Research Article Physicochemical Characterization and ...downloads.hindawi.com/journals/tswj/2014/219035.pdf · Research Article Physicochemical Characterization and Thermodynamic

Research ArticlePhysicochemical Characterization andThermodynamic Studies of Nanoemulsion-BasedTransdermal Delivery System for Fullerene

Cheng Loong Ngan1 Mahiran Basri12 Minaketan Tripathy34

Roghayeh Abedi Karjiban1 and Emilia Abdul-Malek1

1 Department of Chemistry Faculty of Science Universiti Putra Malaysia 43400 Serdang Selangor Malaysia2Halal Products Research Institute Universiti Putra Malaysia 43400 Serdang Selangor Malaysia3 Laboratory of Fundamentals of Pharmaceutics Faculty of Pharmacy Universiti Teknologi MARA (UiTM) Puncak Alam Campus42300 Selangor Malaysia

4 Brain and Neuroscience Communities of Research Universiti Teknologi MARA (UiTM) 40450 Shah Alam Selangor Malaysia

Correspondence should be addressed to Cheng Loong Ngan clngan88yahoocom and Mahiran Basri mahiranupmedumy

Received 24 March 2014 Accepted 25 June 2014 Published 3 August 2014

Academic Editor Roberto Rivelino

Copyright copy 2014 Cheng Loong Ngan et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

Fullerene nanoemulsions were formulated in palm kernel oil esters stabilized by low amount of mixed nonionic surfactantsPseudoternary phase diagrams were established in the colloidal system of PKOEsTween 80 Span 80water incorporated withfullerene as antioxidant Preformulation was subjected to combination of high and low energy emulsification methods and thephysicochemical characteristics of fullerene nanoemulsions were analyzed using electroacoustic spectrometer Oil-in-water (OW)nanoemulsions with particle sizes in the range of 70ndash160 nm were formed The rheological characteristics of colloidal systemsexhibited shear thinning behavior which fitted well into the power law model The effect of xanthan gum (02ndash10 ww) andbeeswax (1ndash3 ww) in the estimation of thermodynamics was further studied From the energetic parameters calculated for theviscous flow a moderate energy barrier for transport process was observed Thermodynamic study showed that the enthalpy waspositive in all xanthan gum and beeswax concentrations indicating that the formation of nanoemulsions could be endothermicin nature Fullerene nanoemulsions with 06 or higher xanthan gum content were found to be stable against creaming andflocculation when exposed to extreme environmental conditions

1 Introduction

Nanoemulsions are non-equilibrium colloidal systemsformed by forcing two immiscible liquids into homogeneousstate which is kinetically stable with particle size rangingfrom 20 to 200 nm [1] Unlike microemulsions both systemscan be distinguished in terms of their thermodynamicstabilities where microemulsions are thermodynamicallystable whereas nanoemulsions are thermodynamicallyunstable The use of nanoemulsions in efficient deliveryof active ingredients or drugs into human body has beenwidely investigated There are many areas such as pharmacy

cosmetics and food technologies as well as non-medical-related products such as polymers and pesticides whichutilize the concept of nanoemulsification In fact most of thedrugs are lipophilic in nature [2] and oil-in-water (OW)type of emulsion is widely developed over the water-in-oil(WO) emulsion where oil acts as carrier for drugs

In drug delivery system toxicity of the final productdepends on the ingredients which constitute the emulsionsystem Microemulsions have a presence of noxious cosur-factant and higher concentration of surfactant that leadsto unwanted toxicity whereas nanoemulsions are devoidof such disadvantage Nonionic surfactants have prominent

Hindawi Publishing Corporatione Scientific World JournalVolume 2014 Article ID 219035 12 pageshttpdxdoiorg1011552014219035

2 The Scientific World Journal

advantages as compared to anionic or cationic surfactants inregard to lesser toxicity and biodegradability [3 4] Previ-ously several studies on the thermodynamics of microemul-sions with different mixed surfactant ratios and types ofcosurfactant were reported [5 6] A thorough literature studyshowed that limited attempts have been made with regard tothe thermodynamics of nanocolloidal systems in the presenceof rheological modifiers like hydrocolloid gums

The present study intends to develop a novel nanoemul-sion for transdermal application using palm kernel oil estersas biocompatible carrier for fullerene The core of this studyis based on characterization of physicochemical behaviorof the developed system in emphasizing the involved ther-modynamic Fullerene is a hydrophobic molecule composedentirely of carbon atoms which are interconnected to eachother via single and double bonds forming a spherical shape[7] Large production of fullerene via Kratschmer-Huffmanarc process [8] and discovery of its indication as a power-fulpotential antioxidant have attracted many investigations[9ndash11]

There have been a number of reports indicating the utilityof fullerene and its derivatives in oxidative stress-relateddiseases such as HIV Parkinsonrsquos disease and allergy [12ndash14] as well as in cosmetics [15ndash17] with no acute or subacutetoxicity to human body [18ndash21] The excellent antioxidantproperty of fullerene may be linked to its capability to breakthe C=C bonds thereby yielding the corresponding radicaladducts [9 10] or by catalytic dismutation [22] Besidesmedicinal applications fullerenes are also used in DNAphotocleavage enzyme inhibition and antimicrobial activityand as contrast agent or radiotracer [23]The primary advan-tages of transdermal antioxidant using fullerene incorporatednanoemulsions could be of a direct application in protectingthe human skin that is exposed to ultraviolet (UV) radiationPotential skin irritation can be avoided due to the presenceof lower concentration of surfactants as compared to that inmicroemulsions

In this study the physical and structural aspects offullerene nanoemulsions comprised of mixed nonionic sur-factants and palm kernel oil esters which are presented hereDifferent formulations of fullerene stabilized by xanthan gumwere prepared by using combination of high and low energyemulsification techniquesThe physicochemical properties ofthe novel formulations were characterized with an emphasison the thermodynamic and flow behavior

2 Materials and Methods

21 Materials Powdered fullerene (C60) with 995 purity

xanthan gum from Xanthomonas campestris white beeswaxpolyoxyethylene sorbitan monooleate (Tween 80) and sor-bitan monooleate (Span 80) were purchased from Sigma-Aldrich (St Louis USA) The average molecular weight ofxanthan gum was estimated as 152 kDa [24] Palm kernel oilesters (PKOEs) were synthesized in our laboratory throughenzymatic transesterification of palm kernel oil and oleylalcohol using Lipozyme RM IM as the catalyst [25] The fattyacid composition of PKOEs is shown in Table 1 Preservative

Table 1The percentage of fatty acid composition in palm kernel oilesters

Palm kernel oil esterscomposition

(number of carbonatoms number ofdouble bonds)

Percentage ()

Oleyl caproate C24 1 05Oleyl caprate C26 1 56Oleyl caprylate C28 1 59Oleyl laurate C30 1 541Oleyl myristate C32 1 139Oleyl palmitate C34 1 62Oleyl stearate C36 1 12Oleyl oleate C36 2 64Oleyl linoleate C36 3 17

phenonip was obtained from Bramble Berry (BellinghamUSA) Deionized water was purified using Milli-Q watersystem (Billerica USA)

22 Construction of Pseudoternary Phase Diagrams Fulle-renes were assayed at 160 120583gg of PKOEs by stirring usingmagnetic stirrer at 400 rpm for 24 h at room temperature(2980 plusmn 05 K) Mixture of fullerene solution with Tween80 was filled in 11 screw-cap vials at different ratios (ww)of 10 0 9 1 8 2 7 3 6 4 5 5 4 6 3 7 2 8 1 9 and0 10 respectively Deionized water 5 (ww) was addedeach time into the vials containing mixtures All componentswere weighed using analytical balance (Dragon 204 MettlerToledo Spain) and microbalance (CPA2P Sartorius Ger-many) Capwas tightened and homogenized for 20min usinga vortex mixer equipped with flask accessory (VTX-3000LUzusio Japan) Subsequently the samples were centrifuged(Hermle Labor Technik Germany) at 4000 rpm for 15min toobserve any phase separation through cross polarized platesfor visual identification of physical appearances The abovesteps were repeated with consecutive addition of 5 (ww)deionized water

The phase behavior study for mixed surfactant system(Tween 80 Span 80) was conducted The pseudoternaryphase diagram was constructed at room temperature (2980plusmn 05 K) and was plotted using SigmaPlot version 12 by SystatSoftware Inc (San Jose USA) Classification of phase statewas made according to the physical appearance observedwhich was categorized into isotropic homogeneous and twoor multiphase regions

23 Hydrophilic-Lipophilic Balance (HLB) An approachusing HLB concept an empirical parameter was appliedto determine the hydrophilic and hydrophobic content ofsurfactants and was used to study the phase behavior of themixtures This method aims to achieve the required HLBvalue for a given oil to obtain stable emulsion system HighHLB value indicates high hydrophilicity of the surfactantsystem or vice versa The HLB values of mixed binary

The Scientific World Journal 3

surfactant systems were calculated by Griffinrsquos formula whichwas applicable to nonionic surfactants as shown in [26]

HLBmix=wt of surfactant 119860

100times (HLB

119860minusHLB

119861) +HLB

119861

(1)

24 Selection of PreformulationConcentrates Preformulation(Pre-F) was selected from the pseudoternary phase diagramsbased on the following

(i) low percentage of surfactant to avoid potentialadverse toxicology and dermatology effects [27]

(ii) appreciable percentage of dispersed phase (oil phase)to favor the formation ofOWemulsion systemwhichgained the consumer acceptance for most skin careproducts

