International Journal of Biological Macromolecules 51 (2012) 1127– 1133
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International Journal of Biological Macromolecules
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ChitosanTPP microparticles obtained by microemulsion method applied in
controlled release of heparin
Alessandro F Martins ∗ Daiane M de Oliveira Antonio GB Pereira Adley F Rubira Edvani C Muniz
Grupo de Materiais Poliméricos e Compósitos GMPC Departamento de Química Universidade Estadual de Maringá UEM – Av Colombo 5790 – CEP 87020900 Maringá Paraná
Brazil
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Article history
Received 18 June 2012
Received in revised form 4 August 2012
Accepted 28 August 2012
Available online 2 September 2012
Keywords
Chitosan
Heparin
Controlled release
Tripolyphosphate
Microparticles
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This work deals with the preparation of chitosantripolyphosphate microparticles (CHTTPP) using
microemulsion system based on waterbenzyl alcohol The morphology of the microparticles was eval
uated by scanning electron microscopy (SEM) The microparticles were also characterized through
infrared spectroscopy (FTIR) and wideangle Xray scattering (WAXS) The morphology and crystallinity
of microparticles depended mainly on CHTTPP ratio Studies of controlled release of HP were evaluated
in distilled water and in simulated gastric fluid Besides the profile of HP releasing could be tailored by
tuning the CHTTPP molar ratio Finally these prospective results allow the particles to be employed as
sitespecific HP controlled release system
© 2012 Elsevier BV
1 Introduction
Chitosan (CHT) is a nontoxic polymer obtained from deacetyla
tion of chitin [12] This polymer presents excellent biocompatibil
ity biodegradability and antimicrobial activity [3] Thus CHT has
been studied for many medical applications such as tissue engi
neering and drug delivery systems [1–6] As the CHT possesses
higher adsorption capacity than chitin therefore the CHTbased
materials could be utilized in water purification systems [7] The
TPP is a nontoxic polyanion which interacts with CHT through
electrostatic forces The protonated amine groups in CHT interact
with the negatively charged ions on TPP through ionic interactions
creating ionic crosslinked networks [8–10] Microparticles of CHT
crosslinked with tripolyphosphate (TPP) showed significant results
in adsorption of ions Copper(II) [8] Lead(II) [9] and Uranium [10]
In the intestinal environment CHTTPP particles showed
potential for specific delivering of Papain [11] Acyclovir (antivi
ral drug) [12] and polyphenolic antioxidants such as Catechin
[13] Chitosancyclodextrin nanoparticles were also used as
devices for controlled release of heparin (HP) [14] The low
encapsulation efficiency and high association of the drug with chi
tosancyclodextrin nanoparticles impaired the release of HP [14]
Chitosangenipin microspheres showed potential for specific deliv
ering of low molecular weight heparin (LMWHP) in the region of the
∗ Corresponding author Tel +55 44 3011 3676 fax +55 44 3011 4125
Email address afmartins50@yahoocombr (AF Martins)
gastrointestinal tract [15] However it is known that LMWHP does
not present effective anticoagulant activity [16]
The molecule of HP consists of sulfated
dglucosamine units
joined in alternating sequence by
␣(14)glycosidic linkages to
either
dglucuronic and
liduronic acid [17–19] Due to the pres
ence of carboxyl and sulfate groups HP has the highest negative
charge density of any known biological polyanion [19] The HP
presents interesting properties such as biodegradability biocom
patibility stimulates cell growth and inhibits blood coagulation so
it is widely used in pharmaceutical and medical fields [31718]
The aims of this study were to obtain CHTTPP particles through
microemulsion method at different pH and CHTTPP ratios using
the system waterbenzyl alcohol to encapsulate the HP on such
particles and to evaluate the profiles of HP release at different pH
conditions
2 Experimental
21 Materials
Chitosan (CAS 9012764) with deacetylation degree equal
to 85 and average molecular weight of 87
×
