsorbanceofsampleswasmeasuredinthe 250–370nmrange.

2.6. TheNAPreleaseproﬁlefromelectrospunPCLnanoﬁbers

TheHPLCsystem(Agilent1200Series)wasusedtoinvestigate thereleaseproﬁlesofPCL/NAP andPCL/NAP-␤CD-ICnanoﬁbers.

TheseparationofNAPwasperformedwithZorbaxEclipseXDB-C18 column(150mm×4.6mm,5␮mparticlesize)anditwasdetected at 230nm wavelength. Acetonitrile (100%) was used asmobile phaseataflowrateof1ml/minandtheinjectionvolumewaskept at10␮l.Forthetest,30mgweightedPCL/NAPandPCL/NAP-␤CD- ICnanofiberswereimmersedinto30mlbuffersolutionsandthey werekeptinthatbuffertodeterminethereleasedamountofNAP attheprogressingtimeintervals.Theexperimentswererepeated threetimesforbothcompositenanofibers.Thecalibrationcurve of NAP was prepared by using stock solutions in 7 different concentrations;20ppm, 10ppm, 5ppm, 2ppm, 1ppm, 0.5ppm and0.2ppm.ItshowedlinearityandacceptabilitywithR²≥0.99.

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Fig.1.¹HNMRspectrumofNAP-␤CD-ICdissolvedind6-DMSO.

Themeasurementresultswereadaptedtothiscalibrationcurve intermsofpeakareaundercurves.

3. Resultsanddiscussion

Naproxen(NAP)waschosenasareferencedruginthisstudy based on its well-known inclusion complex formation ability withbeta-cyclodextrin(␤CD)[19,41,42].Thereleasebehaviorof NAPafterdirectincorporationintoPCLnanofibers(PCL/NAP)and afterNAP-␤CD-ICformationandincorporationintoPCLnanofibers (PCL/NAP-␤CD-IC)wereexaminedinthepresentstudy.Themain objectiveofthisstudyistogetbetterreleaseprofileofNAPfrom PCL/NAP-␤CD-ICnanofibersduetohighersolubilityenhancement ofNAPby␤CD-ICformation.

In the first step, NAP-␤CD-IC was formed by freeze-drying method.Themixingratiosof1:4(w/w)waschosenforNAP-␤CD to provide molar ratio as 1:1.2 for the proper inclusion complex formation. In further steps, several characterization tests were performed to prove theinclusion complex formation. To testthesolubilityofNAP by␤CD-ICformation,UV–visanalysis wasperformed.Then,releaseprofilesofNAPfromPCL/NAPand PCL/NAP-␤CD-ICnanofibrousmatsinbuffersolutionswereana- lyzedbyHPLCmethod.

3.1. Inclusioncomplexcharacterization

1HNMRstudywasperformedtoﬁgureoutthemolarratioof NAP-␤CDandamountofNAPintheinclusioncomplex.Fig.1indi- catesthe¹HNMRspectrumoftheNAP-␤CD-ICpowder.Themolar ratiowascalculatedbytakingtheintegralofNAPpeakatabout 1.4ppm[43]and␤CD’scharacteristicpeakatabout4.8ppm[44]in d6-DMSOsystem.Itwasfoundthat,NAP-␤CD-IChave1:1.2molar ratiowhentheintegralsofmentionedpeakswereproportionedto eachotherandthisratioisquitewellagreewithourinitialmixing ratio.

Then,weusedFTIRspectroscopytoobservethespectralchanges and therepresentative bands of thespectrafor the substances beforeandafterICformation.TheFTIRspectraofpureNAP,pure

␤CDandNAP-␤CD-ICaredepictedinFig.2a.IntheFTIRspectrum ofNAP,distinctabsorptionbandat1029cm⁻¹correspondstoC O stretching,at1228cm⁻¹ correspondsto O stretching,and at 1395cm⁻¹ correspondstoCH3 bending.Peaksat1685cm⁻¹ and

1729cm⁻¹correspondtoanti-symmetricalandsymmetricalC O stretchingvibrations[45,46].Incaseof␤CDspectra,characteristic peaksareappearedat1029cm⁻¹,at1080cm⁻¹and1157cm⁻¹due toC Ostretch,at1638cm⁻¹duetoH OHbending,at2927cm⁻¹ duetoC Haliphaticstretch,andat3401cm⁻¹duetoO Hstretch- ing[45–47].TheFTIRspectrumofNAP-␤CD-ICshowsabandat about1730cm⁻¹whichcomesfromNAPwithaslightshiftwhich isinanagreementwiththeliterature[41,42,46].Alsoitwasseen thattypicalpeaksoftheNAPweresuppressedintheNAP-␤CD-IC spectrawhichsuggestedthesuccessfulICformation.