25 Preparation of Fullerene Nanoemulsions (FNEs) SelectedPre-F was prepared using high energy followed by lowenergy emulsification technique Formulations with xanthangum at varying concentrations of 02 04 06 08 and10 (ww) and beeswax concentrations of 1 2 and 3(ww) were prepared 07 (ww) of phenonip was addedinto the formulations as antimicrobial agent Nanoemulsionswere prepared by stirring oil and aqueous phase separatelyat 400 rpm at 373K to fully dissolve all the ingredientsThe oil phase was added slowly into the aqueous phaseand homogenized at 4000 rpm for 15min using a highshear homogenizer (PT3100 Kinematica AG Switzerland)The emulsions formed were then cooled down to roomtemperature (298 plusmn 2K) while stirring at 200 rpm using anoverhead stirrer (RW20 digital IKA-Werke Germany)

26 Acoustic and Electroacoustic Spectroscopy The FNEsmean droplet size was measured using acoustic and elec-troacoustic spectrometer (DT-1200 Dispersion TechnologyUSA) equipped with electroacoustic probes and a stirrer Itallows the determination of the distribution and the dropletsize down to the nanometer range During the measurementprocess parameters such as ultrasonic attenuation soundvelocity and acoustic impedance could be determined atdifferent frequencies The mathematical modeling of thesemeasurements results in the calculation of the droplet sizeWith electroacoustic spectroscopy it is unnecessary to carryout sample dilution which allows the characterization of thereal concentrated dispersions Sample dilution will alter theoverall system properties of the emulsion due to the changesin actual percentage composition of each component 100mLof FNEs was loaded into the spectrometer chamber Theparameters of Debye length and dynamic mobility of theFNEs droplets were also determined with the software pro-vided by feeding the respective conductance data

27 Characterization Studies of FNEs The viscosity of col-loidal systems was measured using a dynamic shear rheome-ter (Kinexus rotational rheometer Malvern Instrument UK)at a fixed shear rate of 01 sminus1 and at 4 different temperatures

(298 303 308 and 313 K)Themeasurementswere performedwithin 24 h after sample preparation using cone and plategeometry (4∘40mm) the gap being set at 015mm Sampleswere loaded and left for 5min to equilibrate before carryingout the measurement Viscosity of each sample was recordedin Pa s at an interval of 5 s till 60 data points are generatedand the average viscosity value was calculated Low viscositysamples were measured using a viscometer (LV BrookfieldUSA) equipped with plate geometry (CP43) at a controlledshear rate of 100 rpm The gap between the cone and theplate geometry was 002mm Viscosities of each samplewere recorded at an interval of 15 s till 20 data points aregenerated and the average viscosity was taken as the viscosityof the compositions In order to avoid any instrumental errorcalibration was carried out first by measuring the viscosity ofwater

The rheological behavior of fullerene-based colloidalsystems was examined at varying controlled shear rate modefrom 01 to 100 sminus1 at 298K FNEs were subjected to centrifu-gation at 2000 rpm for 2min to get rid of any air pocketspresent within the emulsion before loading onto the plateThe rheograms obtained were analyzed using power lawmodel

120590 = 119870 sdot 120574119899 (2)

where 120574 is the shear rate (sminus1) 119899 is the flow behaviorindex (dimensionless) 120590 is the shear stress (Pa) and 119870 isconsistency index (Pa s119899)

Densities of FNEs were measured at four differenttemperatures (29815 30315 30815 and 31315 K) using adensitometer (DM2911 Rudolph Analytical Research USA)Sample was injected slowly into the valve where the samplemoves through the glass tube to ensure that no air pocketwas trapped along the tube The densitometer was calibratedby using pure water and dry air The densities have precisionltplusmn10minus5 kgmminus3The pH values of FNEsweremeasured using apH meter (S20-SevenEasy Mettler Toledo Switzerland) andthe conductivities of FNEs were measured using a conductiv-ity meter (SG3-SevenGo Mettler Toledo Switzerland) Cali-bration was carried out using different pH buffer solutions(pH 4 7 and 10) and conductivity standards (1413 120583Scm and1288mScm) provided by the manufacturer respectively Toobtain a representative sample 20 strokes were performed toexpose the probe to sample before running themeasurementAll measurements were carried out repetitively five times at298K and the measurements were reported as the averagevalue of five readings

28 Accelerated Stability Study An accelerated storage test-ing was carried out to predict the long-term physical stabilityof the nanoemulsions Samples were subjected to centrifugalforce of 4000 rpm for 15min In the thermal stress test FNEswere kept at storage temperatures of 298K and 318K for90 days FNEs were also tested for freeze-thaw cycles byadding 5mL of samples into thin-walled glass tubes whichwere allowed to freeze at 269K for 24 h and thawed at roomtemperature for another 24 hThe above step was repeated for


PKOEs Flln 0 10 20 30 40 50 60 70 80 90 100

Tween 80

0

10

20

30

40

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60

70

80

90

1000

10

20

30

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50

60

70

80

90

100H2O

(a)

PKOEs Flln0 10 20 30 40 50 60 70 80 90 100

Tween 80 Span 80(9 1)

0

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1000

10

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100H2O

(b)

0 10 20 30 40 50 60 70 80 90 100

Tween 80 Span 80 (8 2)

0

10

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60

70

80

90

1000

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Pre-F tested

H2O PKOEs Flln

(c)

PKOEs Flln0 10 20 30 40 50 60 70 80 90 100


0

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70

80

90

1000

10

20

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90

100H2O

(d)

Figure 1 Pseudoternary phase diagram of PKOEs fullerene (Flln)Tween 80 Span 80Water in the MSRs of (a) 10 0 (b) 9 1 (c) 8 2 and(d) 7 3 at 298K ◼ = Isotropic e = Homogeneous 998787 = Two-phase

three cycles Visual assessment under cross polarized plateswas done to evaluate the physical appearance of the samples

3 Results and Discussion

31 Phase Behavior of PKOEs FullereneSurfactant(s)WaterSystem The pseudoternary phase diagram was constructedon the basis of initial experiments to show the relation-ship between composition involving PKOEs fullerene sin-gle surfactant (Tween 80) and water using minimumenergy through vortexing The phase-forming behavior ofthe PKOEs fullereneTween 80water system at 298K ispresented in Figure 1(a) Classification of regions was madebased on optical visualization through cross polarized platesafter centrifugation process The appearance of single phaselies in the isotropic region with transparent monophasicliquid whereas the homogeneous region was identified as

milkycloudy white liquid The remaining region representsthe two-phase region which has two distinct layers of liq-uidgel phases It was observed that oil surfactant ratio at10 0 9 1 and 8 2 at all water percentages showed isotropicsystem but started to exhibit homogeneous system at ratio of7 3 Nonetheless the application of the single surfactant didnot produce large enough monophasic region

Mixture of surfactants was used instead of a single surfac-tant This combination of surfactants exhibited better perfor-mance in many industrial applications [28 29] Combinationof Tween 80 and Span 80 has high compatibility to build astable interfacial film and give better performance in emulsi-fication process in most of the studies [30ndash32] Small amountof Span 80 assisted in reducing the interfacial tension betweenoil and water and in acquiring tighter molecular packingbetween the surfactant molecules at the oil-water interfaceThe phase-forming behavior of the PKOEs fullereneTween


Table 2 Calculated hydrophilic-lipophilic balance (HLB) values ofthe nonionic surfactants in the single and binary surfactant systems

Surfactantmixed surfactant HLB numberTween 80 1500Span 80 430Tween 80 Span 80 (9 1) 1393Tween 80 Span 80 (8 2) 1286Tween 80 Span 80 (7 3) 1179

80 Span 80water system at three different mixed surfactantratios (MSRs) of 9 1 8 2 and 7 3 at 298K is presented inFigures 1(b) 1(c) and 1(d) respectively

TheHLB values of single and binary surfactant systems ofTween 80 and Span 80 relating to the formation of monopha-sic region in the pseudoternary phase diagram are shownin Table 2 The increasing of Span 80 content in the mixedsurfactant system at MSR from 9 1 to 8 2 increased themonophasic region but it was reduced dramatically at MSRof 7 3The largest monophasic region formation was noticedusingmixed surfactant systemTween 80 Span 80 (MSR 8 2)with HLB of 1286 The optimized HLB value obtained frommixed surfactants displayed that the enhanced flexibility ofsurfactant layer is able to partition itself efficiently at the oil-water interface Mixed surfactants were found to increasethe monophasic region where it shifted towards the oil-richcorner of the phase diagrams This indicated that higher oilconcentration was incorporated within the system than thesingle surfactant did The synergistic effect of the surfactantmolecules interaction was due to the mixed micelles for-mation which enhanced the solubilization capacity with theincrease in hydrophobicity of the binary surfactant systems[33]

As seen in Figure 1(c) the isotropic phases were locatedalong the oil-surfactant axes at any ratio indicating thetotal solubility between the two components which wasconsistent with previous studies [31 34] Without the pres-ence of water oil phase was able to merge completelyinto the surfactant with the lipophilic tail of surfactantmolecules arranging themselves towards the oil phase Thelarge isotropic region which appeared at the rich surfactantarea allowed the formation of micellar solution or water-in-oil (WO) microemulsion As the dominant species aremainly surfactant molecules relative amount of oil phaseis rearranged within the surfactant vesicleslayers where thehydrophilic head usually surrounds the oil phase When thetotal amount of surfactant used decreased to less than 40(ww) in the system transition took place from isotropicto homogeneous state immediately The oil phase startedto break into individual droplets where water started totake over to become the continuous phase The systemevolved from water-in-oil (WO) to an oil-in-water (OW)structure whereby in the homogeneous state it showed lowerstability than the isotropic due to its polydispersityThe phaseequilibrium for two-phase region was not determined Basedon the results and reference [35] a Pre-F composed of 20PKOEs fullerene 5mixed surfactants (ie Tween 80 Span80 8 2) and 75 water was chosen for further studies

