research article biocompatible bacterial cellulose-poly(2

Hindawi Publishing CorporationBioMed Research InternationalVolume 2013 Article ID 698141 14 pageshttpdxdoiorg1011552013698141

Research ArticleBiocompatible Bacterial Cellulose-Poly(2-hydroxyethylmethacrylate) Nanocomposite Films

Andrea G P R Figueiredo1 Ana R P Figueiredo1 Ana Alonso-Varona2

Susana C M Fernandes13 Teodoro Palomares2 Eva Rubio-Azpeitia2

Ana Barros-Timmons1 Armando J D Silvestre1 Carlos Pascoal Neto1

and Carmen S R Freire1

1 Department of Chemistry and CICECO Campus de Santiago University of Aveiro 3810-193 Aveiro Portugal2 Department of Cellular Biology and Histology Faculty of Medicine and Odontology University of the Basque Country (UPVEHU)Barrio Sarriena sn 48940 Leioa Spain

3 ldquoMaterials + Technologiesrdquo Group Department of Chemical and Environmental Engineering Polytechnic School University of theBasque Country (UPVEHU) Plaza Europa 1 20018 San Sebastian Spain

Correspondence should be addressed to Carmen S R Freire cfreireuapt

Received 30 April 2013 Accepted 15 July 2013

Academic Editor Dong-Wook Han

Copyright copy 2013 Andrea G P R Figueiredo et al This is an open access article distributed under the Creative CommonsAttribution License which permits unrestricted use distribution and reproduction in any medium provided the original work isproperly cited

A series of bacterial cellulose-poly(2-hydroxyethyl methacrylate) nanocomposite films was prepared by in situ radical polymer-ization of 2-hydroxyethyl methacrylate (HEMA) using variable amounts of poly(ethylene glycol) diacrylate (PEGDA) as cross-linkerThin filmswere obtained and their physical chemical thermal andmechanical properties were evaluatedThe films showedimproved translucency compared to BC and enhanced thermal stability and mechanical performance when compared to poly(2-hydroxyethyl methacrylate) (PHEMA) Finally BCPHEMA nanocomposites proved to be nontoxic to human adipose-derivedmesenchymal stem cells (ADSCs) and thus are pointed as potential dry dressings for biomedical applications

1 Introduction

Cellulose the most abundant natural polymer possessesunique properties and advantages [1ndash4] which have beenwidely explored for centuries especially for paper makingand for textile materials More recently cellulose fibres havealso gained considerable and increasing attention as rein-forcing elements in polymeric (nano)composite materials[1 5ndash7] Bacterial cellulose (BC) is a unique form of cellu-lose produced by several bacteria of the Gluconacetobacterand Sarcina genus among others [8 9] Because of itsinherent biocompatibility and unique properties that arisefrom the tridimensional network of nano- and microfibrilsbacterial cellulose is becoming a promising biopolymer forseveral biomedical [6 10ndash16] (eg wound dressing artificial

skin and scaffolds for tissue engineering and soft tissuereplacement) and technological [17ndash21] applications (egoptical transparent nanocomposites electronic paper andfuel cell membranes) BCpolymer nanocomposites havebeen prepared by simple blending of BC nanofibrils with sev-eral polymeric matrices [22ndash27] or by in situ polymerizationof monomers within the cellulose network [16 28ndash32] Thelatter approach is particularly straightforward because theproperties of the nanocomposites can be easily tailored byadjusting the ratio of monomerBC the type and functional-ities of the monomers degree of cross-linking and so forthA limited number of monomers with acrylicmethacrylicmoieties such as glycerol monomethacrylate (GMMA) [16]2-hydroxyethyl methacrylate (HEMA) [16 31] 2-ethoxyethylmethacrylate (EOEMA) [16] acrylamide [28 30] acrylic acid

2 BioMed Research International

(HEMA)

O

O

O O

O

O

O O OO

O O

OOO O

O

O

OH

OHOH

OH(PEGDA)

KPS in water70∘C 6 h

HO

(PHEMAPEGDA)

+ mn

o

m

p q

Figure 1 Schematic representation of HEMA polymerization in the presence of PEGDA to yield PHEMA cross-linked with PEGDA

[29 31 32] and 2-ethylhexyl acrylate [31] have already beenexplored in this context in particular for the development ofBCbased hydrogels

Poly(2-hydroxyethyl methacrylate) (PHEMA) is a versa-tile synthetic polymer with properties suited to a range ofapplications in particular biomedical applications includingsoft contact lenses [33] artificial corneas [34] degradablescaffolds for tissue engineering [35] and drug deliverysystems [36] BCPHEMA hydrogels have already beendescribed as part of two studies dealing with the preparationof BC based hydrogels by in situ polymerization of severalacrylic monomers In both cases the authors focus essentiallyon the swelling behaviour morphology and mechanicalproperties of the hydrogels Other important propertiessuch as thermal stability transparency crystallinity andbiocompatibility as well as their preparation in other formssuch as films or aerogels were not investigated and are alsoimportant for several applications

In the present study BCPHEMA nanocomposites in theform of thin films were prepared by in situ radical polymer-ization in the presence of poly(ethylene glycol) diacrylate(PEGDA) as cross-linker (Figure 1) The effect of the contentof monomer and cross-linker was evaluated The ensuingnanocomposites were characterized in terms of chemicalstructure crystallinity transparency morphology thermalstability mechanical properties and biocompatibility

2 Materials and Methods

21 Chemicals and Materials 2-Hydroxyethyl methacrylate((HEMA) 97 stabilized) and poly(ethylene glycol) diacry-late ((PEGDA) average Mn 258 stabilized) were purchasedfrom Sigma-Aldrich and used as received Potassium persul-fate ((KPS) 98 Panreac) was used as thermal initiator Allother reagents and solvents were of analytical grade and usedas received

Bacterial cellulose (BC) (tridimensional network of nano-and microfibrils with 10ndash200 nm width) in the form ofwet membranes was produced in our laboratory using theGluconacetobacter sacchari bacterial strain [8] and followingestablished procedures [37]

22 BCPHEMANanocomposites Preparation WetBCmem-branes (sim100mg dry weigh 4 times 4 cm2 and 08 cm thickness)were weighted and 60 of their water content was removedwith absorbent paper Drained BC membranes were put inErlenmeyers stoppedwith rubber septa and then purged withnitrogen At the same time aqueous solutions (5mL) withdifferent amounts ofmonomerHEMA (75 150 300mg) 12of KPS inititaor (ww relative to monomer) and PEGDA (01 and 5 (wcross-linkerwmonomer)) were prepared (Table 1) andalso purged with nitrogen (in an ice bath) for 30min Thenthe solutions were transferred with a syringe to the Erlen-meyers containing the drained BCmembranes After that themembranes were left to stand for 1 hour at room temperature(25∘C) until the complete absorptionincorporation of thesolutions Subsequently the reaction mixtures were left at70∘C (to induce in situ radical polymerization) for 6 hThenthe septum was pulled off and the BC membranes washedwith water (100mL) during 30min This washing procedurewas repeated three times The washed membranes wereplaced over Petri dishes and dried at 40∘C in a ventilated ovenfor 5ndash12 h The dried membranes were kept in a desiccatoruntil their use All experiments were made in triplicate andanalysed in the form of thin nanocomposite films Samplesof PHEMA and PHEMA cross-linked with PEGDA wereprepared under the same conditions in the absence of BC forcomparative purposes

Three samples from each series were freeze-dried andweighed PHEMAPEGDA and BC percent composition ofthe nanocomposites (Table 1) were estimated by difference tothe original BC weight

BioMed Research International 3

Table 1 Identification of the nanocomposite films and component contents estimation

BCPHEMAPEGDAnanocomposites Dry BC (mg) HEMA (mg) PEGDA () PHEMA () BC ()

BCPHEMAPEGDA(1 3 0)

100 300

0 740 260

BCPHEMAPEGDA(1 3 001) 1 739 261

BCPHEMAPEGDA(1 3 005) 5 759 241

BCPHEMAPEGDA(1 15 0)

100 150

0 570 430

BCPHEMAPEGDA(1 15 001) 1 592 408

BCPHEMAPEGDA(1 15 005) 5 610 390


100 75

0 361 639

BCPHEMAPEGDA(1 075 001) 1 403 597

BCPHEMAPEGDA(1 075 005) 5 448 552

23 Nanocomposite Films Characterization All ensuingfilms were characterized in terms of structure (FTIRand 13C NMR) morphology (SEM) crystallinity (XRD)transparencyopacity (visible light) thermal stability anddegradation profile (TGA) thermodynamical properties(DMA) swelling behaviour and biocompatibility

FTIR spectra were taken with a Perkin-Elmer FT-IRSystem Spectrum BX spectrophotometer equipped with asingle horizontal Golden Gate ATR cell over the range 600ndash4000 cmminus1 at a resolution of 4 cmminus1 averaged over 32 scans

CPMAS 13C NMR spectra were recorded on a BrukerAvance III 400 spectrometer operating at a B0 field of 94 Tusing 9 kHz MAS with proton 90∘ pulse of 3 120583s CPMAS 13CNMR spectra were acquired using a contact time of 2000msand a time between scans of 3 s 13C chemical shifts werereferenced with respect to glycine (C=O at 17603 ppm)

SEM micrographs of the nanocomposite film surfaceswere obtained on an HR-FESEM SU-70 Hitachi equipmentoperating at 15 kV and that of BC was taken with a HitachiS4100 equipment operating in the field emission modeSamples were deposited on a steel plate and coated withcarbon

The X-ray diffraction (XRD) measurements were carriedout with a Phillips Xrsquopert MPD diffractometer using Cu K120572radiation

