How sorbitan monostearate can increase drug-loading capacity of lipid-core polymeric nanocapsules

Article abstract of DOI:10.1166/jnn.2015.9182

Lipid-core polymeric nanocapsules are innovative devices that present distinguished characteristics due to the presence of sorbitan monostearate into the oily-core. This component acted as low-molecular-mass organic gelator for the oil (medium chain trigl

Full text of DOI:10.1166/jnn.2015.9182

Article
Journal of
Nanoscience and Nanotechnology
Vol. 15, 827–837, 2015
Copyright © 2015 American Scientific Publishers
All rights reserved
Printed in the United States of America
www.aspbs.com/jnn
How Sorbitan Monostearate Can Increase Drug-Loading
Capacity of Lipid-Core Polymeric Nanocapsules
1
ꢀ∗
2
3ꢀ†
Fernanda S. Poletto , Catiúscia P. de Oliveira , Heberton Wender ,
1
1
3
2
Dorothée Regent , Bruna Donida , Sérgio R. Teixeira , Sílvia S. Guterres ,
4
1ꢀ2
Bartira Rossi-Bergmann , and Adriana R. Pohlmann
1Departamento de Química Orgânica and Programa de Pós-Graduação em Química, Instituto de Química, Universidade Federal
do Rio Grande do Sul (UFRGS), P.BOX 15003, Porto Alegre, RS, CEP 91501-970, Brazil
2
Faculdade de Farmácia, Programa de Pós-Graduação em Ciências Farmacêuticas, Universidade Federal
do Rio Grande do Sul (UFRGS), Porto Alegre, RS, CEP 90610-000, Brazil
Instituto de Física, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS, CEP 91501-970, Brazil
3
4
Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro (UFRJ),
Rio de Janeiro RJ, CEP 21941-902, Brazil
Lipid-core polymeric nanocapsules are innovative devices that present distinguished characteristics
due to the presence of sorbitan monostearate into the oily-core. This component acted as low-
molecular-mass organic gelator for the oil (medium chain triglycerides). The organogel-structured
Delivered by Publishing Technology to: McMaster University
core influenced the polymeric wall characteristics disfavoring the formation of more stable poly-
IP: 110.87.30.92 On: Tue, 29 Dec 2015 09:56:03
mer crystallites. This probably occurred due to interpenetration of these pseudo-phases. Sorbitan
Copyright: American Scientific Publishers
monostearate dispersed in the oily-core was also able to interact by non-covalent bonding with the
drugs increasing the drug loading capacity more than 40 times compared to conventional nanocap-
sules. We demonstrated that the drug-models quercetin and quercetin pentaacetate stabilized the
organogel network probably due to interactions of the drug molecules with the sorbitan monos-
tearate headgroups by hydrogen bonding.
Keywords: Lipid-Core Nanocapsules, Sorbitan Monostearate, Organogel, Drug Loading,
Quercetin.
9
1
. INTRODUCTION
controlled drug release reducing the burst effect. As the
drug is dissolved in the oily-core, the drug permeability is
Polymeric nanocapsules are vesicular submicrometric
devices composed by an oily-core surrounded by a thin
polymeric wall and stabilized by surfactants and/or steric
agents. The core in nanocapsules acts as a reservoir for
the drug whereas the polymeric wall acts as a barrier
to the drug diffusion. The first reports about prepara-
tion and characterization of polymeric nanocapsules date
back to around 30 years ago. Since then, several stud-
ies concerning biomedical applications of those devices
1
0
strictly related to the characteristics of the polymeric wall.
Despite the important advantages of those devices their use
is limited by the maximum solubility of drug in the oil.
This drawback could be avoided by adding new com-
ponents into the oily-core that may work as a trap for
the drug molecules via non-covalent interactions. A higher
drug loading capacity is particularly important when
cellular uptake of nanocapsules is necessary for drug
1
2
ꢀ3
4
ꢀ5
1
1–13
1
ꢀ6ꢀ7
targeting.
Our group developed a new class of poly-
were reported with promising results.
The encapsu-
meric nanocapsules (called lipid-core nanocapsules) using
not only an oil but also sorbitan monostearate in the core.