103 g mol−1 was
purchased from GoldenShell Biochemical (China) benzyl alco
hol (CAS 100516) and methylene blue (CAS 97130831) were
both purchased from Sigma sodium tripolyphosphate (85) (CAS
9010086) was purchased from Acros (New Jersey USA) Heparin
sodium (CAS 9041081) was kindly supplied by Kin Master (Passo
Fundo Brazil) Other reactants such as sodium hydroxide sodium
01418130 © 2012 Elsevier BV
httpdxdoiorg101016jijbiomac201208032
Open access under the Elsevier OA license
Open access under the Elsevier OA license 1128 AF Martins et al International Journal of Biological Macromolecules 51 (2012) 1127– 1133
Table 1
Composition of the microemulsion system (WBnOH) the volumes of each solution
CHTTPP molar ratio and pHs used to obtain of the particles
CHTTPP molar ratio
151 (pH 2) 91 (pH 2) 151 (pH 5) 91 (pH 5)
CHT (cm−3) 20 20 20 20
TPP (cm−3) 3535
chloride hydrochloric acid ethanol and acetone were also utilized
in this work All reactants were used as received thus without
further purification
22 Particles preparation
Particles of CHTTPP were prepared based on a microemulsion
system using waterbenzyl alcohol (WBnOH) [20] For preparing
the CHTTPP particles separated solutions (20 cm−3) of CHT (04 g
or 248 mmol per repeating unit being considered only the deacety
lated residues) and TPP (047 g or 109 mmol) at 20 wtvol were
prepared at pH 2 and pH 5 The pH was adjusted by either sodium
hydroxide or hydrochloric acid (10 or 010 mol L−1) solutions The
previously prepared solution of CHT (20 cm−3) was mixed with
benzyl alcohol keeping the volume ratio at 14 (WBnOH) The mix
ture was initially kept under stirring at 6000 rpm during 10 min and
then increased to 14000 rpm Afterwards 30 or 50 cm−3 (TPP solu
tion) was slowly dripped and the system was kept under stirring by
further 10 min Finally the particles of CHTTPP were precipitated
and washed in acetone vacuum filtered and dried at 30 ◦C for 24 h
The volume of each solution and CHTTPP molar ratios as well as
the pH in which the particles were prepared are summarized in
Table 1 The label CHTTPPx–y was used for correlating the pH(x)
and volume (y) of TPP solution used for preparing the particles to
the studied properties
23 Particles characterization
231 Scanning electron microscopy (SEM)
The morphology of particles was investigated through analy
sis of SEM images (Shimadzu model SS 550) The particles were
sputtercoated with a thin layer of gold for allowing the SEM
visualization Images were taken by applying an electron beam
accelerating voltage of 10–15 kV The particles average diameters
were calculated by analysis of SEM images using the software Size
Meter© version 11 with differentiation threshold set according to
the image scale
232 Wide angle Xray scattering (WAXS)
The WAXS profiles were recorded on a diffractometer Shimadzu
model XRD600 equipped with a Nifiltered CuK␣ radiation The
WAXS profiles were collected in the scattering range 2
5–70◦
with resolution of 002◦ at a scanning speed of 2◦ min−1 The anal
yses were performed by applying an accelerating voltage of 40 kV
and a current intensity of 30 mA
233 Fouriertransform infrared spectroscopy (FTIR)
FTIR spectra were recorded using a Fourier transform infrared
spectrophotometer (Shimadzu Scientific Instruments Model 8300
Japan) operating from 4000 to 500 cm−1 at resolution of 4 cm−1
FTIR spectra were obtained from KBr pellets For comparison the
raw CHT and HP were also characterized by the FTIR technique
24 Loading of HP on CHTTPP particles
10 g of each sample (CHTTPPx–y particles) was dispersed in
ca 90 cm3 of HClH2O solution at (pH 2 or pH 5) under stirring
at 1000 rpm Just after 10 cm3 of HP solution (10 mg cm−3) was
slowly dripped The system was kept under stirring (1000 rpm) over
24 h at room temperature So the loaded particles were removed by
centrifugation (14000 rpm) at 4 ◦C vacuum filtered washed with
ethanol and lyophilized for 24 h at
−55 ◦C The supernatant was
analyzed through UV spectroscopy technique (at

567 nm using
a UVVis Femto model 800Xi Brazil) to estimate the loading effi
ciency Aliquots of 100
␮L of supernatant were directly added to
40 cm3 of an aqueous solution of methylene blue (MB) (50 mg L−1)