The transmittance spectra of the nanocomposite filmswere collected with a UV-vis Spectrophotometer (Perkin-Elmer UV 850) equipped with a 15 cm diameter integratingsphere bearing the holder in the horizontal position Spectrawere recorded at room temperature in steps of 1 nm in therange 400ndash700 nm

TGA essays were carried out using a Shimadzu TGA 50analyser equipped with a platinum cell Samples were heated

at a constant rate of 10∘Cmin from room temperature to800∘C under a nitrogen flow of 20mLmin The thermaldecomposition temperature was taken as the onset of signifi-cant (sim05) weight loss after the initial moisture loss

Dynamic mechanical analyses (DMA) were performedon a Tritec 2000DMA (Triton Technologies) using tensionas deformation mode (single strain) For the temperaturesweeps a ramp rate of 2∘Cmin was used and sampleswere heated from minus100 to 200∘C at a frequency of 1 and10Hz with a displacement of 0005mm Samplesrsquo averagedimensions of the films were approximately 5 times 5 times 02mmTg values were determined using the maximum of the tan 120575curve Films used for DMA tests were kept in a conditioningcabinet at 50 relative humidity (RH) and 30∘C to ensure thestabilization of their water content PHEMA polymers (alsopreviously conditioned) were analysed using the materialpocket accessory in deformation mode

The swelling ratio (SR) of the nanocomposite filmswas measured using the weighing method [5] Specimens(dimensions 1 times 1 cm) were immersed in distilled water atroom temperature to study their swelling in a minimum ofthree samples (tested for each material) The weight increasewas periodically assessed for 2 days Samples were taken outof thewater theirwet surfaceswere immediatelywiped dry infilter paper and then reimmersedThen the SR was calculatedusing equation (1)

SR () =(119882

119904minus119882

119889)

119882

119889

times 100 (1)

where119882119889is the initial weight of dry film and119882

119904is the weight

of the film swollen in water


BC

BCPHEMAPEGDA

1 3 0 1 3 001 1 3 005

(a)

BCPHEMAPEGDA (1 15 001)BCPHEMAPEGDA(1 15 0)BCPHEMAPEGDA(1 075 001)BCPHEMAPEGDA(1 075 0)BC

0

20

40

60

400 500 600 700

Tran

smitt

ance

()

Wavelength (nm)

BCPHEMAPEGDA

BCPHEMAPEGDA

BCPHEMAPEGDA

BCPHEMAPEGDA

BCPHEMAPEGDA

(1 3 005)

(1 15 005)

(1 3 001)

(1 3 0)

(1 075 005)

(b)

Figure 2 (a) Visual aspect and (b) transmittance of the different nanocomposite films

24 In Vitro Cell Response Adipose-derived stem cells(ADSCs) were used in a short-term standard cytotoxicityassay of BC and BCPHEMAPEGDA (1 3 005)membranes The procedure and methods are describedelsewhere [38] Briefly membranes (6 cm2 of area le05mmthick) were sterilized with 70 ethanol for 2 h at roomtemperature and rinsed with phosphate buffered saline(PBS) aqueous solutions for 1 h To prepare extracts of testmaterials according to the international standard ISO 10993-12 sterilized samples were incubated in ADSCs growthmedium consisting in Dulbeccorsquos modified Eaglersquos medium((DMEM) Sigma Chemicals Co USA) supplementedwith Glutamax (Sigma) and 10 fetal bovine serum ((FBS)Gibco) at 37∘C for 24 h The ratio of material surfaceextractfluid was constant and equal to 6 cm2mL

For in vitro cytotoxicity assays ADSCs were seeded andallowed to grow for 24 h in 96-well microplates at a densityof 4 times 103 cellswell in the presence of standard culturemedium Then cultures were treated for 24 48 and 72 hwith the previously prepared extracted media In additionhigh-density polyethylene (negative control USP RockvilleUSA) and poly(vinyl chloride) (positive control PortexUK) were used The metabolic activity of viable cells wasdetermined by a colorimetric assay (Cell Proliferation Kit IMTT Roche) Briefly only viable cells could reduce MTTto formazan pigment which is then dissolved in dimethyl-sulfoxide (DMSO) The cell number per well is proportionalto the recorded absorbance of formazan at 550 nm usingan ELISA microplate reader All assays were conducted in

triplicate and each experiment was repeated three timesMean values and their standard deviations were calculated

To analyze ADSCs seeding and proliferation ontothe films scanning electron microscopy (SEM) studieswere carried out on cultured human ADSCs on BC andBCPHEMAPEGDA (1 3 005) membranes Aliquots con-taining 5 times 104 cells were seeded under static conditionsonto BC and BCPHEMAPEGDA (1 3 005) membranesin ultralow attachment 24-well culture plates (Costar) pre-wetted with standard culture medium The cultures wereincubated for 72 h to allow attachment and proliferation(37∘C 5 CO

2 and 95 RH) Subsequently samples were

rinsed with PBS to remove nonattached cells fixed with 2glutaraldehyde in a cacodylate buffer (01M pH = 74) andpostfixed using OsO

4for 1 h washed in phosphate buffer

solution and dehydrated using series of graded ethanol solu-tions Samples were dried through CO

2critical point gold

sputtered and analyzed in a SA-3400N Hitachi microscopeThe voltage used was 150 kV and magnifications selected forSEM images range from 1 500 to 10 000x

3 Results and Discussion

A series of BCPHEMA nanocomposite films was preparedby varying the amounts of monomer (HEMA) and cross-linker (PEGDA) impregnated into the BC membranes priorto the polymerization step (Table 1) All obtained nanocom-posite films were very homogeneous (Figure 2(a)) and con-siderably more translucent than the pristine BC membrane


HEMA

600110016002100260031003600

BC

OHCH2

CH

CH

C-O(-C-O-C)

C-O(-C-O-H)

120575s HOH

Wavenumber (cmminus1)

C = O

120575 C-OH

PHEMAPEGDA (1 001)

BCPHEMAPEGDA (1 3 001)



Figure 3 FTIR spectra of BC HEMA PHEMAPEGDA (1 001) and BCPHEMA nanocomposite films (1 3)

The amount of polymer imbibed in BC was shown tosystematically grow with the amount of HEMA added as wellas with the amount of cross-linker (PEGDA) In this last casecross-linking will prevent PHEMA to be drained from BCnetwork duringwashing or afterwards during any applicationof the material

Figure 2(b) shows the light transmittance of all BCPHEMA nanocomposite films in the range of 400ndash700 nmThe incorporation of PHEMA polymeric chains into the BCnanofibrils network increases considerably the transmittanceof the films because of the inherent high transparency of thispolymer [39] and of its excellent compatibility with the BCnanofibrils The translucency increases with the amount ofmonomer and for the same monomer content increases alsowith the cross-linker content confirming the expected higher

retention of PHEMA inside the BC network promoted by thecross-linking of the polymeric chains

31 Structural Characterization The success of the polymer-ization reaction inside BC membranes was confirmed byFTIR and NMR analyses

Figure 3 shows the FTIR spectra of BC HEMA andPHEMA (prepared in the same conditions but withoutcellulose and cross-linker) and of BCPHEMA nanocompos-ites with higher content of PHEMA as an example (seriesBCPHEMAPEGDA(1 3)) All BCPHEMAfilms producedby this methodology present as expected an FTIR spectraltrace correspondent to the sum of both components (BC andPHEMA)The success of the polymerization of HEMA insidethe BC membranes was confirmed by the appearance in the


OO

OO

OH

OH

OHHO 1

23

4 5

6

BC

C = O

C = O

C-1

C-4C-1

C-4

C-2 3 5

C-2 3 5

CH2OHC-6

C-6

OCH2

CH2OH

OCH2

Main chainCH2

Main chainCH2

CH3

CH3

050100150200120575 (ppm)

Clowast

Clowast

Clowast

m

n

PHEMAPEGDA (1 0)





Figure 4 CPMAS 13CNMR spectra of nanocomposite films BCPHEMAPEGDA (1 3 0) (1 15 0) and (1 075 0) BCPHEMAPEGDA(1 075 001) and of PHEMAPEGDA (1 0) and BC

films of an intense band at around 1716 cmminus1 attributed to thecarbonyl ester group stretching vibrations in the polymer andto the concomitant disappearance of the band at 1634 cmminus1and of the sharp peak at 814 cmminus1 assigned respectively tothe C=C stretching vibration and to CndashH out-of-the-plane

bending vibration from the vinyl group of the monomerThe bands at 1447 and 747 cmminus1 associated with the bendingvibration mode of CH

2and CH

2rocking characteristic of

methacrylic polymers are also a confirmation of the success-ful formation of PHEMA inside the BC network Finally


(a)

(b)

Figure 5 SEM micrographs of BCPHEMAPEGDA (1 3 0) (left) and BCPHEMAPEGDA (1 3 005) (right) nanocomposite filmsrecorded from surfaces (a) and cross-sections (b)

the vibrations at 3350 cmminus1 (OndashH stretching) 2930 cmminus1 (CndashH stretching) and 1245 cmminus1 (stretching of CndashO) are typicalof both BC and PHEMA Moreover the comparison of thenormalized FTIR spectra of the BCPHEMAPEGDA (1 3)

nanocomposite series clearly confirmed that the amount ofPHEMA retained inside the BC network increased with thecross-linker content based on the increment of the intensityof the characteristic bands of PHEMA namely the carbonyl


10 20 30 402120579 (∘)

PHEMAPEGDA

PHEMAPEGDA

BC

(1 0)

(1 005)

(a)

BCPHEMAPEGDA

BCPHEMAPEGDA

BCPHEMAPEGDA

2120579 (∘)10 20 30 40

(1 3 0)