Distinguished characteristics were observed for polymeric
nanocapsules when sorbitan monostearate was added to the
lated drugs may be protected from degradation caused
by storage or metabolism after administration and can be
passively or actively targeted to the site of action in the
8
organism. In addition, polymeric nanocapsules provide
1
4
formulation, such as higher rigidity, increasing physico-
1
5
∗
†
chemical stability under storage and protection of drugs
Author to whom correspondence should be addressed.
Present address: Departamento de Física, Universidade Federal de
from photodegradation. Recently,17 we described the
16
Mato Grosso do Sul, Campo Grande MS, CEP 79070-900, Brazil.
model of the formation mechanism for obtaining those
J. Nanosci. Nanotechnol. 2015, Vol. 15, No. 1
1533-4880/2015/15/827/011
doi:10.1166/jnn.2015.9182
827

How Sorbitan Monostearate Can Increase Drug-Loading Capacity of Lipid-Core Polymeric Nanocapsules
Poletto et al.
lipid-core nanocapsules and we demonstrated that the
nanocapsule number density of lipid-core nanocapsules
can be modulated leading to formulations with higher
(a)
OH
´
3
4´ OH
2
´
8
1´
B
HO
7
9
O
2
3
5´
1
8
total drug loading capacity. Slowing drug release kinetics
6
´
A
C
was also reported for lipid-core nanocapsules as func-
tion of increasing sorbitan monostearate concentrations.
The bulk mixture of the lipid-core components presented
non-Newtonian viscosity that was increased with higher
sorbitan monostearate concentrations. As a consequence,
the relative permeability of the drug was systematically
reduced because of its resistance to diffusion from the core
to the external medium.
6
10
OH
5
4
OH
O
(b)
O
O
3
´
4
´
O
O
One of our earlier studies about lipid-core nanocap-
sules19 evidenced that sorbitan monostearate was dis-
persed in the medium chain triglycerides of the lipid-core.
This was inferred because no melting peak from sorbi-
tan monostearate in lipid-core nanocapsules was detected
by differential scanning calorimetry whereas the melting
peak of this component appeared in the thermogram of
nanospheres (matrix systems). The differential scanning
calorimetry results as well as the drug release with con-
trolled kinetics described above for lipid-core nanocap-
sules suggest that sorbitan monostearate could be acting
as organogelator for medium chain triglycerides inside the
lipid-core. This hypothesis is supported by previous stud-
ies where sorbitan monostearate was shown to be low-
molecular-mass organic gelator for several hydrophobic
2´
1´
8
B
O
O
O
5´
7
9
2
6´
A
C
6
10
3
O
5
4
O
O
O
O
(
c)
OH
O
CH3
17
O
O
OH
Delivered by Publishing Technology to: McMaster University
HO
2
0
solvents including vegetable oils.
IP: 110.87.30.92 On: Tue, 29 Dec 2015 09:56:03
Considering those findings, we hyp Co toh pe ys ir zi ge dh t t: h Aa tm s eo rr ibc i a- n Scientific Publishers
tan monostearate is organized within the oily-core of the
nanocapsules establishing non-covalent interactions with
(d)
the drug molecules. As a result, the drug loading capacity
of lipid-core nanocapsules may be dramatically increased
relative to conventional formulations. In order to verify
this, we investigated how drug-models interacted with the
polymeric wall and the core of lipid-core and conven-
tional nanocapsules in order to describe the mechanism
whereby sorbitan monostearate can influence the drug
loading capacity. Quercetin and its pentaacetylated deriva-
tive (Fig. 1) where chosen as drug-models in this study
due to their high lipophilicity and capability to interact
with other molecules (such as the polymer and medium
chain triglycerides) by van der Waals forces and hydro-
gen bonding. While both drug molecules present hydrogen
bond acceptor groups, hydrogen bond donors are featured
only by the quercetin molecule. As a consequence, we
expected that each drug should interact differently with the
poly(ꢁ-caprolactone) wall and the core components.
O
O
O
O
H
O
O
O
H
5
2
2
5
n
n
Figure 1. Chemical structure of (a) quercetin, (b) quercetin pen-
taacetate, (c) sorbitan monostearate and (d) poly(ꢁ-caprolactone) ꢂ,ꢃ-
hydroxylated.