32 Characterization of FNEs Themean droplet size of FNEswith different components concentration ranged from 70 to160 nm with fitting error less than 5 as tabulated in Table 3According to Dukhin and Fairhurst the emulsion comprisesprimarily of very small droplet size as large droplets arebroken down due to high shear homogenisation and witha fraction of larger droplets indicating smaller droplets arecoalescing [36] By using acoustic measurements dynamicchanges in the state of an emulsion can be followed in realtime It was observed that the droplet size increased with theincrease of xanthan gum concentration to 04 (ww) butstarted to maintain its size around 100 to 130 nm at higherconcentration These results indicated that concentration of04 (ww) xanthan gum and below was not able to estab-lish secondary layer to completely surround the emulsiondroplets instead it induced the fusion of emulsion dropletsdue to depletion forces [37] However formulations withhigher xanthan gum concentration were able to keep thedroplets away from each other by forming steric stabilizingpolymer-coated droplets due to the sufficient polymer chainto cover the surface of oil droplets [38] This suggests that aminimum xanthan gum concentration is needed to form apolymer network that is capable of maintaining the dropletsapart [39 40] Pre-F and FNE1 showed the smallest dropletsize because they exhibit perfect collision during Brownianmotion for limited period of time In the absence of xanthangum the emulsification process will not be affected by therestriction of the high viscosity xanthan gum thus no smallerdroplet will be observed

The pH of a healthy human skin on average is 55 [41]In Table 3 the results showed that all formulations werecompatible with human skin with plusmn15 variation in pH whichis suitable for human applicationwithout affecting the naturalpH of human skin In Figure 2(a) the electrical conductivityof FNEs was observed to increase with increasing xanthangum concentration but decrease with increasing beeswaxconcentration A similar observationwas reported by a previ-ous study [42]With the absence of xanthan gumandbeeswaxin the colloidal systems the electrical conductivity of Pre-Fand FNE1 measured is 554 and 638 120583Scm A sharp increasein electrical conductivity is observed with the incorporationof xanthan gum into the system and this may be due to thenature of xanthan gum as an anionic polysaccharide Theeffect of xanthan gum and beeswax concentration on surfacecharge is also depicted in Figure 2(b) In terms of surfacecharge of emulsion droplets the surface charge increases withincreasing xanthan gum concentration but decreases slowlywith increasing beeswax concentration

The electrical conductivity of the FNEs is also related tothe ability of emulsion droplets to conduct an electric currentwhich correlates to their mobility The dynamic mobilityof the colloidal systems is presented in Figure 2(c) It isevident from Figure 2(c) that the dynamic mobility of thecolloidal systems decreaseswith the increase in concentrationof xanthan gum However the addition of beeswax decreasesthe mobility of the oil droplet The increase in beeswaxconcentration increases the mobility of the oil dropletThe Debye length of the colloidal systems ranging from448 to 820 nm is plotted in Figure 2(d) Debye length for


Table 3 Composition and physicochemical characteristics of FNE formulations

Formulation Components concentration ( ww) Diameter(plusmnstandard deviation)

(nm)pH

PKOEs Tween 80 Span 80 Phenonip Xanthan gum Beeswax WaterPre-F 20 4 1 0 0 0 750 897 plusmn 010 570FNE1 20 4 1 07 0 0 743 728 plusmn 005 560FNE2

(a) 20 4 1 07 02 0 741 1127 plusmn 012 566(b) 20 4 1 07 04 0 739 1335 plusmn 012 564(c) 20 4 1 07 06 0 737 1045 plusmn 013 553(d) 20 4 1 07 08 0 735 909 plusmn 010 547(e) 20 4 1 07 10 0 733 1136 plusmn 011 536

FNE3(a) 20 4 1 07 02 1 731 1152 plusmn 013 565(b) 20 4 1 07 04 1 729 1448 plusmn 008 561(c) 20 4 1 07 06 1 727 949 plusmn 011 555(d) 20 4 1 07 08 1 725 986 plusmn 010 554(e) 20 4 1 07 10 1 723 998 plusmn 015 540



Pre-F and FNE1 was 1556 and 1452 nm respectively Withthe introduction of xanthan gum into the colloidal system theDebye length reduced drastically The Debye length is foundto increase with increasing the concentration of both xanthangum and beeswax These findings point to the fact thatxanthan gum and beeswax can work efficiently as viscosityenhancers through controlling the Brownian motion onlyabove certain concentration Further the observations relatedto dynamic mobility and that of the Debye length arecomplementing each other in this case

33 Shear Viscosity of the FNEs The shear viscosities 120578 ofFNEs were measured at controlled shear rate at four differenttemperatures 298 303 308 and 313 K The shear rate thatwas chosen to be operated on the rheometerviscometergave the maximum percentage of torque indicating the highaccuracy of reading In Figure 3 the viscosities of FNEsincreased with the increase in concentration of xanthan gumand beeswax Nevertheless the viscosities decreased withthe increase in temperature The increase in temperatureenhances the thermal energy of the system thereby causing

the oil droplet to vibrate and travel faster in Brownianmotionwithin the aqueous medium thus easier for the emulsionto flow Based on Arrhenius equation there is an inverserelationship between the viscosity and the temperature [43]

120578 = 120578119900exp (

119864119886

119877119879) (3)

where 120578119900is a constant 119864

119886is the activation energy 119879

is the absolute temperature and 119877 is the gas constant(8314 KJmolminus1) Figure 3 shows that the viscosities of theformulations decrease with increase in temperature withinthe systems which was found to be adequately described bythe Arrhenius equation Another reason can be also relatedto the loose packing between polymer chains which can causemore space for the polymer chain to slip through

Steady shear flow properties of FNEs with different com-positions of xanthan gum and beeswax concentrations weremeasured over a range of shear rates The flow behaviors ofFNEs are particularly important to predict the end-productrsquostexture attribute and to ease the industrial handling processessuch as flow pump and agitation tank [43] Figure 4 shows


0

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duct

ivity

(120583S

cm)

[Beeswax] ( ww)

(a)

000

002

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ce ch

arge

(10minus6c

m2)

(b)

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0 1 2 3 4

Dyn

amic

mob

ility

(120583m

sV

cm

)

[Beeswax] ( ww)

10 (ww)08 (ww)06 (ww)

04 (ww)02 (ww)

Xanthan gum

(c)

10 (ww)08 (ww)06 (ww)

04 (ww)02 (ww)

Xanthan gum

0

2

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6

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0 1 2 3 4

Deb

ye le

ngth

(nm

)

[Beeswax] ( ww)

(d)

Figure 2 Effects of beeswax and xanthan gum concentration on (a) electrical conductivity (b) surface charge (c) dynamic mobility and (d)Debye length of FNEs

the shear rate dependence of the apparent viscosity for FNEswith 04 06 08 and 10 (ww) xanthan gum The flowbehavior of FNEs could be well described by the power lawmodel As the flowbehavior index 119899 gets less than 1 themorepronounced is the shear thinning behavior (pseudoplastic)which exhibits non-Newtonian behavior [44] Table 4 showsthe values of power law parameters obtained by linearregression analysis The data exhibited 119899 values less than 03with 1198772 values higher than 0970 in all FNEsThe consistencyindex was also increased with the increase of xanthan gumconcentration demonstrating the strengthening in structureformation of nanoemulsion systems [45] It was clearly shownthat the apparent viscosity decreased as the shear rate wasincreased for all FNEs due to the breakdown of colloidalstructure [46] Initially when low shear rate was applied

xanthan gumwhichwas composed of largemolecules formeda polymer network structure surrounding the oil dropletsthrough hydrogen bonding between xanthan gummoleculesthus resulting in high shear viscosity of FNEs It was reportedthat upon application of high shear rate the flow of theemulsion droplets tended to align with the direction of theshear flow hence disentangling the polymer network andreducing the apparent viscosity of the samples [45]

The activation enthalpy Δ119867lowast for the viscous flow of theinvestigated nanocolloidal systems was estimated accordingto the following equation

120578 = (119873ℎ

120592) exp(

Δ119867lowast

vis119877119879

) exp(minusΔ119878lowast

vis119877

) (4)


Table 4 Power law model parameters for selected FNE formulations

FormulationComponents concentration

( ww) Consistency coefficients 119870 (Pa s119899) Flow behavior indices 119899 Regressioncoefficients R2

Xanthan gum BeeswaxFNE3

(b) 04 1 3173 0202 0983(c) 06 1 7305 0144 0976(d) 08 1 9438 0137 0988(e) 1 1 1249 0147 099

FNE4(b) 04 2 4318 0217 0981(c) 06 2 8742 0104 098(d) 08 2 1032 0137 0971(e) 1 2 1578 0132 0984

FNE5(b) 04 3 5247 019 0986(c) 06 3 8886 0143 0981(d) 08 3 1102 0141 098(e) 1 3 2132 0095 0974

0

20

40

60

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100

120

298

303

308

3130204

0608

10

Visc

osity

(Pa s

)

Tempe

ratur

e (K)

[Xanthan gum] ( ww)