(1 3 001)

(1 3 005)

(b)

BCPHEMAPEGDA

BCPHEMAPEGDA

BCPHEMAPEGDA

2120579 (∘)10 20 30 40

(1 15 0)

(1 15 001)

(1 15 005)

(c)

BCPHEMAPEGDA

BCPHEMAPEGDA

BCPHEMAPEGDA

2120579 (∘)10 20 30 40

(1 075 0)

(1 075 001)

(1 075 005)

(d)

Figure 6 X-ray diffractograms of the nanocomposite films polymers (with and without cross-linker) and BC

ester stretching vibrations at around 1715 cmminus1This tendencywas also observed for the other series (BCPHEMAPEGDA(1 15) and BCPHEMAPEGDA (1 075)) and is in closeagreement with the transmittance results described above

Figure 4 displays the solid state CPMAS 13CNMR spectraof selected BCPHEMA nanocomposite films namelyBCPHEMAPEGDA (1 3 0) BCPHEMAPEGDA(1 15 0) BCPHEMAPEGDA (1 075 0) and BCPHEMAPEGDA (1 075 001) as well as of startingcomponents BC and PHEMA It is evident that the 13CNMR spectra of the BCPHEMA nanocomposites are alsoa sum of the resonances typical of BC carbons at 120575 652(C-6) 714ndash743 (C-235) 900 (C-4) and 1048 ppm (C-1)and of PHEMA at 162-232 (120572-CH

3) 450 (quaternary C)

554 (CH2main chain) 601 (ndashOndashCH

2) 672 (HOndashCH

2ndash)

and finally 1782 ppm assigned to C=O Carbon resonancesspecific of PEGDA are not visible due to the low content ofthis last component The intensity of the PHEMA carbonresonances compared to those of BC increases with theproportion of monomer and cross-linker (data not shown)used in each experiment reflecting different polymercontents which is in good agreement with the FTIR analysisand the weight gains reported above (Table 1)

The absence of FTIR vibrations or 13C resonances typicalof the monomer (or of other contaminants) in the FTIRand NMR spectra of the nanocomposites demonstrates thecomplete consumptionremoval of all reactantsbyproductsduring the polymerization and washing steps which isa crucial aspect when considering biomedical applica-tions


0

50

100

150

200

250

300

010 20 30 40 50

Swel

ling

ratio

()

Time (h)

BCBCPHEMAPEGDA (1 3 001)BCPHEMAPEGDA (1 3 005)BCPHEMAPEGDA (1 3 0)BCPHEMAPEGDA (1 15 0)BCPHEMAPEGDA (1 15 001)BCPHEMAPEGDA (1 15 005)BCPHEMAPEGDA (1 075 0)BCPHEMAPEGDA (1 075 001)BCPHEMAPEGDA (1 075 005)

(a)

0

50

100

150

200

250

1 2 3 4 5 6 70

Swel

ling

ratio

()

Time (h)


(b)

Figure 7 (a) Plot of the swelling ratio as a function of time of all BCPHEMAnanocomposite films andBCmembrane (0ndash48 h) (b) Expansion0ndash7 h

32MorphologyCharacterization Aselection of SEMmicro-graphs of the surface of BCPHEMA (1 3) nanocompositeswith 0 and 5 of cross-linker is shown in Figure 5(a)

The characteristic tridimensional nanofibrillar networkof BC [24 38] was clearly observed in the surface of allnanocomposite films indicating that this was not affectedby the polymerization reaction In addition the cellulosenanofibrils are perfectly embedded within the PHEMAmatrix The nanocomposites without cross-linker displayeda less homogenous morphology with several unfilled partssuggesting a considerable superficial lixiviation of PHEMAduring the washing step

For the same nanocomposite films a selection of SEMmicrographs of the fractured zones (cross-section) is shownin Figure 5(b) For each sample two different magnificationswere used in order to display the distribution of PHEMAin the BC network and the interfacial adhesion betweenthe two composite components The cross-section micro-graphs of both nanocomposite films displayed the typicallamellar morphology of BC completely impregnated withPHEMA These images also provided evidence of the stronginterfacial adhesion between BC nanofibrils and PHEMAas shown by the nanofibers breakage during fracturing andthe homogeneous dispersion of the matrix within the BC

network This behaviour is obviously due to the excellentcompatibility between BC and PHEMA that arises fromthe potential establishment of hydrogen bonds betweenthem These results clearly support the superior mechanicalproperties of the BCPHEMA nanocomposites as suggestedby the mechanical tests discussed below

33 X-Ray Diffraction Characterization X-ray diffractionanalyses have been performed on neat BC membranesPHEMA matrices (with different amounts of cross-linker)and all BCPHEMA nanocomposite films (Figure 6)

As it is well known BC exhibits a diffractogram typicalof Cellulose I (native cellulose) with the main diffractionpeaks at 2120579 143 159 226 and 337∘ [40] while all PHEMAmatrices are characterized by a broad peak centred at around2120579 18∘ typical of fully amorphous materials The X-raydiffraction profiles of the BCPHEMA nanocomposite filmsonly showed that the typical diffraction peaks of BC andtheir magnitude increases as expected with the BC contentFor the nanocomposite films with lower cross-linker contentthese peaks are quite evident In fact the diffractogramsof these materials look very closely to that of BC Theincrease on crystallinity observed for the nanocompositefilms together with the unique BC morphology is closely


0

20

40

60

80

100

0 100 200 300 400 500 600 700 800

0 200 400 600 800Mas

s los

s (

)

Temperature (∘C)

BCPHEMAPEGDA (1 0)PHEMAPEGDA (1 005)

(a)

0

20

40

60

80

100

0 100 200 300 400 500 600 700 800

Mas

s los

s (

)

Temperature (∘C)

0 200 400 600 800

BC


BCPHEMAPEGDA (1 3 001)BCPHEMAPEGDA (1 3 005)

(b)

Figure 8 (a) TGA thermograms of BC and PHEMAPEGDA (1 0) and PHEMAPEGDA (1 005) (b) TGA thermograms of BCPHEMAPEGDA (1 3 0) BCPHEMAPEGDA (1 3 001) and BCPHEMAPEGDA (1 3 005)

related to the improvement of the mechanical performanceof the PHEMABC based films discussed later

34 Swelling Behaviour Swelling studies were performed inorder to evaluate the rehydration ability of the nanocom-posite films by their immersion in water during at least48 h (reverse swelling after drying) Swelling ratios of thenative BC membrane (for comparison) and BCPHEMAnanocomposite films are presented in Figure 7(a) (0ndash48 h)and Figure 7(b) (expansion 0ndash7 h) All samples absorbedwater during the experiment following similar patternsAfter a relatively fast water uptake during the first hour thewater absorption slowed down leading gradually to a plateauafter 24 hours However the BCPHEMA nanocompositefilms showed a considerably higher swelling ratio than BCmembranes specifically 200ndash270 and 100 respectivelyThis behaviour is attributed to the presence of the hydrophilicPHEMA polymeric chains within the nanostructured BCnetwork which additionally prevents the collapse of BCnanostructure during drying

The PHEMA content in the nanocomposites that is theamount of PHEMA retained in the BC network is strictlyrelated to the improvement on their swelling ratio beingin general higher for those with cross-linker which is inclose agreement with the NMR and FTIR analyses Thesenanocomposites increase the water retention capacity of BCin its film form originating improved BC nanocompositefilms suitable for several biomedical applications such aswound healing and topical drug delivery

35 Thermal Properties Thermogravimetric analysis ofBCPHEMA nanocomposite films was carried out toevaluate their thermal stability and degradation profile(Table 2 Figure 8) The thermal stability is a quite importantaspect in several applications where materials might besubmitted to high temperatures such as sterilization in thecase of biomedical materials Reference BC membrane and

Table 2Thermal degradation profiles of the studied nanocompositefilms

BCPHEMAnanocomposites

massloss at100∘C

Tdi(∘C)

Tdmax1(∘C)

Tdmax2(∘C)

BCPHEMAPEGDA(1 3 0) 336 272 384 434

BCPHEMAPEGDA(1 3 001) 179 274 388 442

BCPHEMAPEGDA(1 3 005) 179 250 373 434

BCPHEMAPEGDA(1 15 0) 295 276 395 443

BCPHEMAPEGDA(1 15 001) 225 266 387 440

BCPHEMAPEGDA(1 15 005) 281 257 373 430

BCPHEMAPEGDA(1 075 0) 303 276 389 442

BCPHEMAPEGDA(1 075 001) 206 272 390 441

BCPHEMAPEGDA(1 075 005) 244 235 386 433

PHEMA matrices (with and without cross-linker) were alsoanalysed for comparison purposes (Figure 8)

BC showed a single weight-loss feature typical of cellu-losic substrates with initial and maximum decompositiontemperatures at around 260 and 350∘C respectively [41] Themass loss at around 100∘C is associated with the volatilizationof residual water PHEMA matrices are considerably lessstable than BC since they start to decompose at around200∘C and presented a degradation profile with three maindegradation steps at about 230 290 and 400∘C (Figure 8)[42] The cross-linking of PHEMA with small amounts of


minus110 minus60 minus10 40 90 140 190Temperature (∘C)

BC

(Pa)

998400

14E + 09

14E + 10

Mod

ulus

E

BCPHEMAPEGDA (1 3 0)BCPHEMAPEGDA (1 3 001)BCPHEMAPEGDA (1 3 005)BCPHEMAPEGDA (1 15 0)BCPHEMAPEGDA (1 15 001)BCPHEMAPEGDA (1 15 005)BCPHEMAPEGDA (1 075 0)BCPHEMAPEGDA (1 075 001)BCPHEMAPEGDA (1 075 005)