Caprylic/capric triglyceride was delivered from Alpha
Química (Porto Alegre, Brazil). Polysorbate 80 was
obtained from Gerbras (São Paulo, Brazil). Quercetin was
achieved from Henrifarma (São Paulo, Brazil). Acetic
anhydride (analytical grade) was distilled prior the syn-
thetic procedure. The other solvents were pharmaceutical,
analytical or chromatographic grade and were used with-
out further purification.
2
. MATERIALS AND METHODS
2
.1. Materials
2.2. Synthesis of Quercetin Pentaacetate
Poly(ꢁ-caprolactone) (PCL) (MW = 14,000; ꢂ,ꢃ-hydroxy-
lated) was supplied by Aldrich (Strasbourg, France). Sor-
bitan monostearate and 4-(N,N-dimethyl)aminopyridine
Quercetin pentaacetate was synthesized from quercetin
by
a
previously described procedure with slight
2
1
modifications. DMAP (0.44 mmol) was added to a solu-
tion of quercetin (3.3 mmol) in previously distilled acetic
(DMAP) were obtained from Sigma (St. Louis, USA).
8
28
J. Nanosci. Nanotechnol. 15, 827–837, 2015

Poletto et al.
How Sorbitan Monostearate Can Increase Drug-Loading Capacity of Lipid-Core Polymeric Nanocapsules
anhydride (25 ml) and the mixture was left under reflux
obscuration level of about 0.10. The background signal
was subtracted before each analysis. The mean diameter
over the volume distribution (d ꢅ and the diameter at 50%
ꢀ
(150 C) overnight. The reaction was followed by thin
layer chromatography. After 24 h, the warm mixture was
added to ice-water and filtered. The resulting precipitate
was dissolved in chloroform. This organic phase was 3×
4
ꢆ3
cumulative volume (d ꢅ were measured. In addition, the
0
ꢆ5
size distribution was obtained as the SPAN value (Eq. (1)).
extracted with 0.1 M NaHCO aqueous solution, dried
3
d0ꢆ9 −d
0ꢆ1
with anhydrous MgSO4 and purified by column chro-
matography (Silica gel 60, 70–230 mesh) using chloro-
form as eluent. The isolated product was obtained as
a yellow–white solid (73% of yield) presenting a melt-
Span =
(1)
d
0ꢆ5
where d0ꢆ9 and d0ꢆ1 are the diameters at 90% and 10%
cumulative volumes, respectively.
Formulations were also evaluated using ZetaSizer ZS
ꢀ
®
ing point of 194.9 C (Büchi Melting Point B-545
equipment). The product was assigned the structure of
−1
(
Malvern, UK) after dilution (10 ꢄl ml ꢅ in previously fil-
ꢁ
ꢁ
3
,3 ,4 ,5,7-pentaacetyl quercetin (Fig. 1) based on ATR-IR
®
tered (0.45 ꢄm) MilliQ water. Measurements were made
®
1
spectroscopy (Bruker Alpha-P equipment) and H-NMR
ꢀ
ꢀ
at an angle of 173 at 25 C. The autocorrelation function
was analyzed by the cumulant method and the CONTIN
algorithm. The cumulant method provided Z-average mean
size and polydispersity index (PI, Eq. (2))
®
analysis (Bruker equipment operating at 400 MHz) as
2
1
previously stated.
2
.3. Preparation of the Nanocapsules
ꢄ
2
2
The lipid-core nanocapsule formulations (LNC) were pre-
pared by interfacial deposition of preformed polymer as
PDI = ꢇ
(2)
2
2
previously described. Poly(ꢁ-caprolactone) (0.100 g),
capric/caprylic triglyceride (0.16 ml), sorbitan mono-
stearate (0.040 g) and drug (Table I) were dissolved in
where ꢇ and ꢄ represent the mean decay rate and its
2
variance, respectively. The CONTIN algorithm furnished
mean particle size and size distribution.