Fig.2. FTIRspectraof(a)NAP,␤-CDandNAP-␤CD-IC,and(b)PCL,PCL/NAPand PCL/NAP-␤CD-ICnanoﬁbers.

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Fig.3.XRDdiffractionpatternsof(a)NAP,␤-CDandNAP-␤CD-IC,and(b)PCL, PCL/NAPandPCL/NAP-␤CD-ICnanoﬁbers.

TheXRDpatternsofthepureNAP,pure␤CDandNAP-␤CD- IC were recorded toinvestigate thepossible differences in the crystallinityofthestructures.AsitcanbeseenfromFig.3a,for theNAP-␤CD-IC,distinctdiffractionpeaksforthecrystallineNAP weredetectedintheXRDpatternsindicatingthatsomefreeNAP presentintheNAP-␤CD-ICpowder.Alsothecharacteristicpeaks ofchannel-typepackingstructureat2∼12^◦,18^◦,and19^◦of␤CD wereobservedfortheNAP-␤CD-ICwhichshowsthesuccessfulIC formationofNAPwith␤CD[48].

TGAthermogramsofpureNAP,pure␤CDandNAP-␤CD-ICare shown inFig. 4a. TGAthermogramsshow weightlosses below 100^◦Cforboth␤CDandNAP-␤CD-ICduetowaterlossandmain degradation wasobserved for NAP at 268^◦C and at 350^◦C for

␤CD.Thewaterlosswasabout11%for␤CDwhileitwasaround 8%for NAP-␤CD-IC.The 3%difference mightbe attributableto theexistenceofNAP insteadofwater inthe␤CD cavity.Other thantheinitialweightloss,therearetwoweightlossesseenfor NAP-␤CD-IC.Firstoneisbetween150^◦C and250^◦Candsecond oneisbetween300^◦Cand350^◦CwhichcorrespondstofreeNAP and IC weight losses that merged with theCD decomposition, respectively.Therelativelessdecomposedamountofuncomplexed free NAP than the initial amount and the higher temperature shift in the NAP–␤CD part prove the successful formation of NAP-␤CD-IC.

TheUV–visspectroscopymeasurementsofNAPandNAP-␤CD- ICsolutionsweredisplayedinFig.5.Asitcanbeseenfromthe spectra,theabsorptionintensityofNAP-␤CD-ICsolutionishigher thanNAP powder for thesameamount ofNAP (5×10⁻⁴M).It ismainlybecause,theinclusioncomplexationofNAPwith␤CD enhancethesolubilityofinsolubledrug,NAP,in watermedium andleadstohigherintensityoccurrenceinUV–vis-spectra.Thus, theinclusioncomplexationandthesolubilityenhancementarealso provedbytheUV–vismeasurements.

Fig.4.TGAthermogramsof(a)NAP,␤-CDandNAP-␤CD-IC,and(b)PCL,PCL/NAP andPCL/NAP-␤CD-ICnanoﬁbers.

3.2. Characterizationofelectrospunnanoﬁbers

Following the characterization studies of NAP-␤CD-IC, PCL polymer matrix was chosen for the production of electrospun nanofibers.SincePCLiswaterinsolubleandbiodegradablepoly- mer[49,50],itisthoughtthattheuseofPCLnanofibersasadrug deliverysystemmightexhibitconvenientreleaseprofileforNAP.

FollowingconcentrationadjustmentsofthePCL/NAPandPCL/NAP-

␤CD-ICblends,electrospinningandcharacterizationstudieswere performed.