Figure 9 Storage moduli versus temperature of BC and allnanocomposite films DMA analyses were carried out in tensionmode (1Hz) All the samples were conditioned at 50 RH

PEGDA (up to 5) had no measurable effect on the thermalstability of the polymer

The TGA tracing of BCPHEMA nanocomposite filmsis not a sum of those of the individual components sincethey showed in general a two-step weight-loss degradationprofile with maximum degradation temperatures at 370ndash390and 430ndash440∘C (Table 2 Figure 8) The distinct degradationprofiles and the considerable increments on the Ti andTdmax of the nanocomposites when compared with BC andPHEMA clearly suggest a strong interaction between themand thus excellent compatibility as previously observed bySEM This is probably associated with the establishment ofstrong interactions (hydrogen bonds) between BCnanofibrilsand PHEMA chains The range of PHEMA percentage in thenanocomposites studied here hardly had any effect on thethermal stability and degradation profile of the films

36 DynamicMechanical Properties Figure 9 shows the vari-ation of the storage tensile modulus of BC and BCPHEMAnanocomposite films as a function of temperature Specifi-cally the effect of the amount of PHEMA (and BC) and cross-linker on the viscoelastic properties of the nanocompositeswas assessed

For neat BC membranes the variation of 1198641015840 as a functionof temperature only showed a minor transition at around40∘C attributed to the release of residual water moleculeswhich are known to act as plasticizersThis transitionwas also

24 48 72000102030405060708091011

Positive control

BC

Time (h)

Fold

of n

egat

ive c

ontro

l

lowastlowast lowast

lowastlowastlowastlowastlowastlowast

lowastlowastlowast


Figure 10 ADSCs proliferation in contact with BC BCPHEMAPEGDA (1 3 005) membranes and positive and negative controlduring 24 48 and 72 h Data are presented as mean plusmn standarddeviation of three independent experiments (lowast119875 lt 005)

observed in all BCPHEMA nanocomposites since PHEMAis also considerably hydrophilic For the nanocompositefilms with higher PHEMA contents (Table 1) an additionaltransition was registered in the range 100ndash160∘C with amaximum decrease at around 125∘C This drastic drop ofthe tensile storage modulus 1198641015840 is typical of a relaxationphenomenon associated with the glass-rubber transition ofthe PHEMAmatrix [43] as further confirmed by the analysisof neat PHEMA

As expected all nanocomposites showed lower storagemoduli than that of neat BC because PHEMA matrices areamorphous and thus less rigid than the BCmembrane whichis a highly crystalline material These results clearly indicatethat a set of BCPHEMA nanocomposite films with distinctmechanical performances (but similar thermal stabilities)can be easily designed by simply varying the BCPHEMApercentage contents as well as the percentage of cross-linker Thus this strategy consists in a simple approach toobtain PHEMA based nanocomposite films for applicationsrequiring diverse mechanical performances

37 Biocompatibility The effect of the introduction ofPHEMA polymeric chains into the BC membrane networkon the viability proliferation and cell adhesion of humanADSCs was studied A wide variety of cell lines have beenrecently used to determine cytotoxicity and biocompatibilityof novel materials based on BC including ADSCs [44] Thistype of cells has emerged as an important tool for tissueengineering because they exhibit capacity to differentiateinto mesodermal cell lineages largely to bone cartilage andadipocytes [45 46]

Figure 10 shows the cell viability based on the cell growthratio between extracted fluid from samples and negative con-trol As expected standard growth values were obtained with


BC


Figure 11 SEM images showing morphology of ADSCs at 72 h after seeding on the surface of BC and BCPHEMAPEGDA (1 3 005)membranes

the negative control (high-density polyethylene (HDPE)) anda dramatic reduction of cell number was found with thepositive control (poly(vinyl chloride) (PVC)) Regarding cellscultured with extracted media obtained as described previ-ously with BC and BCPHEMAPEGDA (1 3 005) mem-branes no significant differences in proliferation rates wereobserved among them when we compare with negative con-trol whereas no significant differences exist in growth rate ofcells cultured with BC extracted media a slightly significantlower growth rate was found in the case of cells cultured inBCPHEMAPEGDA (1 3 005) extractedmedia (119875 lt 005)However considering that viability and proliferation ratesabove 70 of the control specifically 91 in BC and 83 inBCPHEMAPEGDA (1 3 005) membranes were observedhere and that according to EN ISO 10993-5200960 amaterialis considered cytotoxic if cell viability is reduced by morethan 30 we can state that BC and BCPHEMAPEGDA(1 3 005) are not cytotoxic for ADSCs

With respect to the ADSC seeding assessment SEM anal-ysis was conducted in order to determine cell morphologyspreading and adhesion onto BC and BCPHEMAPEGDA(1 3 005) membranes Figure 11 shows the micrographs ofADSCs taken after 72 h of seeding on these membranes Inbothmembranes ADSCswerewell spread adhered correctlyand proliferated to form a continuous layer of cells fullycovering the membranes

As shown in lowmagnification photomicrograph (1500x)ADSCs displayed a spindly morphology with numerouscytoplasmic projections firmly attached to material sur-faces In the enlarged images (10000x) the thin cytoplasmic

projections adhere actively to the porous network and naturalnanofibers structure of the materials In fact these nanos-tructured membranes seem to be ideal for harboring cellgrowth

4 Conclusions

In the present work a systematic study for the productionof BCPHEMA nanocomposite films was performed viain situ radical polymerization of HEMA using PEGDA ascross-linker tailoring its properties by the simple rangingof the polymer andor cross-link content in relation toBC content while the BC nanostructure was retained Theobtained nanocomposite films were fully characterized interms of composition transparency crystallinity morphol-ogy swelling thermal and mechanical properties cytotoxic-ity and biocompatibility

These films are translucent and are considerably morethermally stable than PHEMA matrix These compositesare less rigid materials when compared to BC which isconfirmed by a decrease in the storage tensile modulus andpresent good swelling ratios (sim200ndash260) Biocompatibilitystudies demonstrated that BCPHEMA nanocomposite filmsare noncytotoxic providing a favourable cell environmentfor optimal adhesion and proliferation of ADSCs Becauseof this BCPHEMA can therefore be seen as a promisingmaterial for several biomedical applications including thedesign of 3D matrices to maintain a cellular niche for stemcell-mediated tissue regeneration


Conflict of Interests

The authors declare that there is no conflict of interests in theresults reported in the present paper

Acknowledgments

Andrea G P R Figueiredo and Susana C M Fernandesthank the Fundacao para a Ciencia e Tecnologia (Portugal)for their Scientific Research Grants (SFRHBPD632192009and SFRHBPD701192010 resp) cofinancing byPOPHESF Program The authors thank CICECO (Pest-CCTMLA00112013) and FCT for funding within the scopeof the ldquoNational Program for Scientific reequipmentrdquo Rede1509RME2005 REEQ515CTM2005 and Universityof the Basque Country for financial support (UPVEHUProject GIU 1016) The authors also acknowledge thetechnical and human support of General Research Services(SGIker) from the UPVEHU for the SEM analysis

References

[1] A Dufresne ldquoCellulose-Based Composites and Nanocompos-itesrdquo in Monomers Polymers and Composites From RenewableResources M N Belgacem and A Gandini Eds ElsevierAmsterdam Netherlands 2008

[2] D Klemm B Heublein H-P Fink and A Bohn ldquoCellulosefascinating biopolymer and sustainable raw materialrdquo Ange-wandte Chemie vol 44 no 22 pp 3358ndash3393 2005

[3] T Heinze and T Liebert ldquoCelluloses and polyoseshemicellu-losesrdquo in Polymer Science M Krzysztof and M Martin EdsElsevier Amsterdam Netherlands 2012

[4] D Klemm F Kramer S Moritz et al ldquoNanocelluloses a newfamily of nature-based materialsrdquo Angewandte Chemie vol 50no 24 pp 5438ndash5466 2011

[5] H P S Abdul Khalil A H Bhat and A F Ireana Yusra ldquoGreencomposites from sustainable cellulose nanofibrils a reviewrdquoCarbohydrate Polymers vol 87 no 2 pp 963ndash979 2012

[6] L M M Costa G M de Olyveira P Basmaji and L X FilholdquoBacterial cellulose towards functional medical materialsrdquo Jour-nal of Biomaterials and Tissue Engineering vol 2 no 3 pp 185ndash196 2012

[7] R J B Pinto M C Neves C P Neto and T TrindadeldquoComposites of cellulose and metal nanoparticlesrdquo inNanocompositesndashNew Trends and Developments F EbrahimiEd InTech Rijeka Croatia 2012

[8] P Carreira J A S Mendes E Trovatti et al ldquoUtilization ofresidues from agro-forest industries in the production of highvalue bacterial celluloserdquo Bioresource Technology vol 102 no15 pp 7354ndash7360 2011

[9] E Trovatti L S Serafim C S R Freire A J D Silvestre andC P Neto ldquoGluconacetobacter sacchari an efficient bacterialcellulose cell-factoryrdquo Carbohydrate Polymers vol 86 no 3 pp1417ndash1420 2011

[10] L Fu J Zhang and G Yang ldquoPresent status and applicationsof bacterial cellulose-based materials for skin tissue repairrdquoCarbohydrate Polymers vol 92 no 2 pp 1432ndash1442 2013

[11] L M M Costa G M de Olyveira B M Cherian A LLeao S F de Souza and M Ferreira ldquoBionanocompositesfrom electrospun PVApineapple nanofibersStryphnodendron

adstringens bark extract for medical applicationsrdquo IndustrialCrops and Products vol 41 no 1 pp 198ndash202 2013