Figure 3 Viscosities of Pre-F and FNEs at different temperatureswith varying concentration of xanthan gum containing 0 (e) 1(I) 2 (998787) and 3 (Δ) of beeswax

or

ln 120578 = [ln(119873ℎ120592) minus

Δ119878lowast

vis119877

] +Δ119867lowast

vis119877119879

(5)

where ℎ119873 120592 andΔ119878lowastvis are Plankrsquos constant Avogadrorsquos num-ber molar volume and entropy of activation respectively In(5) the first term in the right hand side (in the bracket) hasa constant value So the values of Δ119867lowastvis can be determinedfrom the slope of the nonlinear plot of ln 120578 versus 119879 Hence

01

1

10

100

1000

01 1 10 100 1000

Appa

rent

visc

osity

(Pa s

)

Shear rate (1s)

10 (ww)08 (ww)

06 (ww)04 (ww)

Xanthan gum

Figure 4 Shear rate dependence of steady shear viscosity forFNEs with 1 (ww) of beeswax with different xanthan gumconcentrations

the relationship between ln 120578 and119879 can be expressed in termsof a polynomial as follows

ln 120578 = 119886 + 119887119879 + 1198881198792 (6)

and the values of Δ119867lowastvis can be obtained from its derivativewith respect to 119879 followed by

119889 ln 120578119889119879

=minusΔ119867lowast

vis

1198771198792

= 119887 + 2119888119879 (7)


Table 5 Temperature-dependent activation parameter for PKOEsTween 80 Span 80water systems

FormulationΔH (kJmolminus1) ΔG (kJmolminus1) Δ119878 (J Kminus1molminus1)Temperature K Temperature K Temperature K

298 303 308 313 298 303 308 313 298 303 308 313Pre-F 238 162 80 minus07 388 384 381 379 minus505 minus753 minus1016 minus1291FNE1 961 673 364 33 399 387 384 383 1886 920 minus107 minus1178FNE2

(a) 476 293 98 minus111 576 565 560 555 minus338 minus929 minus1561 minus2216(b) 989 802 599 383 609 598 585 581 1275 637 minus17 minus727(c) 1075 821 549 257 629 617 609 606 1496 641 minus263 minus1213(d) 1082 692 273 minus174 640 625 622 620 1483 185 minus1200 minus2638(e) 817 608 383 143 647 639 633 633 571 minus137 minus880 minus1666

FNE3(a) 528 592 659 729 578 571 563 554 minus168 37 250 469(b) 917 719 506 279 613 600 595 590 1020 360 minus354 minus1090(c) 965 723 463 185 632 618 612 607 1118 311 minus550 minus1447(d) 1070 770 449 105 641 628 622 621 1440 433 minus631 minus1748(e) 910 658 388 99 650 641 635 635 870 22 minus871 minus1812

FNE4(a) 633 647 660 674 579 572 564 557 180 215 252 284(b) 690 522 342 150 614 604 597 593 253 minus304 minus891 minus1510(c) 812 588 347 90 635 622 616 611 595 minus147 minus941 minus1764(d) 981 739 480 202 643 631 626 623 1134 320 minus543 minus1445(e) 783 604 411 204 652 643 638 636 442 minus166 minus807 minus1482

FNE5(a) 680 611 537 457 582 575 567 562 327 88 minus158 minus427(b) 837 621 389 141 619 606 600 595 731 16 minus752 minus1547(c) 952 687 402 98 639 626 621 618 1053 166 minus776 minus1761(d) 817 600 368 119 644 635 633 631 579 minus149 minus930 minus1738(e) 735 561 375 175 652 644 639 637 276 minus310 minus927 minus1578

where 119886 119887 and 119888 are the fitting parameters obtained by thecomputational method

The values of molar volume were kept constant as theexperimental densities of the nanocolloidal systems showedvery insignificant dependence over temperature Further-more the values of Δ119867lowastvis were used to calculate the entropyof activation followed by Gibbs free energy equation

Δ119878lowast

vis =(Δ119867lowast

vis minus Δ119866lowast

vis)

119879 (8)

where the values of Δ119866lowastvis were estimated by

Δ119866lowast

vis = 119877119879 ln(120578120592

119873ℎ) (9)

The activation parameters for FNEs with different com-positions are tabulated in Table 5 Δ119866lowastvis and Δ119867lowastvis valueswere positive in most formulations which was similar toother transport processes [5] It is seen that the addition ofxanthan gum resulted in a longitudinal decrease in the valuesof enthalpy whereas the reverse was the case with the increasein temperature The positive Δ119878lowastvis value with increasingxanthan gum concentration for all compositions indicated

thatmore polymer chains were crowded at the interface of theemulsion droplet thus suggesting structure enhancement ofthe emulsion FNEs composed of 10 xanthan gum behavedin an order system by showing lowest Δ119878lowastvis which forma colloidal network spreading through the entire systemwhich contribute to the improved stability However in allcases the Δ119878lowastvis values were gradually increased with theincrease of temperature indicating that microscopic dropletsscatter much frequently creating disorder arrangement in thecolloidal system due to the increase in kinetic energy

34 Accelerated Stability Study Assessment of long-termstability of FNEs shelf life under environmental storageconditions can be very tedious and time consuming whichis considered uneconomical The development of productsought to be fast-paced yet reliable to meet the demand of theconsumers Thus FNEs were let to experience a variation ofextreme storage conditions to predict the samplesrsquo ability towithstand over a period of time Centrifugation can acceleratethe rate of creaming or sedimentation which demonstratesthat the breakdownof an emulsion can be related to the actionof gravitational force OW emulsion system often exhibitscreaming rather than sedimentation due to the lower density


Table 6 Accelerated stability assessment of the Pre-F and FNEs

Formulation Centrifugation test at4000 rpm for 15min

298K 318K Freeze-thawcycles

Pre-F M mdash mdash MFNE1 M mdash mdash MFNE2

(a) M

(b) M

(c)

(d)

(e)

FNE3(a) M

(b) M

(c)

(d)

(e)

FNE4(a) M

(b) M

(c)

(d)

(e)

FNE5(a) M

(b) M

(c)

(d)

(e)

Note stable (without phase separation) M unstable (with phase separa-tion)

of the oil droplet compared to the aqueous medium Theresult of the accelerated stability study of FNEs is shown inTable 6 Changes of physical appearance were also observedupon completion of the centrifugation process Pre-F andFNE1 were found to be separated into two distinct layers(oil layer top aqueous layer bottom) upon centrifugationresulting from instability in the emulsion system Absenceof xanthan gum as a viscosity enhancer (thickener) in thecontinuous phase caused failure in resisting the movement ofthe oil droplet against the gravitational force

Sample storage at elevated temperature contributed tothe higher kinetic energy in the Brownian motion of the oildropletsThis is possibly to speed up themovement andmorecollision between the oil droplets at higher temperature OnlyFNEs which were stable against centrifugation were testedon storage at elevated temperature Our results showed thatFNEs with more than 06 xanthan gum (ww) were able

to maintain the homogeneity of the emulsion only up to 90days The phase separation decreases with the increase inxanthan gum concentration possibly due to the formation ofmore ordered polymer structure formed within the emulsionsystem

In the freeze-thaw cycle FNEs except Pre-F and FNE1were found to be stable by maintaining their homogenousstate On freezing the samples oil droplets segregated them-selves from the emulsion by the crystallized ice particleresulting in the disruption of lipid film surrounding thedropletsWhen the samples were thawed the droplets meltedand immediately coalesced between approaching dropletsresulting in oiling off from the emulsionswhichwas indicatedby phase separation However FNEs with xanthan gummaintained their homogeneity whereas Pre-F and FNE1(without xanthan gum) exhibited phase separation Xanthangum being dissolved in the water reduced the reassociation ofoil droplets and that phenomenon in the damaged networkled to less syneresis [47] Xanthan gum also reduced theformation of ice crystals Hence FNEs containing xanthangum were suitable to be stored at freezing temperature

4 Conclusions

Pseudoternary phase diagrams served as template to obtainemulsion-based preformulation and were further developedinto nanoemulsions with small particle size (lt200 nm) byhigh-low energy emulsification method Mixed surfactantsystems demonstrated better performance in obtaining largermonophasic zones compared to single surfactant systemThe relationship between viscosity and temperature of thefullerene nanoemulsions agreed well with Arrhenius equa-tion at all tested temperatures of 298ndash313 K In the presenceof xanthan gum fullerene nanoemulsions exhibited pseu-doplastic behavior The activation enthalpy for viscous flow(Δ119867lowastvis) was found to be composition dependent and theGibbs free energy of fullerene nanoemulsions containingxanthan gum and beeswax was more positive than thepreformulationThe stability of fullerene nanoemulsions wasxanthan gum content dependent which remained stable upto 90 days of storage period at elevated temperature Thismethodology can be used to understand and assess thestructural formation in the development of a highly stablenanoemulsion for transdermal delivery

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgment

The authors would like to acknowledge financial supportfrom Ministry of Higher Education (MOHE) Malaysiaunder the Fundamental Research Grant Scheme (FRGS) (02-01-13-1235FR) and My Brain15


References

[1] C Solans P Izquierdo J Nolla N Azemar and M J Garcia-Celma ldquoNano-emulsionsrdquo Current Opinion in Colloid andInterface Science vol 10 no 3-4 pp 102ndash110 2005

[2] G G Gibson and P Skett Introduction to Drug MetabolismNelsonThornes Cheltenham UK 2001

[3] F Volkering A M Breure J G van Andel and W H RulkensldquoInfluence of nonionic surfactants on bioavailability andbiodegradation of polycyclic aromatic hydrocarbonsrdquo Appliedand Environmental Microbiology vol 61 no 5 pp 1699ndash17051995