Weinvestigatedthemorphologyofelectrospunnanofibersof purePCL,PCL/NAPandPCL/NAP-␤CD-ICbySEMimaging.Therep- resentativeimagesofSEMmicrographsweregiveninFig.6and fiberdiameterdistributiondataweresummarizedinTable1.Uni- form,beadfreenanofiberswithdiametervariationwereobtained fromallthreePCLbasednanofibroussamples.Itis clearlyseen intheFig.6cthatthereareICcrystalaggregatesaccumulatedin

Fig.5.SolubilityanalysisofNAPbyUV–visspectroscopy;solubilityofpureNAPand solubilityofNAPfromNAP-␤CD-IC.

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Table1

Polymersolutionparametersandaveragefiberdiametervaluesofelectrospunnanofibers(thefibersizeisreportedastheaverage±standarddeviation;foreachcase100 fiberswereanalyzed).

Solvents Concentrations Viscosity(Pas) Averageﬁberdiameter(nm)

PCL DMF/DCM(3:1,v/v) 15%(w/v) 0.465 336±100

PCL/NAP DMF/DCM(3:1,v/v) 15%(w/v)/4%(w/w) 0.675 361±152

PCL/NAP-␤CD-IC DMF/DCM(3:1,v/v) 15%(w/v)/20%(w/w) 0.745 389±167

theﬁbermatrixwhichprovesthesuccessfulincorporationofNAP-

␤CD-ICintoelectrospunPCLnanofibers.Itwasfoundoutthatfiber diameterdistributions have good correlationwiththeviscosity measurementresultsascanbeseeninTable1.Theincorporation ofNAPandNAP-␤CD-ICintoPCLmatrixcausedviscosityincrease inthepolymersolutionswhichfinallytriggeredtheformationof nanofiberswithlargerdiameters.

WeperformedFTIRstudiesfornanofibersofpurePCL,PCL/NAP andPCL/NAP-␤CD-ICsamples(Fig.2b).TypicalpeaksforthePCLare observedat2949cm⁻¹and2865cm⁻¹duetoCH₂stretchingvibrations,at1731cm⁻¹duetoC Ostretchingvibrations,at1471cm⁻¹, 1397cm⁻¹,and 1365cm⁻¹ due toCH2 bendingvibrations.Also C OandC Cstretchingvibrationsat1293cm⁻¹,C O Cstretch- ingvibrationsat1240cm⁻¹,1169cm⁻¹,1108cm⁻¹,and1048cm⁻¹ wedetected[51–53].InFTIRspectraofPCL/NAPnanofibers,the characteristicpeaksofPCLmostlyexistwhilenoneofthecharacter- isticpeaksofNAPwasobservedwhichismostprobablyduetothe dominanteffectofthePCLpeaksandtherelativelylowconcentra- tionofNAPinthepolymermatrix(∼4%,w/w).Forinstance,almost allthepeaksinthefingerprintregionarequitewellfittedwith PCLcharacteristicpeaks.However,thereisagoodindicationabout theexistenceofNAPduetosomeshiftedpeaksat2869cm⁻¹and 2952cm⁻¹whiletheyarelocatedat2865cm⁻¹and2949cm⁻¹in thePCLspectra.TheFTIRspectrumofPCL/NAP-␤CD-ICnanofibers hasverysimilarcharacteristicfeatureswithPCL/NAPnanofibers.

Again,PCLpeakswereoversaturatedinthespectrawhile␤CD-IC peaksweresuppressed,evenoneofthemostdistinctpeakof␤CD at1029cm⁻¹isnotvisible.AlthoughtheFTIRspectradidnotdepict

Fig.6. SEMmicrographsof(a)PCL,(b)PCL/NAPand(c)PCL/NAP-␤CD-ICnanoﬁbers.

anyinteractionbetweenPCLand NAP-␤CD-ICin terms ofpeak shifts,wecannotrule-outsuchcase.Itisduetothefactthatthe signalfromtheFTIRspectraoriginatesfromtwospecies,namely, interactionandnon-interactionofPCLwithNAP-␤CD-IC.Alsowe haveonly4%ofNAPinPCLandhencethesignalispredominantly comingfromPCL.

X-raydiffractionpatternsofpurePCL,PCL/NAPandPCL/NAP-

␤CD-ICnanoﬁbrousmatsaregiveninFig.3b.NAPandNAP-␤CD-IC arecrystallinematerials,however,theXRDpatternsofPCL/NAP andPCL/NAP-␤CD-ICnanoﬁbrousmatsrevealedthat bothNAP-

␤CD-ICandNAPtransformedintoamorphousphasefollowingthe incorporationintothePCLnanoﬁbrousmatrix.