[12] L M M Costa G M Olyveira P Basmaji et al ldquoNovelotolithsbacterial cellulose nanocomposites as a potential nat-ural product for direct dental pulp cappingrdquo Journal of Bioma-terials and Tissue Engineering vol 2 no 1 pp 48ndash53 2012

[13] E Trovatti C S R Freire P C Pinto et al ldquoBacterial cellulosemembranes applied in topical and transdermal delivery of lido-caine hydrochloride and ibuprofen in vitro diffusion studiesrdquoInternational Journal of Pharmaceutics vol 435 no 1 pp 83ndash87 2012

[14] J L Lopes J M Machado L Castanheira et al ldquoFriction andwear behaviour of bacterial cellulose against articular cartilagerdquoWear vol 271 no 9-10 pp 2328ndash2333 2011

[15] R J B Pinto P A A P Marques C P Neto T Trindade SDaina and P Sadocco ldquoAntibacterial activity of nanocompos-ites of silver and bacterial or vegetable cellulosic fibersrdquo ActaBiomaterialia vol 5 no 6 pp 2279ndash2289 2009

[16] R Hobzova M Duskova-Smrckova J Michalek E Kar-pushkin and P Gatenholm ldquoMethacrylate hydrogels reinforcedwith bacterial celluloserdquo Polymer International vol 61 no 7 pp1193ndash1201 2012

[17] Y Feng X Zhang Y ShenK Yoshino andW Feng ldquoAmechan-ically strong flexible and conductive film based on bacterial cel-lulosegraphene nanocompositerdquo Carbohydrate Polymers vol87 no 1 pp 644ndash649 2012

[18] G F Perotti H S Barud Y Messaddeq S J L Ribeiroand V R L Constantino ldquoBacterial cellulose-laponite claynanocompositesrdquo Polymer vol 52 no 1 pp 157ndash163 2011

[19] J Shah and R M Brown Jr ldquoTowards electronic paper displaysmade from microbial celluloserdquo Applied Microbiology andBiotechnology vol 66 no 4 pp 352ndash355 2005

[20] H S Barud J M A Caiut J Dexpert-Ghys Y Messaddeqand S J L Ribeiro ldquoTransparent bacterial cellulose-boehmite-epoxi-siloxane nanocompositesrdquo Composites A vol 43 no 6pp 973ndash977 2012

[21] J M A Caiut H D S Barud Y Messaddeq and S J L RibeiroldquoOptically transparent composites based on bacterial celluloseand boehmite siloxane andor a boehmite-siloxane systemrdquoPatent WO2012100315 2012

[22] E Trovatti L Oliveira C S R Freire et al ldquoNovel bacterialcellulose-acrylic resin nanocompositesrdquoComposites Science andTechnology vol 70 no 7 pp 1148ndash1153 2010

[23] S Gea E Bilotti C T Reynolds N Soykeabkeaw and TPeijs ldquoBacterial cellulose-poly(vinyl alcohol) nanocompositesprepared by an in-situ processrdquo Materials Letters vol 64 no8 pp 901ndash904 2010

[24] I M G Martins S P Magina L Oliveira et al ldquoNew biocom-posites based on thermoplastic starch and bacterial celluloserdquoComposites Science and Technology vol 69 no 13 pp 2163ndash2168 2009

[25] S C M Fernandes L Oliveira C S R Freire et al ldquoNoveltransparent nanocomposite films based on chitosan and bac-terial celluloserdquo Green Chemistry vol 11 no 12 pp 2023ndash20292009

[26] S C M Fernandes C S R Freire A J D Silvestre et alldquoTransparent chitosan films reinforced with a high content ofnanofibrillated celluloserdquo Carbohydrate Polymers vol 81 no 2pp 394ndash401 2010

[27] E Trovatti S C M Fernandes L Rubatat C S R Freire A JD Silvestre and C P Neto ldquoSustainable nanocomposite films


based on bacterial cellulose and pullulanrdquo Cellulose vol 19 no3 pp 729ndash737 2012

[28] A L Buyanov I V Gofman L G Revelrsquoskaya A K Khripunovand A A Tkachenko ldquoAnisotropic swelling and mechanicalbehavior of composite bacterial cellulose-poly(acrylamide oracrylamide-sodium acrylate) hydrogelsrdquo Journal of theMechan-ical Behavior of Biomedical Materials vol 3 no 1 pp 102ndash1112010

[29] N Halib M C I M Amin and I Ahmad ldquoUnique stimuliresponsive characteristics of electron beam synthesized bacte-rial celluloseacrylic acid compositerdquo Journal of Applied PolymerScience vol 116 no 5 pp 2920ndash2929 2010

[30] J Zhang J Rong W Li Z Lin and X Zhang ldquoPreparation andcharacterization of bacterial cellulosepolyacrylamide hydro-gelrdquo Acta Polymerica Sinica no 6 pp 602ndash607 2011

[31] F Kramer D Klemm D Schumann et al ldquoNanocellulosepolymer composites as innovative pool for (Bio)material devel-opmentrdquoMacromolecular Symposia vol 244 pp 136ndash148 2006

[32] M C I Mohd Amin N Ahmad N Halib and I AhmadldquoSynthesis and characterization of thermo- and pH-responsivebacterial celluloseacrylic acid hydrogels for drug deliveryrdquoCarbohydrate Polymers vol 88 no 2 pp 465ndash473 2012

[33] J Kopecek ldquoHydrogels from soft contact lenses and implantsto self-assembled nanomaterialsrdquo Journal of Polymer Science Avol 47 no 22 pp 5929ndash5946 2009

[34] T V Chirila ldquoAn overview of the development of artificialcorneas with porous skirts and the use of PHEMA for such anapplicationrdquo Biomaterials vol 22 no 24 pp 3311ndash3317 2001

[35] S Atzet S Curtin P Trinh S Bryant and B Ratner ldquoDegrad-able poly(2-hydroxyethyl methacrylate)-co-polycaprolactonehydrogels for tissue engineering scaffoldsrdquo Biomacromoleculesvol 9 no 12 pp 3370ndash3377 2008

[36] D Horak H Hlıdkova J Hradil M Lapcıkova and MSlouf ldquoSuperporous poly(2-hydroxyethyl methacrylate) basedscaffolds preparation and characterizationrdquo Polymer vol 49no 8 pp 2046ndash2054 2008

[37] S Hestrin and M Schramm ldquoSynthesis of cellulose by Aceto-bacter xylinummdashII Preparation of freeze-dried cells capable ofpolymerizing glucose to celluloserdquoTheBiochemical Journal vol58 no 2 pp 345ndash352 1954

[38] S C M Fernandes P Sadocco A Alonso-Varona et alldquoBioinspired antimicrobial and biocompatible bacterial cellu-lose membranes obtained by surface functionalization withaminoalkyl groupsrdquo ACS Applied Materials amp Interfaces vol 5no 8 pp 3290ndash3297 2013

[39] D Gulsen and A Chauhan ldquoEffect of water content on trans-parency swelling lidocaine diffusion in p-HEMA gelsrdquo Journalof Membrane Science vol 269 no 1-2 pp 35ndash48 2006

[40] D N S HonChemicalModification of LignocellulosicMaterialsMarcel Dekker New York NY USA 1996

[41] D Klemm Comprehensive Cellulose Chemistry Fundamentalsand Analytical Methods Wiley-VCH 1998

[42] N Nishioka T Itoh and M Uno ldquoThermal decomposition ofcellulosesynthetic polymer blends containing grafted productsIV Cellulosepoly(2-hydroxyethyl methacrylate) blendsrdquo Poly-mer Journal vol 31 no 12 pp 1218ndash1223 1999

[43] R K Bose and K K S Lau ldquoMechanical properties of ultrahighmolecular weight PHEMA hydrogels synthesized using initi-ated chemical vapor depositionrdquo Biomacromolecules vol 11 no8 pp 2116ndash2122 2010

[44] R Pertile S Moreira F Andrade L Domingues andM GamaldquoBacterial cellulose modified using recombinant proteins toimprove neuronal and mesenchymal cell adhesionrdquo Biotechnol-ogy Progress vol 28 no 2 pp 526ndash532 2012

[45] M E Gomes T Rada and R L Reis ldquoAdipose tissue-derivedstem cells and their application in bone and cartilage tissueengineeringrdquo Tissue Engineering B vol 15 no 2 pp 113ndash1252009

[46] A Sterodimas J De Faria B Nicaretta and I Pitanguy ldquoTissueengineering with adipose-derived stem cells (ADSCs) currentand future applicationsrdquo Journal of Plastic Reconstructive andAesthetic Surgery vol 63 no 11 pp 1886ndash1892 2010

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


(HEMA)

O

O

O O

O

O

O O OO

O O

OOO O

O

O

OH

OHOH

OH(PEGDA)

KPS in water70∘C 6 h

HO

(PHEMAPEGDA)

+ mn

o

m

p q

Figure 1 Schematic representation of HEMA polymerization in the presence of PEGDA to yield PHEMA cross-linked with PEGDA

[29 31 32] and 2-ethylhexyl acrylate [31] have already beenexplored in this context in particular for the development ofBCbased hydrogels

Poly(2-hydroxyethyl methacrylate) (PHEMA) is a versa-tile synthetic polymer with properties suited to a range ofapplications in particular biomedical applications includingsoft contact lenses [33] artificial corneas [34] degradablescaffolds for tissue engineering [35] and drug deliverysystems [36] BCPHEMA hydrogels have already beendescribed as part of two studies dealing with the preparationof BC based hydrogels by in situ polymerization of severalacrylic monomers In both cases the authors focus essentiallyon the swelling behaviour morphology and mechanicalproperties of the hydrogels Other important propertiessuch as thermal stability transparency crystallinity andbiocompatibility as well as their preparation in other formssuch as films or aerogels were not investigated and are alsoimportant for several applications