according to methodology described by Farndale et al [21] and
Martins et al [3] The measurements of absorbance of the complex
MBHP were performed immediately after homogenization of the
samples that occurred quickly after mixing Using a previously built
analytical curve the concentration of HP remained in the super
natant was calculated [3] The analytical curve was designed from
standard HP solutions varying from 020 to 70 mg L−1 using dis
tilled water as solvent (pH
≈
55–60) Such analytical curve was
made based on increasing absorbance of the complex of MBHP
with increasing concentration of HP The value of linear correla
tion coefficient (R2) for such curve was 0987 The encapsulation
efficiency was calculated using the following equation
Encapsulation efficiency [HPi]
−
[HPs]
[HPi]
×
100 (1)
where [HPi] is initial amount of heparin and [HPs] is the amount of
heparin in the supernatant
25 Characterization of the loaded particles
251 FTIR spectroscopy
The HPloaded CHT–TPP particles were also characterized by
FTIR spectroscopy in the same way as already described for non
loaded particles
252 Thermogravimetric (TGADTG) analysis
TGA was performed from 25 ◦C to 750 ◦C at a heating rate of
10 ◦C min−1 under N2(g) flowing at 50 mL min−1 in a TGA50 Ther
mogravimetry Analyzer (Netzch model STA 409PG4G Luxx USA)
26 In vitro heparin (HP) release
The in vitro HP release studies were performed in two dif
ferent environments simulated gastric fluid (SGF 20 g NaCl and
70 cm−3 HCl in 1000 cm−3 of water pH 12) and distilled water
(pH
≈
55–60) both without the presence of enzymes In a dissolu
tor apparatus 020 g of loaded particles were deposited in a sealed
flask with 50 cm−3 of SGF or distilled water under constant stirring
(60 rpm) at 37 ◦C At a desired time interval an aliquot (100
␮L)
was removed from the flask and directly added to 40 cm3 of aque
ous MB solution (50 mg L−1) to quantify the released amount of
drug through UV measures as described in Section 24 In this case
analytical curve for HP solution at SGF and at distilled water were
built in the HP conc range of 020–70 mg L−1 [321] The linear cor
relation coefficient (R2) for the analytical curve using the SGF as
solvent was of 0986 The fraction released of HP was calculated
from the following equation
Fraction released
amount released
amount encapsulated
×
100 (2)AF Martins et al International Journal of Biological Macromolecules 51 (2012) 1127– 1133 1129
Fig 1 SEM images of the CHTTPP2–3 (a and b) and CHTTPP2–5 (c and d) particles
3 Results and discussion
31 Particles characterization
311 Scanning electron microscopy (SEM)
SEM images in Figs 1 and 2 allow observing that the morphology
of obtained particles is dependent on CHTTPP molar ratio and on
pH of feed solution The lower CHTTPP ratio at pH 2 (see Table 1)
did not favor the formation of small particles due to coalescence
but favors in fact irregularly shaped large clusters as showed in
Fig 1c and d Therefore those samples were not used for further
studies in this work The values of averaged particles size obtained
after different runs are presented in Table 2
The samples obtained from feed solution at pH 5 CHTTPP5–3
and CHTTPP5–5 did not coalesce as those prepared at pH 2 (com
pare the Figs 1 and 2) However it could be verified that the lower
CHTTPP molar ratio (at pH 5) favors the formation of more com
pacted particles see Fig 2a–c Therefore the CHTTPP ratio and the
pH clearly influenced the size and porosity of obtained particles In
general the CHTTPP particles presented irregular shape
312 WAXS profiles
Fig 3 shows the WAXS profiles of CHT and of CHTTPP particles at
three different formulations One could observe the CHTTPP par
ticles showed important differences in the crystallinity profile as
compared to pure CHT The diffraction peaks that appear in WAXS
profile of CHT (Fig 3a) at 2
105◦ 199◦ 439◦ and 643◦ were
Table 2
Average size of CHTTPP particles
Particles Particles size (␮m)
3 cm−3 (TPP) 5 cm−3 (TPP)
CHTTPP2 923
±
38 –
CHTTPP5 726
±
23 1056
±
42
attributed to the crystalline regions formed by hydrogen bonds
among the amino and hydroxyl groups on CHT chains [1722] It is
possible to verify on profiles presented in Fig 3 that the CHTTPP2–3