ꢀ
acetone (27 ml) at 40 C. This organic phase was injected
into an aqueous phase containing polysorbate 80 (0.080 g)
and water (53 ml) at 40 C under moderate stirring. After
2
.5. Nanoparticle Tracking Analysis (NTA)
ꢀ
Nanoparticle tracking analysis was performed with
a NanoSight LM10 (NanoSight, Amesbury, United
Kingdom), equipped with a sample chamber with a
1
0 min, acetone was elimi nD a et el idv ear ne dd tbh ye Ps uu sbp l ei sn hs ii no gn Tw ea cs hnology to: McMaster University
IP: 110.87.30.92 On: Tue, 29 Dec 2015 09:56:03
ꢀ
concentrated under reduced pressure at 40 C. The final
Copyright: American Scientific Publishers
volume was adjusted to 10 ml. Conventional nanocap-
sules (NC) were prepared as described for LNC but avoid-
ing sorbitan monostearate in the organic phase. Blank
nanocapsules (without drug) were also prepared for com-
parison. All formulations were made in triplicate.
6
40 nm laser. The formulations were diluted (10000×) in
®
previously filtered (0.45 ꢄm) MilliQ water and injected
in the sample chamber with glass syringe. The samples
were measured during 30 s using automatic shutter and
gain adjustments. The data were captured and analyzed
by NTA 2.2 Build 0380 software. Individual nanoparti-
cles moving under Brownian motion were identified and
tracked by the software. This movement was related to the
particle size according to a formula (Eq. (3)) derived from
the Stokes-Einstein equation,
2
.4. Particle Size Analysis
Nanocapsule suspensions were analyzed using a Malvern
Mastersizer® 2000 laser diffraction instrument (Malvern
Instruments, UK) in order to determine the presence of
micrometer populations. The formulations were added
into the dispersion device containing distilled water until
2
k T
B
2
ꢈxꢀyꢅ = 3
(3)
rhꢉꢊ
Table I. Composition of the poly(ꢁ-caprolactone) nanocapsule
formulations.
2
where kB is the Boltzmann constant and ꢈxꢀyꢅ is the
mean squared speed of a particle at a temperature T , in a
medium of viscosity ꢊ, with a hydrodynamic radius of
rh. The particle size distribution corresponded to the arith-
metic values calculated with the sizes of all the particles
analyzed by the equipment.
Quercetin
Quercetin
Sorbitan
Formulation (ꢄg ml 1ꢅ pentaacetate (ꢄg ml ꢅ monostearate (g ml
−
−1
−1
ꢅ
NC-blank
NC -Q
NC-P50
LNC-blank
LNC-Q25
LNC-Q40
LNC-Q65
–
40
–
–
–
50
–
–
–
–
–
–
10
40
–
0.004
0.004
0.004
0.004
0.004
0.004
0.004
2.6. Small Angle X-Ray Scattering (SAXS)
25
40
65
–
–
–
SAXS experiments were carried out at the D02A-SAXS2
beamline of the Brazilian Synchrotron Light Laboratory
(LNLS; Campinas, Brazil). The nanocapsule formulations
were placed into a sealed sample holder closed by two
mica windows and the scattering patterns were recorded
–
LNC-P35
35
50
75
LNC-P50
LNC-P75
J. Nanosci. Nanotechnol. 15, 827–837, 2015
829

How Sorbitan Monostearate Can Increase Drug-Loading Capacity of Lipid-Core Polymeric Nanocapsules
Poletto et al.
for 600 s under vacuum. The scattered intensity I(q) was
obtained from scattering vector q ranging from 0.284 to
microscope (Olympus BX41TF, Japan). Aliquots of the
nanocapsule formulations were evaluated at room tempera-
−
1
ꢀ
6
.886 nm . The scattering vector is defined as (Eq. (4))
ture, whereas the organogels were heated from 30 to 80 C
ꢀ −1
(
10 C min ꢅ by a hot-stage apparatus (Mettler Toledo
4
ꢉ ·senꢈ2ꢋꢅ
FP82HT). After this procedure, the samples were left to
reach the room temperature at a cooling rate of about
q =
(4)
ꢌ
ꢀ
−1
where ꢋ is the scattering angle, and ꢌ is the radiation
wavelength (0.1488 nm). The intensities were corrected for
the detector response and the dark current signal. Nanocap-
sule external medium (water) was subtracted from the for-
mulation data. Distributions of scattered intensity from 2D
SAXS images were converted to 1D using the software
10 C min (not controlled by the hot-stage apparatus).
2.10. Differential Scanning Calorimetry
The nanocapsules were dried under reduced pressure and
their residues were evaluated by differential scanning
calorimetry (DSC). Raw poly(ꢁ-caprolactone) without pre-
vious treatment was also evaluated for comparison. DSC
measurements were performed using a TA Instruments®
DSC Q20 (USA). Aluminum sealed pans were used with
sample weight of about 10 mg. The temperature scale was
established using indium as reference. Subambient tem-
peratures were reached using the instrument’s cooling sys-
tem to cool the DSC cell. Thermograms started with an
FIT2D. The Porod’s constant K was obtained from the
p
4
y intercept of I(q) × q as function of q fitting a linear
correlation2 for q range in the Porod’s regime.