In the present study BCPHEMA nanocomposites in theform of thin films were prepared by in situ radical polymer-ization in the presence of poly(ethylene glycol) diacrylate(PEGDA) as cross-linker (Figure 1) The effect of the contentof monomer and cross-linker was evaluated The ensuingnanocomposites were characterized in terms of chemicalstructure crystallinity transparency morphology thermalstability mechanical properties and biocompatibility

2 Materials and Methods

21 Chemicals and Materials 2-Hydroxyethyl methacrylate((HEMA) 97 stabilized) and poly(ethylene glycol) diacry-late ((PEGDA) average Mn 258 stabilized) were purchasedfrom Sigma-Aldrich and used as received Potassium persul-fate ((KPS) 98 Panreac) was used as thermal initiator Allother reagents and solvents were of analytical grade and usedas received

Bacterial cellulose (BC) (tridimensional network of nano-and microfibrils with 10ndash200 nm width) in the form ofwet membranes was produced in our laboratory using theGluconacetobacter sacchari bacterial strain [8] and followingestablished procedures [37]

22 BCPHEMANanocomposites Preparation WetBCmem-branes (sim100mg dry weigh 4 times 4 cm2 and 08 cm thickness)were weighted and 60 of their water content was removedwith absorbent paper Drained BC membranes were put inErlenmeyers stoppedwith rubber septa and then purged withnitrogen At the same time aqueous solutions (5mL) withdifferent amounts ofmonomerHEMA (75 150 300mg) 12of KPS inititaor (ww relative to monomer) and PEGDA (01 and 5 (wcross-linkerwmonomer)) were prepared (Table 1) andalso purged with nitrogen (in an ice bath) for 30min Thenthe solutions were transferred with a syringe to the Erlen-meyers containing the drained BCmembranes After that themembranes were left to stand for 1 hour at room temperature(25∘C) until the complete absorptionincorporation of thesolutions Subsequently the reaction mixtures were left at70∘C (to induce in situ radical polymerization) for 6 hThenthe septum was pulled off and the BC membranes washedwith water (100mL) during 30min This washing procedurewas repeated three times The washed membranes wereplaced over Petri dishes and dried at 40∘C in a ventilated ovenfor 5ndash12 h The dried membranes were kept in a desiccatoruntil their use All experiments were made in triplicate andanalysed in the form of thin nanocomposite films Samplesof PHEMA and PHEMA cross-linked with PEGDA wereprepared under the same conditions in the absence of BC forcomparative purposes

Three samples from each series were freeze-dried andweighed PHEMAPEGDA and BC percent composition ofthe nanocomposites (Table 1) were estimated by difference tothe original BC weight




BCPHEMAPEGDA(1 3 0)

100 300

0 740 260

BCPHEMAPEGDA(1 3 001) 1 739 261

BCPHEMAPEGDA(1 3 005) 5 759 241


100 150

0 570 430

BCPHEMAPEGDA(1 15 001) 1 592 408

BCPHEMAPEGDA(1 15 005) 5 610 390


100 75

0 361 639

BCPHEMAPEGDA(1 075 001) 1 403 597

BCPHEMAPEGDA(1 075 005) 5 448 552











SR () =(119882

119904minus119882

119889)

119882

119889

times 100 (1)


119904is the weight



BC

BCPHEMAPEGDA

1 3 0 1 3 001 1 3 005

(a)


0

20

40

60

400 500 600 700

Tran

smitt

ance

()

Wavelength (nm)

BCPHEMAPEGDA

BCPHEMAPEGDA

BCPHEMAPEGDA

BCPHEMAPEGDA

BCPHEMAPEGDA

(1 3 005)

(1 15 005)

(1 3 001)

(1 3 0)

(1 075 005)

(b)















HEMA

600110016002100260031003600

BC

OHCH2

CH

CH

C-O(-C-O-C)

C-O(-C-O-H)

120575s HOH


C = O

120575 C-OH

PHEMAPEGDA (1 001)











OO

OO

OH

OH

OHHO 1

23

4 5

6

BC

C = O

C = O

C-1

C-4C-1

C-4

C-2 3 5

C-2 3 5

CH2OHC-6

C-6

OCH2

CH2OH

OCH2

Main chainCH2

Main chainCH2

CH3

CH3

050100150200120575 (ppm)

Clowast

Clowast

Clowast

m

n

PHEMAPEGDA (1 0)








2and CH




(a)

(b)





10 20 30 402120579 (∘)

PHEMAPEGDA

PHEMAPEGDA

BC

(1 0)

(1 005)

(a)

BCPHEMAPEGDA

BCPHEMAPEGDA

BCPHEMAPEGDA

2120579 (∘)10 20 30 40

(1 3 0)

(1 3 001)

(1 3 005)

(b)

BCPHEMAPEGDA

BCPHEMAPEGDA

BCPHEMAPEGDA

2120579 (∘)10 20 30 40

(1 15 0)

(1 15 001)

(1 15 005)

(c)

BCPHEMAPEGDA

BCPHEMAPEGDA

BCPHEMAPEGDA

2120579 (∘)10 20 30 40

(1 075 0)

(1 075 001)

(1 075 005)

(d)






2) 672 (HOndashCH

2ndash)




0

50

100

150

200

250

300

010 20 30 40 50

Swel

ling

ratio

()

Time (h)


(a)

0

50

100

150

200

250

1 2 3 4 5 6 70

Swel

ling

ratio

()

Time (h)


(b)









0

20

40

60

80

100

0 100 200 300 400 500 600 700 800

0 200 400 600 800Mas

s los

s (

)

Temperature (∘C)


(a)

0

20

40

60

80

100

0 100 200 300 400 500 600 700 800

Mas

s los

s (

)

Temperature (∘C)

0 200 400 600 800

BC



(b)








massloss at100∘C

Tdi(∘C)

Tdmax1(∘C)

Tdmax2(∘C)

BCPHEMAPEGDA(1 3 0) 336 272 384 434

BCPHEMAPEGDA(1 3 001) 179 274 388 442

BCPHEMAPEGDA(1 3 005) 179 250 373 434

BCPHEMAPEGDA(1 15 0) 295 276 395 443

BCPHEMAPEGDA(1 15 001) 225 266 387 440

BCPHEMAPEGDA(1 15 005) 281 257 373 430

BCPHEMAPEGDA(1 075 0) 303 276 389 442

BCPHEMAPEGDA(1 075 001) 206 272 390 441

BCPHEMAPEGDA(1 075 005) 244 235 386 433





BC

(Pa)

998400

14E + 09

14E + 10

Mod

ulus

E







24 48 72000102030405060708091011

Positive control

BC

Time (h)

Fold

of n

egat

ive c

ontro

l

lowastlowast lowast


lowastlowastlowast








BC







4 Conclusions






Acknowledgments


References

























































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials






BCPHEMAPEGDA(1 3 0)

100 300

0 740 260

BCPHEMAPEGDA(1 3 001) 1 739 261

BCPHEMAPEGDA(1 3 005) 5 759 241


100 150

0 570 430

BCPHEMAPEGDA(1 15 001) 1 592 408

BCPHEMAPEGDA(1 15 005) 5 610 390


100 75

0 361 639

BCPHEMAPEGDA(1 075 001) 1 403 597

BCPHEMAPEGDA(1 075 005) 5 448 552











SR () =(119882

119904minus119882

119889)

119882

119889

times 100 (1)


119904is the weight



BC

BCPHEMAPEGDA

1 3 0 1 3 001 1 3 005

(a)


0

20

40

60

400 500 600 700

Tran

smitt

ance

()

Wavelength (nm)

BCPHEMAPEGDA

BCPHEMAPEGDA

BCPHEMAPEGDA

BCPHEMAPEGDA

BCPHEMAPEGDA

(1 3 005)

(1 15 005)

(1 3 001)

(1 3 0)

(1 075 005)

(b)















HEMA

600110016002100260031003600

BC

OHCH2

CH

CH

C-O(-C-O-C)

C-O(-C-O-H)

120575s HOH


C = O

120575 C-OH

PHEMAPEGDA (1 001)











OO

OO

OH

OH

OHHO 1

23

4 5

6

BC

C = O

C = O

C-1

C-4C-1

C-4

C-2 3 5

C-2 3 5

CH2OHC-6

C-6

OCH2

CH2OH

OCH2

Main chainCH2

Main chainCH2

CH3

CH3

050100150200120575 (ppm)

Clowast

Clowast

Clowast

m

n

PHEMAPEGDA (1 0)








2and CH




(a)

(b)





10 20 30 402120579 (∘)

PHEMAPEGDA

PHEMAPEGDA

BC

(1 0)

(1 005)

(a)

BCPHEMAPEGDA

BCPHEMAPEGDA

BCPHEMAPEGDA

2120579 (∘)10 20 30 40

(1 3 0)

(1 3 001)

(1 3 005)

(b)

BCPHEMAPEGDA

BCPHEMAPEGDA

BCPHEMAPEGDA

2120579 (∘)10 20 30 40

(1 15 0)

(1 15 001)

(1 15 005)

(c)

BCPHEMAPEGDA

BCPHEMAPEGDA

BCPHEMAPEGDA

2120579 (∘)10 20 30 40

(1 075 0)

(1 075 001)

(1 075 005)

(d)






2) 672 (HOndashCH

2ndash)




0

50

100

150

200

250

300

010 20 30 40 50

Swel

ling

ratio

()

Time (h)