and CHTTPP5–3 particles presented higher crystallinity than the
CHTTPP5–5 ones fact directly associated to CHTTPP molar ratio
The lower crosslinking density (related to the used amount of TPP)
the higher is the CHT chains mobility feature that contributes to the
reorganization of CHT chains during the formation of CHTTPP2–3
and CHTTPP5–3 particles
The CHT chains reorganization is evidenced by the intense peaks
that appear at 2
122◦ 440◦ and 645◦ (Fig 3 curves b and c
on) Piai et al [22] and Fajardo et al [23] observed reorganiza
tion in polyelectrolyte complexes (PECs) constituted by CHT and
chondroitin sulfate by analyzing the diffraction peaks at 2
438◦
and 642◦ in WAXS profile of such PECs The high intensity of such
new peaks in Fig 3 related to WAXS profile of raw CHT (curve a)
was attributed to the large extension of Hbonds among CHT–CHT
CHT–TPP and TPP–TPP chain segments Unlike the amino groups
of CHT which possessed pKa ≈
65 the TPP anion presents five
pKa (pKa1 10 pKa2 20 pKa3 279 pKa4 647 and pKa5 924)
according to Shu and Zhu [24] So the TPP anion can contribute
to the increase the intermolecular forces in the CHTTPP particles
since not all of phosphate groups are ionized in acid medium [24]
Fig 4 depicts the proposed scheme for the aforementioned
interactions In light of this the reorganization of CHT chains is
favored when the used amount of TPP is not enough to neutralize
the density of positive charges on CHT that prevail as +NH3
Besides the large extent of positive charges due to the high
CHTTPP molar ratio on CHTTPP2–3 and CHTTPP5–3 particles
could induce the appearance of domains with electrostatic repul
sion (Fig 4) These repulsion sites could be minimized with
structural reorganization process increasing the density of interac
tions through Hbonds on CHTTPP2–3 and CHTTPP5–3 particles
(Fig 4) This fact would explain the higher crystallinity of those
samples related to CHTTPP5–51130 AF Martins et al International Journal of Biological Macromolecules 51 (2012) 1127– 1133
Fig 2 SEM images of the CHTTPP5–3 (a and b) and CHTTPP5–5 (c and d) particles
On the other hand from the curve (d) on Fig 3 it is possible
to observe that CHTTPP5–5 particles are mostly amorphous fact
proved by the occurrence of a halo with maximum at 2
218◦ and
also by the absence of peaks at 2
122◦ 440◦ and 645◦ as com
pared to the WAXS profiles (curves b and c) In this way the higher
amount of TPP used in preparation of CHTTPP particles (Table 1)
the higher is the density of physical crosslinking This fact provides
larger rigidity of the chains which hinders the reorganization of
CHT chains in CHTTPP5–5 particles
From the analysis of SEM image from CHTTPP5–5 particles
(Fig 2d) one can be inferred that the higher content of TPP
(50 cm−3) provides rigidity to the CHT chains preventing its
Fig 3 WAXS profiles of precursors (CHT and TPP) and CHTTPP particles
structural reorganization and leading to particles with highly
uneven shape Therefore the low crystallinity and high roughness
of CHTTPP5–5 sample in relation to the others was mainly due
to its low CHTTPP molar ratio
Additionally the structural reorganization observed in the
WAXS profiles (curves b and c) was confirmed by the absences of
the diffractions peaks at 2
440◦ and 645◦ in WAXS profile of
pure sodium tripolyphosphate (curve e)
313 FTIR spectroscopy
The CHTTPP particles were characterized through FTIR spec
troscopy and the spectra are presented in Fig 5 The FTIR spectrum
of pure sodium tripolyphosphate (Fig 5a) showed characteristic
bands at 1218 (P O stretching) 1156 (symmetrical and asymmet
ric stretching vibration of the PO2 groups) 1094 (symmetric and
asymmetric stretching vibration of the PO3 groups) and 892 cm−1
(P O P asymmetric stretching) [25]
The main differences in the FTIR spectra of the particles related
to FTIR spectrum of raw CHT refers to the weak bands at 1250 cm−1
and 1218 cm−1 which can be assigned to P O stretching vibration
and the band at 892 cm−1 attributed to P O P asymmetric stretch
ing (Fig 5b–d) These signals indicate the presence of phosphate
groups in the CHTTPP particles [112526] The band at 1079 cm−1