3
2
.7. High Pressure Liquid Chromatograpy (HPLC)
In order to quantify quercetin and its pentaacetate deriva-
tive in the nanocapsules, the formulations were dissolved
®
ꢀ
in acetonitrile, filtered (0.45 ꢄm, Millipore ) and assayed
isotherm at −80 C over 5 min and then first and second
ꢀ
by high-performance liquid chromatography (HPLC). The
system consisted of a Perkin Elmer S-200 with injec-
tor S-200, detector UV-VIS, a guard-column and a col-
heating cycles were carried out from −80 to 100 C at a
ꢀ
−1
scanning rate of 10 C min . A cooling cycle was also
performed at the same temperature range and scanning rate
®
ꢀ
−1
umn (Merck LiChrospher 100 RP-18). The mobile phase
of −10 C min .
−1
(
0.8 ml min ꢅ consisted of methanol:water (70:30 v/v)
The thickness of the poly(ꢁ-caprolactone) crystalline
adjusted to apparent pH 2.7 with 1% (v/v) fosforic acid.
lamella L (nm) from the dried-residues of the nanocap-
c
Quercetin was detected at D3 6e 0l iv ne mr e dw ibt hy Pa ur be tl ei sn ht ii on ng Tt i me ce hnol os ug l ye sto w: Ma sc Mc a al cs ut el art eUd ni fvr eo rms it yt he maximum of the poly-
ꢀ
of 7.6 min, whereas quercetin pen It Pa a: c 1e 1t a0t e. 8 w7 .a 3s 0 d. e9 t 2e c Ot e nd : aTt ue, 2m 9e rD me ce l 2t i 0n g1 5c u0 r9v : e5 6T :03( C, first heating cycle) using the
m
Copyright: American Scientific Publishers
3
00 nm with a retention time of 11.6 min. Analytical stan-
Thomson-Gibbs relation (Eq. (5)),
dard curves of quercetin and its pentaacetylated derivative
ranged from 1 to 15 ꢄg ml . The analytical methods were
validated according to specificity, linearity and precision.
0
−1
2ꢍeT
m
L =
(5)
c
0
ꢎH ꢈT −T ꢅ
f
m
m
0
m
where ꢍ is the side surface energy, T is the equilibrium
e
2
.8. Preparation of the Organogels
melting temperature, Tm is the detected melting tempera-
Sorbitan monostearate (1.250 g) was dissolved in medium
chain triglycerides (5 ml) and acetone (12.5 ml) at 80 C.
The resulting solution maintained at 80 C during 1 h
3
temperature. An opaque, semisolid gel was obtained and
called ORGblank. To obtain gels containing drug, 12.5 ml
of an acetone solution of quercetin (1 mg ml ꢅ or its
pentacetyl derivative (1.25 mg ml ꢅ were added to the
sorbitan monostearate (1.250 g) and medium chain triglyc-
ture (determined by DSC), ꢎH is the melting enthalpy of
ꢀ
f
unit volume of poly(ꢁ-caprolactone) crystals. In this study,
ꢀ
the values of some variables were obtained from litera-
0 min and then was allowed to cool by standing at room
−
3
−2
ture as follows: ꢍ of Ref. [24] 40 ×10 J m , ꢎH of
e
6
f
−3
0
m
ꢀ
Ref. [25] 136×10 J m and T of Ref. [26] 78.9 C.