(a)

0

50

100

150

200

250

1 2 3 4 5 6 70

Swel

ling

ratio

()

Time (h)


(b)









0

20

40

60

80

100

0 100 200 300 400 500 600 700 800

0 200 400 600 800Mas

s los

s (

)

Temperature (∘C)


(a)

0

20

40

60

80

100

0 100 200 300 400 500 600 700 800

Mas

s los

s (

)

Temperature (∘C)

0 200 400 600 800

BC



(b)








massloss at100∘C

Tdi(∘C)

Tdmax1(∘C)

Tdmax2(∘C)

BCPHEMAPEGDA(1 3 0) 336 272 384 434

BCPHEMAPEGDA(1 3 001) 179 274 388 442

BCPHEMAPEGDA(1 3 005) 179 250 373 434

BCPHEMAPEGDA(1 15 0) 295 276 395 443

BCPHEMAPEGDA(1 15 001) 225 266 387 440

BCPHEMAPEGDA(1 15 005) 281 257 373 430

BCPHEMAPEGDA(1 075 0) 303 276 389 442

BCPHEMAPEGDA(1 075 001) 206 272 390 441

BCPHEMAPEGDA(1 075 005) 244 235 386 433





BC

(Pa)

998400

14E + 09

14E + 10

Mod

ulus

E







24 48 72000102030405060708091011

Positive control

BC

Time (h)

Fold

of n

egat

ive c

ontro

l

lowastlowast lowast


lowastlowastlowast








BC







4 Conclusions






Acknowledgments


References

























































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




BC

BCPHEMAPEGDA

1 3 0 1 3 001 1 3 005

(a)


0

20

40

60

400 500 600 700

Tran

smitt

ance

()

Wavelength (nm)

BCPHEMAPEGDA

BCPHEMAPEGDA

BCPHEMAPEGDA

BCPHEMAPEGDA

BCPHEMAPEGDA

(1 3 005)

(1 15 005)

(1 3 001)

(1 3 0)

(1 075 005)

(b)















HEMA

600110016002100260031003600

BC

OHCH2

CH

CH

C-O(-C-O-C)

C-O(-C-O-H)

120575s HOH


C = O

120575 C-OH

PHEMAPEGDA (1 001)











OO

OO

OH

OH

OHHO 1

23

4 5

6

BC

C = O

C = O

C-1

C-4C-1

C-4

C-2 3 5

C-2 3 5

CH2OHC-6

C-6

OCH2

CH2OH

OCH2

Main chainCH2

Main chainCH2

CH3

CH3

050100150200120575 (ppm)

Clowast

Clowast

Clowast

m

n

PHEMAPEGDA (1 0)








2and CH




(a)

(b)





10 20 30 402120579 (∘)

PHEMAPEGDA

PHEMAPEGDA

BC

(1 0)

(1 005)

(a)

BCPHEMAPEGDA

BCPHEMAPEGDA

BCPHEMAPEGDA

2120579 (∘)10 20 30 40

(1 3 0)

(1 3 001)

(1 3 005)

(b)

BCPHEMAPEGDA

BCPHEMAPEGDA

BCPHEMAPEGDA

2120579 (∘)10 20 30 40

(1 15 0)

(1 15 001)

(1 15 005)

(c)

BCPHEMAPEGDA

BCPHEMAPEGDA

BCPHEMAPEGDA

2120579 (∘)10 20 30 40

(1 075 0)

(1 075 001)

(1 075 005)

(d)






2) 672 (HOndashCH

2ndash)




0

50

100

150

200

250

300

010 20 30 40 50

Swel

ling

ratio

()

Time (h)


(a)

0

50

100

150

200

250

1 2 3 4 5 6 70

Swel

ling

ratio

()

Time (h)


(b)









0

20

40

60

80

100

0 100 200 300 400 500 600 700 800

0 200 400 600 800Mas

s los

s (

)

Temperature (∘C)


(a)

0

20

40

60

80

100

0 100 200 300 400 500 600 700 800

Mas

s los

s (

)

Temperature (∘C)

0 200 400 600 800

BC



(b)








massloss at100∘C

Tdi(∘C)

Tdmax1(∘C)

Tdmax2(∘C)

BCPHEMAPEGDA(1 3 0) 336 272 384 434

BCPHEMAPEGDA(1 3 001) 179 274 388 442

BCPHEMAPEGDA(1 3 005) 179 250 373 434

BCPHEMAPEGDA(1 15 0) 295 276 395 443

BCPHEMAPEGDA(1 15 001) 225 266 387 440

BCPHEMAPEGDA(1 15 005) 281 257 373 430

BCPHEMAPEGDA(1 075 0) 303 276 389 442

BCPHEMAPEGDA(1 075 001) 206 272 390 441

BCPHEMAPEGDA(1 075 005) 244 235 386 433





BC

(Pa)

998400

14E + 09

14E + 10

Mod

ulus

E







24 48 72000102030405060708091011

Positive control

BC

Time (h)

Fold

of n

egat

ive c

ontro

l

lowastlowast lowast


lowastlowastlowast








BC







4 Conclusions






Acknowledgments


References

























































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




HEMA

600110016002100260031003600

BC

OHCH2

CH

CH

C-O(-C-O-C)

C-O(-C-O-H)

120575s HOH


C = O

120575 C-OH

PHEMAPEGDA (1 001)











OO

OO

OH

OH

OHHO 1

23

4 5

6

BC

C = O

C = O

C-1

C-4C-1

C-4

C-2 3 5

C-2 3 5

CH2OHC-6

C-6

OCH2

CH2OH

OCH2

Main chainCH2

Main chainCH2

CH3

CH3

050100150200120575 (ppm)

Clowast

Clowast

Clowast

m

n

PHEMAPEGDA (1 0)








2and CH




(a)

(b)





10 20 30 402120579 (∘)

PHEMAPEGDA

PHEMAPEGDA

BC

(1 0)

(1 005)

(a)

BCPHEMAPEGDA

BCPHEMAPEGDA

BCPHEMAPEGDA

2120579 (∘)10 20 30 40

(1 3 0)

(1 3 001)

(1 3 005)

(b)

BCPHEMAPEGDA

BCPHEMAPEGDA

BCPHEMAPEGDA

2120579 (∘)10 20 30 40

(1 15 0)

(1 15 001)

(1 15 005)

(c)

BCPHEMAPEGDA

BCPHEMAPEGDA

BCPHEMAPEGDA

2120579 (∘)10 20 30 40

(1 075 0)

(1 075 001)

(1 075 005)

(d)






2) 672 (HOndashCH

2ndash)




0

50

100

150

200

250

300

010 20 30 40 50

Swel

ling

ratio

()

Time (h)


(a)

0

50

100

150

200

250

1 2 3 4 5 6 70

Swel

ling

ratio

()

Time (h)


(b)









0

20

40

60

80

100

0 100 200 300 400 500 600 700 800

0 200 400 600 800Mas

s los

s (

)

Temperature (∘C)


(a)

0

20

40

60

80

100

0 100 200 300 400 500 600 700 800

Mas

s los

s (

)

Temperature (∘C)

0 200 400 600 800

BC



(b)








massloss at100∘C

Tdi(∘C)

Tdmax1(∘C)

Tdmax2(∘C)

BCPHEMAPEGDA(1 3 0) 336 272 384 434

BCPHEMAPEGDA(1 3 001) 179 274 388 442

BCPHEMAPEGDA(1 3 005) 179 250 373 434

BCPHEMAPEGDA(1 15 0) 295 276 395 443

BCPHEMAPEGDA(1 15 001) 225 266 387 440

BCPHEMAPEGDA(1 15 005) 281 257 373 430

BCPHEMAPEGDA(1 075 0) 303 276 389 442

BCPHEMAPEGDA(1 075 001) 206 272 390 441

BCPHEMAPEGDA(1 075 005) 244 235 386 433





BC

(Pa)

998400

14E + 09

14E + 10

Mod

ulus

E







24 48 72000102030405060708091011

Positive control

BC

Time (h)

Fold

of n

egat

ive c

ontro

l

lowastlowast lowast


lowastlowastlowast








BC







4 Conclusions






Acknowledgments


References

























































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




OO

OO

OH

OH

OHHO 1

23

4 5

6

BC

C = O

C = O

C-1

C-4C-1

C-4

C-2 3 5

C-2 3 5

CH2OHC-6

C-6

OCH2

CH2OH

OCH2

Main chainCH2

Main chainCH2

CH3

CH3

050100150200120575 (ppm)

Clowast

Clowast

Clowast

m

n

PHEMAPEGDA (1 0)








2and CH




(a)

(b)





10 20 30 402120579 (∘)

PHEMAPEGDA

PHEMAPEGDA

BC

(1 0)

(1 005)

(a)

BCPHEMAPEGDA

BCPHEMAPEGDA

BCPHEMAPEGDA

2120579 (∘)10 20 30 40

(1 3 0)

(1 3 001)

(1 3 005)

(b)

BCPHEMAPEGDA

BCPHEMAPEGDA

BCPHEMAPEGDA

2120579 (∘)10 20 30 40

(1 15 0)

(1 15 001)

(1 15 005)

(c)

BCPHEMAPEGDA

BCPHEMAPEGDA

BCPHEMAPEGDA

2120579 (∘)10 20 30 40

(1 075 0)

(1 075 001)

(1 075 005)

(d)






2) 672 (HOndashCH

2ndash)




0

50

100

150

200

250

300

010 20 30 40 50

Swel

ling

ratio

()

Time (h)


(a)

0

50

100

150

200

250

1 2 3 4 5 6 70

Swel

ling

ratio

()

Time (h)


(b)