attributed to stretching of C O bonds of primary alcohols (Fig 5e)
presented noticeable differences in comparison to the FTIR spec
tra of the particles (Fig 5b–d) These differences were mainly due
to complexation among CHT and TPP molecules [11] The band
at 1600 cm−1 that appears on CHT spectrum (Fig 5e) attributed
to N H deformation of amine groups is absent in the spectrum
of CHTTPP particles and a new band at 1523 cm−1 assigned to
+NH3 can be observed [1126] Therefore from this spectral infor
mation it can be concluded that the crosslinking was effective
through ionic interactions among negatively charged P O− moi
eties of the phosphate groups of TPP and protonated +NH3 moieties
of CHT chains The small differences in the FTIR spectra (range fromAF Martins et al International Journal of Biological Macromolecules 51 (2012) 1127– 1133 1131
Fig 4 Scheme depicting the physical crosslinking and selfassembly of CHT chains in CHTTPP2–3 and CHTTPP5–3 particles
Fig 5 FTIR spectrum of (a) TPP (b–d) CHTTPP particles and (e) CHT
2250 to 3750 cm−1) of the particles related to FTIR spectrum of CHT
were assigned to the diversities in the Hbonds intensities among
CHT–TPP and TPP–TPP chain segments However these spectral
differences were subtle since the Hbonds between the amino and
hydroxyl groups on the CHT chains also are extremely pronounced
as related in Section 311
32 Particles loading
321 Efficiency
The efficiency of HP loading was ca 99 for all samples (Table 3)
no important is the pH of solution used for loading neither the
CHTTPP ratio used during the particles preparation This means
that the natively charged HP would interact with remaining pos
itive sites on CHTTPP particles The efficiency of HP loading was
obtained according to methodology described by Martins et al [3]
Table 3
Heparin encapsulation efficiency for various particles compositions (n 2)
Particles Encapsulation efficiency ()
CHTTPP2–3 990
±
021
CHTTPP5–3 992
±
019
CHTTPP5–5 994
±
015
322 FTIR spectroscopy of HPloaded particles
The HPloaded CHTTPP particles (CHTTPP2–3HP CHTTPP5
3HP and CHTTPP55HP) were characterized by FTIR as presented
in Fig 6 It is possible to observe clear spectral changes due to
the incorporation of HP comparing the FTIR spectra of loaded and
unloaded CHTTPP2–3 particles (spectra i and a respectively Fig 6)
Firstly the enlargement of the band at 1238 cm−1 (Fig 6i) was
attributed to the axial deformation of S O groups from the saccha
ride structure of HP (Fig 6d) [3] Besides a broadening in the region
from 2500 cm−1 to 3500 cm−1 can be also verified It is worthy to
mention that at pH 2 the CHT chains present high density of pos
itive charges which strongly contributes to ionic association with
polyanions [327] This set of information confirms the HP encap
sulation and also suggests that at pH 2 there is stronger association
among HP chains and CHTTPP2–3 particles than at pH 5 probably
due to existing Hbonds and electrostatic interactions among +NH3
and OSO3
− groups This explains for instance the high efficiency
in loading the HP on CHTTPP particles
On the other hand the FTIR spectra for the loaded and unloaded
particles prepared at pH 5 did not show any important difference
The only variation to be mentioned is the increase in intensity of
the band at 2934 cm−1 attributed to the C H axial deformation
on HP [3] The bands at 1521 cm−1 and 1637 cm−1 showed some
variations in intensity however this fact was associated with the
weight of particles in the KBr pellets In light of this it is suggested
Fig 6 FTIR spectra of CHTTPP particles (a–c) CHTTPP particles with loaded HP
(i–iii) and HP (d)1132 AF Martins et al International Journal of Biological Macromolecules 51 (2012) 1127– 1133
Fig 7 TGA and DTG curves of the CHTTPP and CHTTPP particles with loaded HP
that HP is mainly adsorbed in the surface of obtained particles On
other hand the small differences in the FTIR spectra (Fig 6) were
mainly due to low weight proportion of HP on the loaded parti
cles when compared to the unloaded samples For each 10 g of
particle only 99 mg of HP were loaded Therefore the small differ
ences observed in the FTIR spectra (Fig 6) were attributed to the
HPloading process
323 Thermal stability of particles (TGADTG analysis)