−
1
−1
3. RESULTS
The nanocapsules were obtained as bluish white liq-
uids and their particle size distribution was evaluated
by laser diffraction (Fig. 2). The formulations prepared
without drug presented only a submicrometric peak,
with d4ꢆ3 and d0ꢆ5 values of 0.263 ± 0.023 and 0.220 ±
ꢀ
erides (5 ml) mixture at 80 C. These gels containing
quercetin and quercetin pentaacetate were named ORGQ40
and ORGP50, respectively. Mixtures prepared as described
above avoiding sorbitan monostearate were also pre-
pared for comparison. These samples were called accord-
ing to their composition as CONTRblank, CONTRQ40 and
CONTRP50. The ORG and CONTR sample series were
maintained protected from light in desiccator until 1 week.
0
.027 ꢄm (NC-blank), and 0.220 ± 0.015 and 0.182 ±
0.017 ꢄm (LNC-blank), respectively. Both formulations
showed SPAN value of 1.8 ± 0.1. Drug-loaded lipid-core
nanocapsules were obtained adding increasing drug con-
centrations in the organic phase during the preparation pro-
cess. No micrometric population was visualized by laser
diffraction for lipid-core nanocapsules containing 25 and
2
.9. Optical Microscopy
Samples were placed onto clean glass slides and observed
under cross-polarized light illumination using an optical
−
1
40 ꢄg ml quercetin (LNC-Q25 and LNC-Q ꢅ as well
40
8
30
J. Nanosci. Nanotechnol. 15, 827–837, 2015

Poletto et al.
How Sorbitan Monostearate Can Increase Drug-Loading Capacity of Lipid-Core Polymeric Nanocapsules
comparison. A previous report demonstrated that nanopar-
ticle tracking analysis is able to detect the presence of drug
nanocrystals concomitantly to nanocapsules of similar
1
7
sizes due to variations in the scattering intensity values
for different colloidal structures. In this way, light scat-
tering intensity values were detected by the Nanosight®
camera and were plotted as function of the particle size
(Fig. 3). LNC-Q40 and LNC-P50 presented similar profiles
than LNC-blank, confirming that drug nanocrystals were
not formed in these formulations. Conversely, NC-Q40 and
NC-P50 showed higher scattering intensity values than that
of NC-blank, indicating the presence of nanocapsules and
Figure 2. Particle size distribution of (a) LNC-blank, (b) NC-blank,
also drug nanocrystals in these formulations.
(
c) LNC-Q , (d) LNC-Q , (e) LNC-Q , (f) NC-Q , (g) LNC-P ,
The formulations evaluated by the Nanosight® equip-
25
40
65
40
35
(
h) LNC-P , (i) LNC-P , (j) NC-P , by laser diffraction (average of
50
75
50
ment were also analyzed by dynamic light scattering at
three batches).
ꢀ
detection angle of 173 . The autocorrelation function was
treated using the cumulant method and the inverse Laplace
transform-based CONTIN algorithm. The mean size cal-
culated by the cumulant method varied from 200 nm (NC-
blank) to 218 nm (LNC-blank), with PDI lower than 0.2
−
1
as 35 and 50 ꢄg ml quercetin pentaacetate (LNC-P35
and LNC-P ꢅ. However, formulations containing 65 ꢄg
5
0
−
1
−1
ml quercetin (LNC-Q ꢅ and 75 ꢄg ml quercetin pen-
taacetate (LNC-P ꢅ showed micrometric population in
6
5
7
5
(Table II). CONTIN algorithm provided monomodal pop-
addition to the submicrometric peak. Lipid-core nanocap-
sules with no micrometer population presented close d4ꢆ3
and d0ꢆ5 values, which corresponded to 0.224± 0.003 and
ulations with mean sizes ranging from 223 nm (NC-blank)
to 249 nm (LNC-blank). Size distribution widths were
lower than 100 nm (Fig. 4).