0

20

40

60

80

100

0 100 200 300 400 500 600 700 800

0 200 400 600 800Mas

s los

s (

)

Temperature (∘C)


(a)

0

20

40

60

80

100

0 100 200 300 400 500 600 700 800

Mas

s los

s (

)

Temperature (∘C)

0 200 400 600 800

BC



(b)








massloss at100∘C

Tdi(∘C)

Tdmax1(∘C)

Tdmax2(∘C)

BCPHEMAPEGDA(1 3 0) 336 272 384 434

BCPHEMAPEGDA(1 3 001) 179 274 388 442

BCPHEMAPEGDA(1 3 005) 179 250 373 434

BCPHEMAPEGDA(1 15 0) 295 276 395 443

BCPHEMAPEGDA(1 15 001) 225 266 387 440

BCPHEMAPEGDA(1 15 005) 281 257 373 430

BCPHEMAPEGDA(1 075 0) 303 276 389 442

BCPHEMAPEGDA(1 075 001) 206 272 390 441

BCPHEMAPEGDA(1 075 005) 244 235 386 433





BC

(Pa)

998400

14E + 09

14E + 10

Mod

ulus

E







24 48 72000102030405060708091011

Positive control

BC

Time (h)

Fold

of n

egat

ive c

ontro

l

lowastlowast lowast


lowastlowastlowast








BC







4 Conclusions






Acknowledgments


References

























































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




(a)

(b)





10 20 30 402120579 (∘)

PHEMAPEGDA

PHEMAPEGDA

BC

(1 0)

(1 005)

(a)

BCPHEMAPEGDA

BCPHEMAPEGDA

BCPHEMAPEGDA

2120579 (∘)10 20 30 40

(1 3 0)

(1 3 001)

(1 3 005)

(b)

BCPHEMAPEGDA

BCPHEMAPEGDA

BCPHEMAPEGDA

2120579 (∘)10 20 30 40

(1 15 0)

(1 15 001)

(1 15 005)

(c)

BCPHEMAPEGDA

BCPHEMAPEGDA

BCPHEMAPEGDA

2120579 (∘)10 20 30 40

(1 075 0)

(1 075 001)

(1 075 005)

(d)






2) 672 (HOndashCH

2ndash)




0

50

100

150

200

250

300

010 20 30 40 50

Swel

ling

ratio

()

Time (h)


(a)

0

50

100

150

200

250

1 2 3 4 5 6 70

Swel

ling

ratio

()

Time (h)


(b)









0

20

40

60

80

100

0 100 200 300 400 500 600 700 800

0 200 400 600 800Mas

s los

s (

)

Temperature (∘C)


(a)

0

20

40

60

80

100

0 100 200 300 400 500 600 700 800

Mas

s los

s (

)

Temperature (∘C)

0 200 400 600 800

BC



(b)








massloss at100∘C

Tdi(∘C)

Tdmax1(∘C)

Tdmax2(∘C)

BCPHEMAPEGDA(1 3 0) 336 272 384 434

BCPHEMAPEGDA(1 3 001) 179 274 388 442

BCPHEMAPEGDA(1 3 005) 179 250 373 434

BCPHEMAPEGDA(1 15 0) 295 276 395 443

BCPHEMAPEGDA(1 15 001) 225 266 387 440

BCPHEMAPEGDA(1 15 005) 281 257 373 430

BCPHEMAPEGDA(1 075 0) 303 276 389 442

BCPHEMAPEGDA(1 075 001) 206 272 390 441

BCPHEMAPEGDA(1 075 005) 244 235 386 433





BC

(Pa)

998400

14E + 09

14E + 10

Mod

ulus

E







24 48 72000102030405060708091011

Positive control

BC

Time (h)

Fold

of n

egat

ive c

ontro

l

lowastlowast lowast


lowastlowastlowast








BC







4 Conclusions






Acknowledgments


References

























































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




10 20 30 402120579 (∘)

PHEMAPEGDA

PHEMAPEGDA

BC

(1 0)

(1 005)

(a)

BCPHEMAPEGDA

BCPHEMAPEGDA

BCPHEMAPEGDA

2120579 (∘)10 20 30 40

(1 3 0)

(1 3 001)

(1 3 005)

(b)

BCPHEMAPEGDA

BCPHEMAPEGDA

BCPHEMAPEGDA

2120579 (∘)10 20 30 40

(1 15 0)

(1 15 001)

(1 15 005)

(c)

BCPHEMAPEGDA

BCPHEMAPEGDA

BCPHEMAPEGDA

2120579 (∘)10 20 30 40

(1 075 0)

(1 075 001)

(1 075 005)

(d)






2) 672 (HOndashCH

2ndash)




0

50

100

150

200

250

300

010 20 30 40 50

Swel

ling

ratio

()

Time (h)


(a)

0

50

100

150

200

250

1 2 3 4 5 6 70

Swel

ling

ratio

()

Time (h)


(b)









0

20

40

60

80

100

0 100 200 300 400 500 600 700 800

0 200 400 600 800Mas

s los

s (

)

Temperature (∘C)


(a)

0

20

40

60

80

100

0 100 200 300 400 500 600 700 800

Mas

s los

s (

)

Temperature (∘C)

0 200 400 600 800

BC



(b)








massloss at100∘C

Tdi(∘C)

Tdmax1(∘C)

Tdmax2(∘C)

BCPHEMAPEGDA(1 3 0) 336 272 384 434

BCPHEMAPEGDA(1 3 001) 179 274 388 442

BCPHEMAPEGDA(1 3 005) 179 250 373 434

BCPHEMAPEGDA(1 15 0) 295 276 395 443

BCPHEMAPEGDA(1 15 001) 225 266 387 440

BCPHEMAPEGDA(1 15 005) 281 257 373 430

BCPHEMAPEGDA(1 075 0) 303 276 389 442

BCPHEMAPEGDA(1 075 001) 206 272 390 441

BCPHEMAPEGDA(1 075 005) 244 235 386 433





BC

(Pa)

998400

14E + 09

14E + 10

Mod

ulus

E







24 48 72000102030405060708091011

Positive control

BC

Time (h)

Fold

of n

egat

ive c

ontro

l

lowastlowast lowast


lowastlowastlowast








BC







4 Conclusions






Acknowledgments


References

























































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




0

50

100

150

200

250

300

010 20 30 40 50

Swel

ling

ratio

()

Time (h)


(a)

0

50

100

150

200

250

1 2 3 4 5 6 70

Swel

ling

ratio

()

Time (h)


(b)









0

20

40

60

80

100

0 100 200 300 400 500 600 700 800

0 200 400 600 800Mas

s los

s (

)

Temperature (∘C)


(a)

0

20

40

60

80

100

0 100 200 300 400 500 600 700 800

Mas

s los

s (

)

Temperature (∘C)

0 200 400 600 800

BC



(b)








massloss at100∘C

Tdi(∘C)

Tdmax1(∘C)

Tdmax2(∘C)

BCPHEMAPEGDA(1 3 0) 336 272 384 434

BCPHEMAPEGDA(1 3 001) 179 274 388 442

BCPHEMAPEGDA(1 3 005) 179 250 373 434

BCPHEMAPEGDA(1 15 0) 295 276 395 443

BCPHEMAPEGDA(1 15 001) 225 266 387 440

BCPHEMAPEGDA(1 15 005) 281 257 373 430

BCPHEMAPEGDA(1 075 0) 303 276 389 442

BCPHEMAPEGDA(1 075 001) 206 272 390 441

BCPHEMAPEGDA(1 075 005) 244 235 386 433





BC

(Pa)

998400

14E + 09

14E + 10

Mod

ulus

E







24 48 72000102030405060708091011

Positive control

BC

Time (h)

Fold

of n

egat

ive c

ontro

l

lowastlowast lowast


lowastlowastlowast








BC







4 Conclusions






Acknowledgments


References

























































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




0

20

40

60

80

100

0 100 200 300 400 500 600 700 800

0 200 400 600 800Mas

s los

s (

)

Temperature (∘C)


(a)

0

20

40

60

80

100

0 100 200 300 400 500 600 700 800

Mas

s los

s (

)

Temperature (∘C)

0 200 400 600 800

BC



(b)








massloss at100∘C

Tdi(∘C)

Tdmax1(∘C)

Tdmax2(∘C)

BCPHEMAPEGDA(1 3 0) 336 272 384 434

BCPHEMAPEGDA(1 3 001) 179 274 388 442

BCPHEMAPEGDA(1 3 005) 179 250 373 434

BCPHEMAPEGDA(1 15 0) 295 276 395 443

BCPHEMAPEGDA(1 15 001) 225 266 387 440

BCPHEMAPEGDA(1 15 005) 281 257 373 430

BCPHEMAPEGDA(1 075 0) 303 276 389 442

BCPHEMAPEGDA(1 075 001) 206 272 390 441

BCPHEMAPEGDA(1 075 005) 244 235 386 433





BC

(Pa)

998400

14E + 09

14E + 10

Mod

ulus

E







24 48 72000102030405060708091011

Positive control

BC

Time (h)

Fold

of n

egat

ive c

ontro

l

lowastlowast lowast


lowastlowastlowast








BC







4 Conclusions






Acknowledgments


References

























































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials





BC

(Pa)

998400

14E + 09

14E + 10

Mod

ulus

E







24 48 72000102030405060708091011

Positive control

BC

Time (h)

Fold

of n

egat

ive c

ontro

l

lowastlowast lowast


lowastlowastlowast








BC







4 Conclusions






Acknowledgments


References

























































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




BC







4 Conclusions






Acknowledgments


References

























































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials






Acknowledgments


References

























































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



research article biocompatible bacterial cellulose-poly(2

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