[4] E Jurado V Bravo J M Vicaria A Fernandez-Arteaga andA I Garcia-Lopez ldquoTriolein solubilization using highly biode-gradable non-ionic surfactantsrdquoColloids and Surfaces A Physic-ochemical and Engineering Aspects vol 326 no 3 pp 162ndash1682008

[5] A Acharya S P Moulik S K Sanyal B K Mishra and P MPuri ldquoPhysicochemical investigations ofmicroemulsification ofcoconut oil and water using polyoxyethylene 2-cetyl ether (Brij52) and isopropanol or ethanolrdquo Journal of Colloid and InterfaceScience vol 245 no 1 pp 163ndash170 2002

[6] R K Mitra and B K Paul ldquoPhysicochemical investigations ofmicroemulsification of eucalyptus oil and water using mixedsurfactants (AOT+Brij-35) and butanolrdquo Journal of Colloid andInterface Science vol 283 no 2 pp 565ndash577 2005

[7] H W Kroto J R Heath S C OrsquoBrien R F Curl and R ESmalley ldquoC

60 buckminsterfullerenerdquoNature vol 318 no 6042

pp 162ndash163 1985[8] W Kratschmer L D Lamb K Fostiropoulos and D R

Huffman ldquoSolid C60 a new form of carbonrdquo Nature vol 347

no 6291 pp 354ndash358 1990[9] P J Krusic E Wasserman P N Keizer J R Morton and K F

Preston ldquoRadical reactions of C60rdquo Science vol 254 no 5035

pp 1183ndash1185 1991[10] C N McEwen R G McKay and B S Larsen ldquoC

60as a radical

spongerdquo Journal of the American Chemical Society vol 114 pp4412ndash4414 1992

[11] C Wang L A Tai D D Lee et al ldquoC60 and water-solublefullerene derivatives as antioxidants against radical-initiatedlipid peroxidationrdquo Journal of Medicinal Chemistry vol 42 no22 pp 4614ndash4620 1999

[12] S H Friedman D L DeCamp R P Sijbesma G Srdanov FWudl and G L Kenyon ldquoInhibition of the HIV-1 protease byfullerene derivatives model building studies and experimentalverificationrdquo Journal of the American Chemical Society vol 115no 15 pp 6506ndash6509 1993

[13] L L Dugan E G Lovett K L Quick J Lotharius T T Lin andK L OrsquoMalley ldquoFullerene-based antioxidants and neurodegen-erative disordersrdquo Parkinsonism amp Related Disorders vol 7 no3 pp 243ndash246 2001

[14] J J Ryan H R Bateman A Stover et al ldquoFullerene nanomate-rials inhibit the allergic responserdquo Journal of Immunology vol179 no 1 pp 665ndash672 2007

[15] H Takada H Mimura L Xiao et al ldquoInnovative anti-oxidantfullerene (INCI 7587) is as ldquoradical spongerdquo on the skin Itshigh level of safety stability and potential as premier anti-agingand whitening cosmetic ingredientrdquo Fullerenes Nanotubes andCarbon Nanostructures vol 14 no 2-3 pp 335ndash341 2006

[16] S Kato H Taira H Aoshima Y Saitoh and N Miwa ldquoClinicalevaluation of fullerene-C

60dissolved in squalane for anti-

wrinkle cosmeticsrdquo Journal of Nanoscience andNanotechnologyvol 10 no 10 pp 6769ndash6774 2010

[17] S Inui H Aoshima A Nishiyama and S Itami ldquoImprovementof acne vulgaris by topical fullerene application unique impacton skin carerdquo Nanomedicine Nanotechnology Biology andMedicine vol 7 no 2 pp 238ndash241 2011

[18] N Gharbi M Pressac M Hadchouel H Szwarc S R Wilsonand F Moussa ldquoFullerene is a powerful antioxidant in vivo withno acute or subacute toxicityrdquo Nano Letters vol 5 no 12 pp2578ndash2585 2005

[19] T Mori H Takada S Ito K Matsubayashi N Miwa andT Sawaguchi ldquoPreclinical studies on safety of fullerene uponacute oral administration and evaluation for no mutagenesisrdquoToxicology vol 225 no 1 pp 48ndash54 2006

[20] H Aoshima Y Saitoh S Ito S Yamana and N MiwaldquoSafety evaluation of highly purified fullerenes (HPFs) basedon screening of eye and skin damagerdquo Journal of ToxicologicalSciences vol 34 no 5 pp 555ndash562 2009

[21] S Kato H Aoshima Y Saitoh and N Miwa ldquoBiologicalsafety of lipoFullerene composed of squalane and fullerene-C60 upon mutagenesis photocytotoxicity and permeabilityinto the human skin tissuerdquo Basic and Clinical Pharmacologyand Toxicology vol 104 no 6 pp 483ndash487 2009

[22] S S Ali J I Hardt K L Quick et al ldquoA biologically effectivefullerene (C

60) derivative with superoxide dismutase mimetic

propertiesrdquo Free Radical Biology amp Medicine vol 37 no 8 pp1191ndash1202 2004

[23] S Bosi T da Ros G Spalluto and M Prato ldquoFullerene deriva-tives an attractive tool for biological applicationsrdquo EuropeanJournal of Medicinal Chemistry vol 38 pp 913ndash923 2003

[24] A C Mendes E T Baran R C Pereira H S Azevedo and RL Reis ldquoEncapsulation and survival of a chondrocyte cell linewithin xanthan gum derivativerdquo Macromolecular Biosciencevol 12 no 3 pp 350ndash359 2012

[25] P S Keng M Basri M R S Zakaria et al ldquoNewly synthesizedpalm esters for cosmetics industryrdquo Industrial Crops and Prod-ucts vol 29 no 1 pp 37ndash44 2009

[26] V Verdinelli P V Messina P C Schulz and B VuanoldquoHydrophile-lipophile balance (HLB) of n-alkane phosphonicacids and theirs saltsrdquo Colloids and Surfaces A Physicochemicaland Engineering Aspects vol 316 no 1ndash3 pp 131ndash135 2008

[27] P Dykes ldquoSurfactants and the skinrdquo International Journal ofCosmetic Science vol 20 no 1 pp 53ndash61 1998

[28] M Borse V Sharma V K Aswal P S Goyal and S DevildquoAggregation properties of mixed surfactant systems of dimericbutane-14-bis(dodecylhydroxyethylmethylammoniumbromide) and its monomeric counterpartrdquo Colloids andSurfaces A Physicochemical and Engineering Aspects vol 287no 1amp3 pp 163ndash169 2006

[29] C B Fox ldquoSqualene emulsions for parenteral vaccine and drugdeliveryrdquoMolecules vol 14 no 9 pp 3286ndash3312 2009

[30] W Hou and K D Papadopoulos ldquoW1OW

2and O

1WO

2

globules stabilized with Span 80 and Tween 80rdquo Colloids andSurfaces A Physicochemical and Engineering Aspects vol 125no 2-3 pp 181ndash187 1997

[31] M Porras C Solans C Gonzalez A Martınez A Guinartand J M Gutierrez ldquoStudies of formation of WO nano-emul-sionsrdquoColloids and Surfaces A Physicochemical and EngineeringAspects vol 249 no 1ndash3 pp 115ndash118 2004


[32] K Bouchemal S Briancon E Perrier and H Fessi ldquoNano-emulsion formulation using spontaneous emulsification sol-vent oil and surfactant optimisationrdquo International Journal ofPharmaceutics vol 280 no 1-2 pp 241ndash251 2004

[33] B Zhao and L Zhu ldquoSolubilization of DNAPLs by mixedsurfactant synergism and solubilization capacityrdquo Journal ofHazardous Materials vol 136 no 3 pp 513ndash519 2006

[34] H Wu C Ramachandran N D Weiner and B J RoesslerldquoTopical transport of hydrophilic compounds using water-in-oil nanoemulsionsrdquo International Journal of Pharmaceutics vol220 no 1-2 pp 63ndash75 2001

[35] O Sonneville-Auburn J T Simonnet and F LAlloret ldquoNano-emulsions a new vehicle for skin care productsrdquo AdvancedColloid and Interface Science vol 108-109 pp 145ndash149 2004

[36] A S Dukhin and D Fairhurst Science and Applications ofSkin Delivery Systems Wissenschaftliche VerlagsgesellschaftStuttgart Germany 2008

[37] S Aben C Holtze T Tadros and P Schurtenberger ldquoRheo-logical investigations on the creaming of depletion-flocculatedemulsionsrdquo Langmuir vol 28 no 21 pp 7967ndash7975 2012

[38] V Kumar L Wang M Riebe H Tung and R K PrudrsquohommeldquoFormulation and stability of itraconazole and odanacatibnanoparticles governing physical parametersrdquoMolecular Phar-maceutics vol 6 no 4 pp 1118ndash1124 2009

[39] B Katzbauer ldquoProperties and applications of xanthan gumrdquoPolymer Degradation and Stability vol 59 no 1ndash3 pp 81ndash841998

[40] S Comba and R Sethi ldquoStabilization of highly concentratedsuspensions of iron nanoparticles using shear-thinning gels ofxanthan gumrdquo Water Research vol 43 no 15 pp 3717ndash37262009

[41] T Mahmood and N Akhtar ldquoStability of a cosmetic multipleemulsion loaded with green tea extractrdquo The Scientific WorldJournal vol 2013 Article ID 153695 7 pages 2013