0
.185± 0.010 ꢄm (LNC-Q ꢅ, 0.222± 0.022 and 0.186±
2
5
Quercetin and pentaacetylated quercetin encapsulated
in the lipid-core nanocapsules were quantified by high-
performance liquid chromatography (HPLC). Drug content
0
.023 ꢄm (LNC-Q ꢅ, 0.235± 0.023 and 0.196± 0.018 ꢄm
4
0
(
LNC-P ꢅ, 0.217 ± 0.009 and 0.182 ± 0.007 ꢄm (LNC-
35
Delivered by Publishing Technology to: McMaster University
P ꢅ. Their SPAN values were 1.9 ± 0.4, 1.8 ± 0.1, 1.8 ±
−1
40
−1
50
was 40.2± 3.0 ꢄg ml (LNC-Q ꢅ and 50.0± 2.5 ꢄg ml
IP: 110.87.30.92 On: Tue, 29 Dec 2015 09:56:03
0
.1 and 1.8 ± 0.1, respectively. Lipid-core nanocapsules
Copyright: American S (c Li eNn Ct i -f iPc 50 Pꢅ u, sb hl ios wh ien r gs that no drug was lost due to the prepa-
with micrometer population showed d and d values
4
ꢆ3
0ꢆ5
ration process of lipid-core nanocapsules. These drug con-
of 1.121 ± 0.461 and 0.198 ± 0.043 ꢄm (LNC-Q ꢅ and
40
6
5
tents corresponded to 13.2 ꢄmol (LNC-Q ꢅ and 9.7 ꢄmol
0
.363± 0.110 and 0.194± 0.060 ꢄm (LNC-P ꢅ, with SPAN
7
5
(
LNC-P ꢅ per gram of polymer.
50
values of 2.1 ± 0.1 (LNC-Q ꢅ and 2.1 ± 0.6 (LNC-P ꢅ.
6
5
75
The characteristics of interfaces in the nanocapsule for-
When sorbitan monostearate was avoided in the nanocap-
sule preparation (conventional nanocapsules), micromet-
ric and submicrometric populations were observed adding
mulations were investigated using synchrotron small-angle
X-ray scattering (SAXS). Scattering intensity I(q) for high
q values (q ꢂ L, where L is the characteristic length) can
inform about the interfaces of the sample without influ-
− −1
0 ꢄg ml quercetin (NC-Q ꢅ and 50 ꢄg ml quercetin
40
1
4
pentaacetate (NC-P ꢅ. Their d and d0ꢆ5 values were
23
5
0
4ꢆ3
ence of its form factor. In this way, the scattering data
0
0
0
.543± 0.164 and 0.283± 0.125 ꢄm (NC-Q ꢅ and 0.587±
4
4
4
0
were plotted as I(q)q versus q (Fig. 5) and fitted to a
straight line at q values obeying the Porod’s regime. The
.337 and 0.180± 0.011 ꢄm (NC-P ꢅ, with SPAN of 2.5±
5
0
.3 (NC-Q ꢅ and 2.4± 0.3 (NC-P ꢅ.
4
0
50
Porod constant (K ꢅ was obtained from the intercept of
p
The nanocapsule formulations were visualized by cross-
this straight line. The K value is related to the total scat-
p
polarized light microscopy. Birefringence was observed
only for LNC-Q , NC-Q , LNC-P and NC-P50 for-
tering surface area per unit volume (Sꢅ and to the volume
fraction of the phases (ꢎꢏ) (Eq. (6)).
6
5
40
75
mulations. The drugs previously dispersed in water also
presented birefringence. These results suggested that the
micrometer populations observed by laser diffraction in
the formulations were probably drug crystals. In order to
confirm this, nanoparticle tracking analysis was carried out
4
2
lim Iꢈqꢅq = K = 2ꢉꢈꢎꢏꢅ S
(6)
p
q→ꢃ
Conventional nanocapsules (without sorbitan monos-
−
2
tearate) showed Kp values of 5ꢆ61 × 10 (NC-blank),
®
−2
−2
for LNC-Q40 and LNC-P50 using the Nanosight equip-
4ꢆ30×10 (NC-Q ꢅ and 4ꢆ07×10 (NC-P ꢅ, whereas
40
50
−2
ment. These lipid-core formulations were chosen because
they showed the highest drug-content without being bire-
fringent by cross-polarized light microscopy. The drug-
loaded conventional nanocapsules NC-Q40 and NC-P50 as
well as the blank nanocapsules NC-blank and LNC-blank
were also evaluated by nanoparticle tracking analysis for
lipid-core nanocapsules presented K of 5ꢆ34 × 10
p
−
2
−2
(LNC-blank), 4ꢆ96 × 10
(LNC-Q ꢅ and 5ꢆ40 × 10
4
0
(LNC-P ꢅ.