In TGA thermograms,main degradation of NAP in PCL/NAP nanoﬁberswasfoundoutbetween200–250^◦CwhileforPCL/NAP-

␤CD-ICnanofibers, it wasfound outbetween 300–375^◦C from theTGAanalysis.TheTGAthermograminFig.4brevealsthatPCL nanofibersshowmaindegradationatabout420^◦C.BylookingTGA thermograms,itispossibletoclaimtheexistenceofNAPmolecules andNAP-␤CD-ICinthePCL/NAP-␤CD-ICnanofibers.Inbothcases, forPCL/NAP andPCL/NAP-␤CD-ICnanofibers,two weightlosses wereseenafter100^◦Cwhichareindependentfromwaterlosses.

We studied the release profiles of NAP from PCL/NAP and PCL/NAP-␤CD-ICnanofibersinbuffersolutionforabout20htime period by HPLC. The amount of PCL/NAP and PCL/NAP-␤CD-IC nanofibersusedforthereleasestudywasadjustedaccordinglyin ordertohavethesameamountofNAPinthesesamples.Forboth samples,afterslightburstingofthedrug,slowreleasebehavior wasobservedfor12hperiod.Then,NAPshowedsustainedrelease profilesduetothebalancedconditionssuchashavingsamediffu- sionresistancefordifferenttimeintervals[54].Thereleaseprofiles revealedthatPCL/NAP-␤CD-ICnanofibroussystemhasmorethan twotimeshigherreleaseratethanPCL/NAPnanofibroussystem whichisverypromisingresultforthedrugdeliverypurpose(Fig.7).

ItalsorevealedthattheformationofNAP-␤CD-IChelpedNAPto releasefromnanofibrousmatmucheasierwhichisquitevitalin drugdeliveryapplications.Asitwasprovenbyoursolubilitytest, CD-ICformationhelpsNAPtodissolveinwatermuchbetterwhich showsitseffectonthereleasebehaviorofNAPafterincorporated intonanofibrousmat.Theeasyandhigherreleaseofdrugisimpor- tantfor somespecifictargetsindrugdelivery.It iswell-known

Fig.7.ReleaseproﬁleofNAPfromPCL/NAPandPCL/NAP-␤CD-ICnanoﬁbrousmats byHPLCwithstandarddeviations(eachanalysisrepeated3times,n=3).

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phenomenathatnanofiberscanenhancethereleasebehaviorof drugswiththeirhighsurfaceareatovolumeratio[55,56].Inthis study,thepositiveeffectofinclusioncomplexformationonthe releaseprofilesofNAPinadditiontonanofiberincorporationhas beendemonstratedandthismaybeapromisingresultfordesigning noveldrugdeliverysystems.

4. Conclusions

Themainideabehindthisstudywastocomparetheefficiencies oftwodifferentdeliverysystemsfortheNAP;directincorpora- tionofNAPandNAPincludedcomplexincorporationfollowingIC formationwith␤CDintoelectrospunPCLnanofibers.Initially,the formationofNAP-␤CD-ICwasstudiedandthentheincorporation ofNAPandNAP-␤CD-ICintoPCLnanofiberswasperformedvia electrospinning.ThereleaseperformanceoftheNAPwasincreased morethantwotimesincaseofPCL/NAP-␤CD-ICnanofiberswhen comparedwithPCL/NAP nanofibers.Thus, it is understoodthat incorporationofNAP-␤CD-ICinapolymericnanofibroussystem stillpreservetheimprovedsolubilityeffectofCD-IContherelease rateofNAPandprovidesastableenvironmentforit.

Acknowledgment

StatePlanningOrganization(DPT)ofTurkeyisacknowledged for the support of UNAM-National Nanotechnology Research Center, BilkentUniversity. Dr. T. Uyar acknowledges TUBITAK- The Scientiﬁc and Technological Research Council of Turkey (project#111M459)andEUFP7-PEOPLE-2009RGMarieCurie-IRG (NANOWEB,PIRG06-GA-2009-256428)andTheTurkishAcademy ofSciences-OutstandingYoungScientistsAwardProgram(TUBA- GEBIP)for funding the research. A. Celebioglu acknowledges TUBITAK-BIDEBforthenationalPh.D.studyscholarship.

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