The TGA curves from CHTTPP and CHTTPPHP particles are
presented Fig 7a It could be observed two thermal events of
weight loss in each curve The first one was attributed to the
loss of water and also of volatile compounds The CHTTPP2–3
CHTTPP5–3 and CHTTPP5–5 particles presented similar amounts
of adsorbed water ca 11 wt However the samples CHTTPP
showed different water content than CHTTPPHP ones The HP
incorporation decreased the water content of the samples This
fact was stronger in the CHTTPP2–3HP and CHTTPP5–3HP sam
ples The sulphonate groups ( OSO3
−) present in the HP structure
strongly interact to +NH3 groups from CHT decreasing the interac
tion (Hbond dipole–dipole and ion–dipole) intensity among water
molecules and CHT chains
The TGA profiles from the CHTTPP5–5 and CHTTPP5–5HP are
very similar mainly if the first thermal event is taken into account
This information correlates to those from WAXS profiles (Fig 3)
The non reorganization of CHT chains in the CHTTPP5–5 particles
indicates that the polysaccharide segments are not enough avail
able for interacting to water molecules as probably occurred in the
other samples
The first derivatives of degradation stage (second event on TGA
curves) for CHTTPP and CHTTPPHP are presented in Fig 7b It
is possible to observe that samples presented different degrada
tion temperatures as indicated by the inflexion points in the DTG
curves This fact reinforces the HP encapsulation The samples
CHTTPP2–3 CHTTPP5–3 and CHTTPP5–3 showed degradation
temperatures of 241 ◦C 251 ◦C and 248 ◦C respectively These dif
ferences were attributed mainly to the pH in which the particles
were prepared At low pH condition the TPP did not stabilize the
excess of +NH3 groups on CHT So there are domains in which
the electrostatic repulsion (see Fig 4) prevails contributing to less
packed structure which provides to CHTTPP2–3 lower thermal
stability compared to the other two samples
The adsorption of HP by the CHTTPP2–3 particles raises the
thermal stability in ca 6 ◦C from 241 ◦C to 247 ◦C This fact was
due to the further neutralization of remaining positive charges on
CHT by HP that also provides extra Hbonds allowing increasing the
thermal stability of CHTTPPHP2–3 sample
On the other hand the thermal stability of CHTTPP5–3
decreased from 251 ◦C to 244 ◦C due to the encapsulation of HP
(CHTTPP5–3HP) At pH 5 the presence of COO− and OSO3
− groups
on HP allows repulsion on composite material leading to a smaller
thermal stability compared to not HPloaded particles Finally it
Fig 8 Fraction of HP released from CHTTPP particles in distilled water (a) and in SGF (b)AF Martins et al International Journal of Biological Macromolecules 51 (2012) 1127– 1133 1133
can be seen that the incorporation of HP on CHTTPP5–5 parti
cles practically did not affect the thermal stability of the sample
(inflection point of TGA for CHTTPP5–5 occurs at 248 ◦C and for
CHTTPP5–5HP occurs at 249 ◦C)
As reported previously for each 10 g of particle only 99 mg of
HP were loaded Therefore the weight ratio particleHP is ca 1001
and TGADTG analyses were processed with only 60 mg of each
sample (CHTTPP loaded with HP and CHTTPP unloaded) Thus
the small differences observed in Fig 7 occur due to low weight
of HP on the CHTTPP loaded particles when compared to the
CHTTPP unloaded samples Thus the subtle differences observed
in the TGADTG curves also were assigned to the HPloading
process
33 In vitro release studies
The fractions of HP released from CHTTPP particles in distilled
water and in SGF are presented in Fig 8a and b respectively Consid
ering the CHTTPP5–3 particles it was verified that the maximum
fraction of HP released in distilled water was ca 17 and it is
achieved under 2 h (Fig 8a) after the test has been initiated This
result shows that CHTTPP5–3 particles present great potential to
be used as device for sustained release of HP at neutral pH and the
almost same condition found in intestinal region
The structureloosing was due to the lower amount of TPP the
crosslinking agent used for preparing the CHTTPP5–3 particles
and the pH close to 7 favored the HP releasing An opposite charac