[42] M Nedjhioui N Moulai-Mostefa A Morsli and A BensmailildquoCombined effects of polymersurfactantoilalkali on physicalchemical propertiesrdquo Desalination vol 185 no 1ndash3 pp 543ndash550 2005

[43] Z Xuewu L Xin G Dexiang Z Wei X Tong and MYonghong ldquoRheological models for xanthan gumrdquo Journal ofFood Engineering vol 27 no 2 pp 203ndash209 1996

[44] T Tadros ldquoApplication of rheology for assessment and predic-tion of the long-term physical stability of emulsionsrdquo Advancesin Colloid and Interface Science vol 108-109 pp 227ndash258 2004

[45] K W Song Y S Kim and G S Chang ldquoRheology of con-centrated xanthan gum solutions Steady shear flow behaviorrdquoFibers and Polymers vol 7 no 2 pp 129ndash138 2006

[46] P Rajinder ldquoYield stress and viscoelastic properties of highinternal phase ratio emulsionsrdquo Colloid and Polymer Sciencevol 277 no 6 pp 583ndash588 1999

[47] R Pongsawatmanit and S Srijunthongsiri ldquoInfluence of xan-than gum on rheological properties and freeze-thaw stability oftapioca starchrdquo Journal of Food Engineering vol 88 no 1 pp137ndash143 2008

Submit your manuscripts athttpwwwhindawicom

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CorrosionInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Polymer ScienceInternational Journal of



CeramicsJournal of


CompositesJournal of

NanoparticlesJournal of



International Journal of

Biomaterials


NanoscienceJournal of

TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Journal of

NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

CrystallographyJournal of


The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014


CoatingsJournal of

Advances in

Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Smart Materials Research



MetallurgyJournal of


BioMed Research International

MaterialsJournal of


Nano

materials


Journal ofNanomaterials


advantages as compared to anionic or cationic surfactants inregard to lesser toxicity and biodegradability [3 4] Previ-ously several studies on the thermodynamics of microemul-sions with different mixed surfactant ratios and types ofcosurfactant were reported [5 6] A thorough literature studyshowed that limited attempts have been made with regard tothe thermodynamics of nanocolloidal systems in the presenceof rheological modifiers like hydrocolloid gums

The present study intends to develop a novel nanoemul-sion for transdermal application using palm kernel oil estersas biocompatible carrier for fullerene The core of this studyis based on characterization of physicochemical behaviorof the developed system in emphasizing the involved ther-modynamic Fullerene is a hydrophobic molecule composedentirely of carbon atoms which are interconnected to eachother via single and double bonds forming a spherical shape[7] Large production of fullerene via Kratschmer-Huffmanarc process [8] and discovery of its indication as a power-fulpotential antioxidant have attracted many investigations[9ndash11]

There have been a number of reports indicating the utilityof fullerene and its derivatives in oxidative stress-relateddiseases such as HIV Parkinsonrsquos disease and allergy [12ndash14] as well as in cosmetics [15ndash17] with no acute or subacutetoxicity to human body [18ndash21] The excellent antioxidantproperty of fullerene may be linked to its capability to breakthe C=C bonds thereby yielding the corresponding radicaladducts [9 10] or by catalytic dismutation [22] Besidesmedicinal applications fullerenes are also used in DNAphotocleavage enzyme inhibition and antimicrobial activityand as contrast agent or radiotracer [23]The primary advan-tages of transdermal antioxidant using fullerene incorporatednanoemulsions could be of a direct application in protectingthe human skin that is exposed to ultraviolet (UV) radiationPotential skin irritation can be avoided due to the presenceof lower concentration of surfactants as compared to that inmicroemulsions

In this study the physical and structural aspects offullerene nanoemulsions comprised of mixed nonionic sur-factants and palm kernel oil esters which are presented hereDifferent formulations of fullerene stabilized by xanthan gumwere prepared by using combination of high and low energyemulsification techniquesThe physicochemical properties ofthe novel formulations were characterized with an emphasison the thermodynamic and flow behavior

2 Materials and Methods

21 Materials Powdered fullerene (C60) with 995 purity

xanthan gum from Xanthomonas campestris white beeswaxpolyoxyethylene sorbitan monooleate (Tween 80) and sor-bitan monooleate (Span 80) were purchased from Sigma-Aldrich (St Louis USA) The average molecular weight ofxanthan gum was estimated as 152 kDa [24] Palm kernel oilesters (PKOEs) were synthesized in our laboratory throughenzymatic transesterification of palm kernel oil and oleylalcohol using Lipozyme RM IM as the catalyst [25] The fattyacid composition of PKOEs is shown in Table 1 Preservative

Table 1The percentage of fatty acid composition in palm kernel oilesters

Palm kernel oil esterscomposition

(number of carbonatoms number ofdouble bonds)

Percentage ()

Oleyl caproate C24 1 05Oleyl caprate C26 1 56Oleyl caprylate C28 1 59Oleyl laurate C30 1 541Oleyl myristate C32 1 139Oleyl palmitate C34 1 62Oleyl stearate C36 1 12Oleyl oleate C36 2 64Oleyl linoleate C36 3 17

phenonip was obtained from Bramble Berry (BellinghamUSA) Deionized water was purified using Milli-Q watersystem (Billerica USA)

22 Construction of Pseudoternary Phase Diagrams Fulle-renes were assayed at 160 120583gg of PKOEs by stirring usingmagnetic stirrer at 400 rpm for 24 h at room temperature(2980 plusmn 05 K) Mixture of fullerene solution with Tween80 was filled in 11 screw-cap vials at different ratios (ww)of 10 0 9 1 8 2 7 3 6 4 5 5 4 6 3 7 2 8 1 9 and0 10 respectively Deionized water 5 (ww) was addedeach time into the vials containing mixtures All componentswere weighed using analytical balance (Dragon 204 MettlerToledo Spain) and microbalance (CPA2P Sartorius Ger-many) Capwas tightened and homogenized for 20min usinga vortex mixer equipped with flask accessory (VTX-3000LUzusio Japan) Subsequently the samples were centrifuged(Hermle Labor Technik Germany) at 4000 rpm for 15min toobserve any phase separation through cross polarized platesfor visual identification of physical appearances The abovesteps were repeated with consecutive addition of 5 (ww)deionized water

The phase behavior study for mixed surfactant system(Tween 80 Span 80) was conducted The pseudoternaryphase diagram was constructed at room temperature (2980plusmn 05 K) and was plotted using SigmaPlot version 12 by SystatSoftware Inc (San Jose USA) Classification of phase statewas made according to the physical appearance observedwhich was categorized into isotropic homogeneous and twoor multiphase regions

23 Hydrophilic-Lipophilic Balance (HLB) An approachusing HLB concept an empirical parameter was appliedto determine the hydrophilic and hydrophobic content ofsurfactants and was used to study the phase behavior of themixtures This method aims to achieve the required HLBvalue for a given oil to obtain stable emulsion system HighHLB value indicates high hydrophilicity of the surfactantsystem or vice versa The HLB values of mixed binary




100times (HLB

119860minusHLB

119861) +HLB

119861

(1)









120590 = 119870 sdot 120574119899 (2)





PKOEs Flln 0 10 20 30 40 50 60 70 80 90 100

Tween 80

0

10

20

30

40

50

60

70

80

90

1000

10

20

30

40

50

60

70

80

90

100H2O

(a)

PKOEs Flln0 10 20 30 40 50 60 70 80 90 100


0

10

20

30

40

50

60

70

80

90

1000

10

20

30

40

50

60

70

80

90

100H2O

(b)

0 10 20 30 40 50 60 70 80 90 100


0

10

20

30

40

50

60

70

80

90

1000

10

20

30

40

50

60

70

80

90

100

Pre-F tested

H2O PKOEs Flln

(c)

PKOEs Flln0 10 20 30 40 50 60 70 80 90 100


0

10

20

30

40

50

60

70

80

90

1000

10

20

30

40

50

60

70

80

90

100H2O

(d)



















(nm)pH









120578 = 120578119900exp (

119864119886

119877119879) (3)






0

100

200

300

400

500

600

700

800

0 1 2 3 4

Con

duct

ivity

(120583S

cm)

[Beeswax] ( ww)

(a)

000

002

004

006

008

010

012

014

016

0 1 2 3 4[Beeswax] ( ww)

Surfa

ce ch

arge

(10minus6c

m2)

(b)

0

002

004

006

008

01

0 1 2 3 4

Dyn

amic

mob

ility

(120583m

sV

cm

)

[Beeswax] ( ww)

10 (ww)08 (ww)06 (ww)

04 (ww)02 (ww)

Xanthan gum

(c)

10 (ww)08 (ww)06 (ww)

04 (ww)02 (ww)

Xanthan gum

0

2

4

6

8

10

0 1 2 3 4

Deb

ye le

ngth

(nm

)

[Beeswax] ( ww)

(d)





120578 = (119873ℎ

120592) exp(

Δ119867lowast

vis119877119879


vis119877

) (4)






(b) 04 1 3173 0202 0983(c) 06 1 7305 0144 0976(d) 08 1 9438 0137 0988(e) 1 1 1249 0147 099

FNE4(b) 04 2 4318 0217 0981(c) 06 2 8742 0104 098(d) 08 2 1032 0137 0971(e) 1 2 1578 0132 0984

FNE5(b) 04 3 5247 019 0986(c) 06 3 8886 0143 0981(d) 08 3 1102 0141 098(e) 1 3 2132 0095 0974

0

20

40

60

80

100

120

298

303

308

3130204

0608

10

Visc

osity

(Pa s

)

Tempe

ratur

e (K)

[Xanthan gum] ( ww)


or

ln 120578 = [ln(119873ℎ120592) minus

Δ119878lowast

vis119877

] +Δ119867lowast

vis119877119879

(5)


01

1

10

100

1000

01 1 10 100 1000

Appa

rent

visc

osity

(Pa s

)

Shear rate (1s)

10 (ww)08 (ww)

06 (ww)04 (ww)

Xanthan gum



ln 120578 = 119886 + 119887119879 + 1198881198792 (6)


119889 ln 120578119889119879


vis

1198771198792

= 119887 + 2119888119879 (7)











Δ119878lowast



vis)

119879 (8)


Δ119866lowast

vis = 119877119879 ln(120578120592

119873ℎ) (9)









(a) M

(b) M

(c)

(d)

(e)

FNE3(a) M

(b) M

(c)

(d)

(e)

FNE4(a) M

(b) M

(c)

(d)

(e)

FNE5(a) M

(b) M

(c)

(d)

(e)






4 Conclusions




Acknowledgment



References














60as a radical


























2and O

1WO

2



























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials






100times (HLB

119860minusHLB

119861) +HLB

119861

(1)









120590 = 119870 sdot 120574119899 (2)





PKOEs Flln 0 10 20 30 40 50 60 70 80 90 100

Tween 80

0

10

20

30

40

50

60

70

80

90

1000

10

20

30

40

50

60

70

80

90

100H2O

(a)

PKOEs Flln0 10 20 30 40 50 60 70 80 90 100


0

10

20

30

40

50

60

70

80

90

1000

10

20

30

40

50

60

70

80

90

100H2O

(b)

0 10 20 30 40 50 60 70 80 90 100


0

10

20

30

40

50

60

70

80

90

1000

10

20

30

40

50

60

70

80

90

100

Pre-F tested

H2O PKOEs Flln

(c)

PKOEs Flln0 10 20 30 40 50 60 70 80 90 100


0

10

20

30

40

50

60

70

80

90

1000

10

20

30

40

50

60

70

80

90

100H2O

(d)



















(nm)pH









120578 = 120578119900exp (

119864119886

119877119879) (3)






0

100

200

300

400

500

600

700

800

0 1 2 3 4

Con

duct

ivity

(120583S

cm)

[Beeswax] ( ww)

(a)

000

002

004

006

008

010

012

014

016

0 1 2 3 4[Beeswax] ( ww)

Surfa

ce ch

arge

(10minus6c

m2)

(b)

0

002

004

006

008

01

0 1 2 3 4

Dyn

amic

mob

ility

(120583m

sV

cm

)

[Beeswax] ( ww)

10 (ww)08 (ww)06 (ww)

04 (ww)02 (ww)

Xanthan gum

(c)

10 (ww)08 (ww)06 (ww)

04 (ww)02 (ww)

Xanthan gum

0

2

4

6

8

10

0 1 2 3 4

Deb

ye le

ngth

(nm

)

[Beeswax] ( ww)

(d)





120578 = (119873ℎ

120592) exp(

Δ119867lowast

vis119877119879


vis119877

) (4)






(b) 04 1 3173 0202 0983(c) 06 1 7305 0144 0976(d) 08 1 9438 0137 0988(e) 1 1 1249 0147 099

FNE4(b) 04 2 4318 0217 0981(c) 06 2 8742 0104 098(d) 08 2 1032 0137 0971(e) 1 2 1578 0132 0984

FNE5(b) 04 3 5247 019 0986(c) 06 3 8886 0143 0981(d) 08 3 1102 0141 098(e) 1 3 2132 0095 0974

0

20

40

60

80

100

120

298

303

308

3130204

0608

10

Visc

osity

(Pa s

)

Tempe

ratur

e (K)

[Xanthan gum] ( ww)


or

ln 120578 = [ln(119873ℎ120592) minus

Δ119878lowast

vis119877

] +Δ119867lowast

vis119877119879

(5)


01

1

10

100

1000

01 1 10 100 1000

Appa

rent

visc

osity

(Pa s

)

Shear rate (1s)

10 (ww)08 (ww)

06 (ww)04 (ww)

Xanthan gum



ln 120578 = 119886 + 119887119879 + 1198881198792 (6)


119889 ln 120578119889119879


vis

1198771198792

= 119887 + 2119888119879 (7)











Δ119878lowast



vis)

119879 (8)


Δ119866lowast

vis = 119877119879 ln(120578120592

119873ℎ) (9)









(a) M

(b) M

(c)

(d)

(e)

FNE3(a) M

(b) M

(c)

(d)

(e)

FNE4(a) M

(b) M

(c)

(d)

(e)

FNE5(a) M

(b) M

(c)

(d)

(e)






4 Conclusions




Acknowledgment



References














60as a radical


























2and O

1WO

2



























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




PKOEs Flln 0 10 20 30 40 50 60 70 80 90 100

Tween 80

0

10

20

30

40

50

60

70

80

90

1000

10

20

30

40

50

60

70

80

90

100H2O

(a)

PKOEs Flln0 10 20 30 40 50 60 70 80 90 100


0

10

20

30

40

50

60

70

80

90

1000

10

20

30

40

50

60

70

80

90

100H2O

(b)

0 10 20 30 40 50 60 70 80 90 100


0

10

20

30

40

50

60

70

80

90

1000

10

20

30

40

50

60

70

80

90

100

Pre-F tested

H2O PKOEs Flln

(c)

PKOEs Flln0 10 20 30 40 50 60 70 80 90 100


0

10

20

30

40

50

60

70

80

90

1000

10

20

30

40

50

60

70

80

90

100H2O

(d)



















(nm)pH









120578 = 120578119900exp (

119864119886

119877119879) (3)






0

100

200

300

400

500

600

700

800

0 1 2 3 4

Con

duct

ivity

(120583S

cm)

[Beeswax] ( ww)

(a)

000

002

004

006

008

010

012

014

016

0 1 2 3 4[Beeswax] ( ww)

Surfa

ce ch

arge

(10minus6c

m2)

(b)

0

002

004

006

008

01

0 1 2 3 4

Dyn

amic

mob

ility

(120583m

sV

cm

)

[Beeswax] ( ww)

10 (ww)08 (ww)06 (ww)

04 (ww)02 (ww)

Xanthan gum

(c)

10 (ww)08 (ww)06 (ww)

04 (ww)02 (ww)

Xanthan gum

0

2

4

6

8

10

0 1 2 3 4

Deb

ye le

ngth

(nm

)

[Beeswax] ( ww)

(d)





120578 = (119873ℎ

120592) exp(

Δ119867lowast

vis119877119879


vis119877

) (4)






(b) 04 1 3173 0202 0983(c) 06 1 7305 0144 0976(d) 08 1 9438 0137 0988(e) 1 1 1249 0147 099

FNE4(b) 04 2 4318 0217 0981(c) 06 2 8742 0104 098(d) 08 2 1032 0137 0971(e) 1 2 1578 0132 0984

FNE5(b) 04 3 5247 019 0986(c) 06 3 8886 0143 0981(d) 08 3 1102 0141 098(e) 1 3 2132 0095 0974

0

20

40

60

80

100

120

298

303

308

3130204

0608

10

Visc

osity

(Pa s

)

Tempe

ratur

e (K)

[Xanthan gum] ( ww)


or

ln 120578 = [ln(119873ℎ120592) minus

Δ119878lowast

vis119877

] +Δ119867lowast

vis119877119879

(5)


01

1

10

100

1000

01 1 10 100 1000

Appa

rent

visc

osity

(Pa s

)

Shear rate (1s)

10 (ww)08 (ww)

06 (ww)04 (ww)

Xanthan gum



ln 120578 = 119886 + 119887119879 + 1198881198792 (6)


119889 ln 120578119889119879


vis

1198771198792

= 119887 + 2119888119879 (7)











Δ119878lowast



vis)

119879 (8)


Δ119866lowast

vis = 119877119879 ln(120578120592

119873ℎ) (9)









(a) M

(b) M

(c)

(d)

(e)

FNE3(a) M

(b) M

(c)

(d)

(e)

FNE4(a) M

(b) M

(c)

(d)

(e)

FNE5(a) M

(b) M

(c)

(d)

(e)






4 Conclusions




Acknowledgment



References














60as a radical


























2and O

1WO

2



























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials















(nm)pH









120578 = 120578119900exp (

119864119886

119877119879) (3)






0

100

200

300

400

500

600

700

800

0 1 2 3 4

Con

duct

ivity

(120583S

cm)

[Beeswax] ( ww)

(a)

000

002

004

006

008

010

012

014

016

0 1 2 3 4[Beeswax] ( ww)

Surfa

ce ch

arge

(10minus6c

m2)

(b)

0

002

004

006

008

01

0 1 2 3 4

Dyn

amic

mob

ility

(120583m

sV

cm

)

[Beeswax] ( ww)

10 (ww)08 (ww)06 (ww)

04 (ww)02 (ww)

Xanthan gum

(c)

10 (ww)08 (ww)06 (ww)

04 (ww)02 (ww)

Xanthan gum

0

2

4

6

8

10

0 1 2 3 4

Deb

ye le

ngth

(nm

)

[Beeswax] ( ww)

(d)





120578 = (119873ℎ

120592) exp(

Δ119867lowast

vis119877119879


vis119877

) (4)






(b) 04 1 3173 0202 0983(c) 06 1 7305 0144 0976(d) 08 1 9438 0137 0988(e) 1 1 1249 0147 099

FNE4(b) 04 2 4318 0217 0981(c) 06 2 8742 0104 098(d) 08 2 1032 0137 0971(e) 1 2 1578 0132 0984