teristic was found for CHTTPP2–3 This behavior can be understood
by the higher association of the drug (HP) to the CHTTPP parti
cles obtained at pH 2 as previously discussed The profile of HP
released in SGF is presented in Fig 8b The particles presented sta
bility in SGF and the extension of HP releasing was not as high as
was observed in distilled water Considering the CHTTPP5–5 par
ticles the maximum releasing was 5 in SGF for the first 1 h of
analysis
Following the same trend CHTTPP5–3 particles released only
25 of total loaded HP while in distilled water the fraction of HP
released was 17 Therefore the CHTTPP microparticles could be
successful used as sitespecific drug delivery of HP in the intestinal
region especially the CHTTPP5–3 particles
4 Conclusions
CHTTPP particles were successfully obtained from the
microemulsion method (WBnOH) at different CHTTPP ratios and
pH conditions The particles were characterized by SEM FTIR spec
troscopy and WAXS The morphology and crystallinity of particles
depend mainly on CHTTPP ratio The HP encapsulation was ca 99
for all tested samples as confirmed by TGA and FTIR techniques
Essays of controlled release of HP showed that CHTTPP particles
have high stability in SGF environment and in that condition the
releasing of HP was minimized On the other hand in distilled water
the CHTTPP5–3 particles released ca 17 (or 660 UI kg−1) of the
initially loaded HP Therefore CHTTPP5–3 particles could act as a
device for specific drug delivering of HP in the colon region This
study showed that the fraction of HP released could be tailored by
tuning the amount of TPP used in the particles preparation In light
of this lower CHTTPP ratios could improve the extension of HP
released from CHTTPP particles at pH 5
Acknowledgements
AFM and AGBP thank respectively to CNPq (Brazil) and to
CAPES (Brazil) for their doctorate fellowship AFR and ECM thank
to CNPq for the financial support
References
[1] JF Piai LC Lopes AR Fajardo AF Rubira EC Muniz Journal of Molecular
Liquids 156 (2010) 28–32
[2] SH Hua H Ma X Li H Yang A Wang International Journal of Biological
Macromolecules 46 (2010) 517–523
[3] AF Martins JF Piai ITA Schuquel AF Rubira EC Muniz Colloid and Polymer
Science 289 (2011) 1133–1144
[4] HT Ta H Han I Larson International Journal of Pharmaceutics 371 (2009)
134–141
[5] KH Bae CW Moon Y Lee TG Park Pharmaceutical Research 26 (2009)
93–100
[6] VK Mourya NN Inamdar Journal of Materials Science Materials in Medicine
20 (2009) 1057–1079
[7] AJM AlKarawi ZHJ AlQaisi HI Abdullah Carbohydrate Polymers 83 (2011)
495–500
[8] ST Lee FL Mi YJ Shen Polymer 42 (2001) 1879–1892
[9] LF Qi ZR Xu Colloids and Surfaces A 251 (2004) 183–190
[10] MK Sureshkumar D Das MB Mallia Journal of Hazardous Materials 184
(2010) 65–72
[11] FC Vasconcellos GAS Goulart MM Beppu Powder Technology 205 (2011)
65–70
[12] HK Stulzer MP Tagliari AL Parize MAS Silva MCM Laranjeira Materials
Science & Engineering CBiomimetic and Supramolecular Systems 29 (2009)
387–392
[13] L Zhang SL Kosaraju European Polymer Journal 43 (2007) 2956–2966
[14] AH Krauland MJ Alonso International Journal of Pharmaceutics 340 (2007)
134–142
[15] RHE Lecumberri A Heras Marine Drugs 8 (2010) 1750–1762
[16] G Agnelli Haemostasis 26 (1996) 2–9
[17] AF Martins AGB Pereira AR Fajardo AF Rubira MC Edvani Carbohydrate
Polymers 86 (2011) 1266–1272
[18] DK Kweon SB Song YY Park Biomaterials 24 (2003) 1595–1601
[19] AP Zhu Z Ming S Jian Applied Surface Science 241 (2005) 485–492
[20] AV Reis MR Guilherme AT Paulino EC Muniz LHC Mattoso EB Tam
bourgi Langmuir 25 (2009) 2473–2478
[21] RW Farndale DJ Buttle AJ Barrett Biochimica et Biophysica Acta 883 (1986)
173–177
[22] JF Piai AF Rubira EC Muniz Acta Biomaterialia 5 (2009) 2601–2609
[23] AR Fajardo JF Piai AF Rubira EC Muniz Carbohydrate Polymers 80 (2010)
934–943
[24] XZ Shu KJ Zhu European Journal of Pharmaceutics and Biopharmaceutics 54
(2002) 235–243
[25] FL Mi SS Shyu ST Lee TB Wong Journal of Polymer Science B 37 (1999)
1551–1564
[26] Y Luo B Zhang WH Cheng Q Wang Carbohydrate Polymers 82 (2010)
942–951
[27] S Boddohi CE Killingsworth MJ Kipper Biomacromolecules 9 (2008)
2021–2028

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