FNE5(b) 04 3 5247 019 0986(c) 06 3 8886 0143 0981(d) 08 3 1102 0141 098(e) 1 3 2132 0095 0974

0

20

40

60

80

100

120

298

303

308

3130204

0608

10

Visc

osity

(Pa s

)

Tempe

ratur

e (K)

[Xanthan gum] ( ww)


or

ln 120578 = [ln(119873ℎ120592) minus

Δ119878lowast

vis119877

] +Δ119867lowast

vis119877119879

(5)


01

1

10

100

1000

01 1 10 100 1000

Appa

rent

visc

osity

(Pa s

)

Shear rate (1s)

10 (ww)08 (ww)

06 (ww)04 (ww)

Xanthan gum



ln 120578 = 119886 + 119887119879 + 1198881198792 (6)


119889 ln 120578119889119879


vis

1198771198792

= 119887 + 2119888119879 (7)











Δ119878lowast



vis)

119879 (8)


Δ119866lowast

vis = 119877119879 ln(120578120592

119873ℎ) (9)









(a) M

(b) M

(c)

(d)

(e)

FNE3(a) M

(b) M

(c)

(d)

(e)

FNE4(a) M

(b) M

(c)

(d)

(e)

FNE5(a) M

(b) M

(c)

(d)

(e)






4 Conclusions




Acknowledgment



References














60as a radical


























2and O

1WO

2



























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials






(nm)pH









120578 = 120578119900exp (

119864119886

119877119879) (3)






0

100

200

300

400

500

600

700

800

0 1 2 3 4

Con

duct

ivity

(120583S

cm)

[Beeswax] ( ww)

(a)

000

002

004

006

008

010

012

014

016

0 1 2 3 4[Beeswax] ( ww)

Surfa

ce ch

arge

(10minus6c

m2)

(b)

0

002

004

006

008

01

0 1 2 3 4

Dyn

amic

mob

ility

(120583m

sV

cm

)

[Beeswax] ( ww)

10 (ww)08 (ww)06 (ww)

04 (ww)02 (ww)

Xanthan gum

(c)

10 (ww)08 (ww)06 (ww)

04 (ww)02 (ww)

Xanthan gum

0

2

4

6

8

10

0 1 2 3 4

Deb

ye le

ngth

(nm

)

[Beeswax] ( ww)

(d)





120578 = (119873ℎ

120592) exp(

Δ119867lowast

vis119877119879


vis119877

) (4)






(b) 04 1 3173 0202 0983(c) 06 1 7305 0144 0976(d) 08 1 9438 0137 0988(e) 1 1 1249 0147 099

FNE4(b) 04 2 4318 0217 0981(c) 06 2 8742 0104 098(d) 08 2 1032 0137 0971(e) 1 2 1578 0132 0984

FNE5(b) 04 3 5247 019 0986(c) 06 3 8886 0143 0981(d) 08 3 1102 0141 098(e) 1 3 2132 0095 0974

0

20

40

60

80

100

120

298

303

308

3130204

0608

10

Visc

osity

(Pa s

)

Tempe

ratur

e (K)

[Xanthan gum] ( ww)


or

ln 120578 = [ln(119873ℎ120592) minus

Δ119878lowast

vis119877

] +Δ119867lowast

vis119877119879

(5)


01

1

10

100

1000

01 1 10 100 1000

Appa

rent

visc

osity

(Pa s

)

Shear rate (1s)

10 (ww)08 (ww)

06 (ww)04 (ww)

Xanthan gum



ln 120578 = 119886 + 119887119879 + 1198881198792 (6)


119889 ln 120578119889119879


vis

1198771198792

= 119887 + 2119888119879 (7)











Δ119878lowast



vis)

119879 (8)


Δ119866lowast

vis = 119877119879 ln(120578120592

119873ℎ) (9)









(a) M

(b) M

(c)

(d)

(e)

FNE3(a) M

(b) M

(c)

(d)

(e)

FNE4(a) M

(b) M

(c)

(d)

(e)

FNE5(a) M

(b) M

(c)

(d)

(e)






4 Conclusions




Acknowledgment



References














60as a radical


























2and O

1WO

2



























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




0

100

200

300

400

500

600

700

800

0 1 2 3 4

Con

duct

ivity

(120583S

cm)

[Beeswax] ( ww)

(a)

000

002

004

006

008

010

012

014

016

0 1 2 3 4[Beeswax] ( ww)

Surfa

ce ch

arge

(10minus6c

m2)

(b)

0

002

004

006

008

01

0 1 2 3 4

Dyn

amic

mob

ility

(120583m

sV

cm

)

[Beeswax] ( ww)

10 (ww)08 (ww)06 (ww)

04 (ww)02 (ww)

Xanthan gum

(c)

10 (ww)08 (ww)06 (ww)

04 (ww)02 (ww)

Xanthan gum

0

2

4

6

8

10

0 1 2 3 4

Deb

ye le

ngth

(nm

)

[Beeswax] ( ww)

(d)





120578 = (119873ℎ

120592) exp(

Δ119867lowast

vis119877119879


vis119877

) (4)






(b) 04 1 3173 0202 0983(c) 06 1 7305 0144 0976(d) 08 1 9438 0137 0988(e) 1 1 1249 0147 099

FNE4(b) 04 2 4318 0217 0981(c) 06 2 8742 0104 098(d) 08 2 1032 0137 0971(e) 1 2 1578 0132 0984

FNE5(b) 04 3 5247 019 0986(c) 06 3 8886 0143 0981(d) 08 3 1102 0141 098(e) 1 3 2132 0095 0974

0

20

40

60

80

100

120

298

303

308

3130204

0608

10

Visc

osity

(Pa s

)

Tempe

ratur

e (K)

[Xanthan gum] ( ww)


or

ln 120578 = [ln(119873ℎ120592) minus

Δ119878lowast

vis119877

] +Δ119867lowast

vis119877119879

(5)


01

1

10

100

1000

01 1 10 100 1000

Appa

rent

visc

osity

(Pa s

)

Shear rate (1s)

10 (ww)08 (ww)

06 (ww)04 (ww)

Xanthan gum



ln 120578 = 119886 + 119887119879 + 1198881198792 (6)


119889 ln 120578119889119879


vis

1198771198792

= 119887 + 2119888119879 (7)











Δ119878lowast



vis)

119879 (8)


Δ119866lowast

vis = 119877119879 ln(120578120592

119873ℎ) (9)









(a) M

(b) M

(c)

(d)

(e)

FNE3(a) M

(b) M

(c)

(d)

(e)

FNE4(a) M

(b) M

(c)

(d)

(e)

FNE5(a) M

(b) M

(c)

(d)

(e)






4 Conclusions




Acknowledgment



References














60as a radical


























2and O

1WO

2



























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials








(b) 04 1 3173 0202 0983(c) 06 1 7305 0144 0976(d) 08 1 9438 0137 0988(e) 1 1 1249 0147 099

FNE4(b) 04 2 4318 0217 0981(c) 06 2 8742 0104 098(d) 08 2 1032 0137 0971(e) 1 2 1578 0132 0984

FNE5(b) 04 3 5247 019 0986(c) 06 3 8886 0143 0981(d) 08 3 1102 0141 098(e) 1 3 2132 0095 0974

0

20

40

60

80

100

120

298

303

308

3130204

0608

10

Visc

osity

(Pa s

)

Tempe

ratur

e (K)

[Xanthan gum] ( ww)


or

ln 120578 = [ln(119873ℎ120592) minus

Δ119878lowast

vis119877

] +Δ119867lowast

vis119877119879

(5)


01

1

10

100

1000

01 1 10 100 1000

Appa

rent

visc

osity

(Pa s

)

Shear rate (1s)

10 (ww)08 (ww)

06 (ww)04 (ww)

Xanthan gum



ln 120578 = 119886 + 119887119879 + 1198881198792 (6)


119889 ln 120578119889119879


vis

1198771198792

= 119887 + 2119888119879 (7)











Δ119878lowast



vis)

119879 (8)


Δ119866lowast

vis = 119877119879 ln(120578120592

119873ℎ) (9)









(a) M

(b) M

(c)

(d)

(e)

FNE3(a) M

(b) M

(c)

(d)

(e)

FNE4(a) M

(b) M

(c)

(d)

(e)

FNE5(a) M

(b) M

(c)

(d)

(e)






4 Conclusions




Acknowledgment



References














60as a radical


























2and O

1WO

2



























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials













Δ119878lowast



vis)

119879 (8)


Δ119866lowast

vis = 119877119879 ln(120578120592

119873ℎ) (9)









(a) M

(b) M

(c)

(d)

(e)

FNE3(a) M

(b) M

(c)

(d)

(e)

FNE4(a) M

(b) M

(c)

(d)

(e)

FNE5(a) M

(b) M

(c)

(d)

(e)






4 Conclusions




Acknowledgment



References














60as a radical


























2and O

1WO

2



























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials








(a) M

(b) M

(c)

(d)

(e)

FNE3(a) M

(b) M

(c)

(d)

(e)

FNE4(a) M

(b) M

(c)

(d)

(e)

FNE5(a) M

(b) M

(c)

(d)

(e)






4 Conclusions




Acknowledgment



References














60as a radical


























2and O

1WO

2



























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




References














60as a radical


























2and O

1WO

2



























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials



























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials










CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials



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Research Article Physicochemical Characterization and ...downloads.hindawi.com/journals/tswj/2014/219035.pdf · Research Article Physicochemical Characterization and Thermodynamic