5
0
To investigate the interactions between drugs and sor-
bitan monostearate dispersed in medium chain triglyc-
erides, we prepared bulk mixtures corresponding to the
J. Nanosci. Nanotechnol. 15, 827–837, 2015
831

How Sorbitan Monostearate Can Increase Drug-Loading Capacity of Lipid-Core Polymeric Nanocapsules
Poletto et al.
Delivered by Publishing Technology to: McMaster University
IP: 110.87.30.92 On: Tue, 29 Dec 2015 09:56:03
Copyright: American Scientific Publishers
Figure 3. Light scattering intensity detected by the Nanosight® camera (900 frames) as function of the particle size of the formulations (a) NC-blank,
b) LNC-blank, (c) NC-Q , (d) LNC-Q , (e) NC-P and (f) LNC-P , by nanoparticle tracking analysis. Particle size distribution as function of the
(
40
40
50
50
particle concentration is depicted in the detail.
lipid-core composition of LNC-blank (ORGblank), LNC-
Q40 (ORGQ40ꢅ and LNC-P50 (ORGP50ꢅ and characterized
them by cross-polarized optical microscopy equipped with
a hot stage. These mixtures were opaque, homogeneous
and presented gel-like consistency when observed with the
naked eye at room temperature. Conversely, these charac-
teristics were not observed for bulk mixtures correspond-
ing to NC-blank (CONTRblankꢅ, NC-Q40 (CONTRQ40ꢅ and
NC-P50 (CONTRP50ꢅ, where sorbitan monostearate was
missing. The organogels obtained using sorbitan monos-
tearate (ORG series) presented birefringence under cross-
polarized light illumination (Fig. 6). Mixtures without
sorbitan monostearate (CONTR series) were not birefrin-
gent excepting CONTRP50, which showed crystalline nee-
dle structures (Fig. 6, in the detail). The organogels were
Table II. Particle mean size and size distribution of the nanocapsule
formulations determined by dynamic light scattering (n = 3).
DLS (cumulant
method)
DLS (CONTIN
algorithm)
dh (Z-ave)
PI
dh
Distribution
Formulation
(nm)
(dimensionless)
(nm)
peak width (nm)
ꢀ
heated up to 80 C and changes in their microstructure
as function of temperature were monitored. The birefrin-
gent aggregates were disassembled (gel–sol transition) at
LNC-blank
NC-blank
218± 6
200± 6
203± 2
202± 2
208± 8
207± 10
0.11± 0.01
0.11± 0.01
0.12± 0.01
0.10± 0.02
0.08± 0.03
0.12± 0.01
249± 8
223± 8
231± 2
225± 11
230± 15
227± 11
88± 8
83± 5
86± 6
77± 10
74± 17
77± 6
ꢀ
ꢀ ꢀ
ꢅ, 51–54 C (ORG ꢅ and 49–53 C
Q40
LNC-Q40
49–51 C (ORG
blank
NC-Q40
LNC-P50
(
ORGP50ꢅ. Birefringent structures were formed (sol–gel
ꢀ
transition) with subsequent sample cooling to 46–47 C
(
NC-P50
ꢀ
ꢀ
ORGblankꢅ, 47–48 C (ORG ꢅ and 45–47 C (ORGP50ꢅ.
Q40
8
32
J. Nanosci. Nanotechnol. 15, 827–837, 2015

Poletto et al.
How Sorbitan Monostearate Can Increase Drug-Loading Capacity of Lipid-Core Polymeric Nanocapsules
(a)
(b)
1
00
1000
10000
100
1000
10000
10000
10000
Size (nm)
Size (nm)
(c)
(d)
100
1000
10000
100
1000
Size (nm)
Size (nm)
(
f)
(e)
Delivered by Publishing Technology to: McMaster University
IP: 110.87.30.92 On: Tue, 29 Dec 2015 09:56:03
Copyright: American Scientific Publishers
100
1000
10000
100
1000
Size (nm)
Size (nm)
Figure 4. Particle size distribution of (a) LNC-blank, (b) NC-blank, (c) LNC-Q , (d) NC-Q , (e) LNC-P , (f) NC-P , by dynamic light scattering
4
0
40
50
50
(
CONTIN algorithm).
The nanocapsules were dried under reduced pressure
observed for medium chain triglycerides, which T was
m
ꢀ
ꢀ
at room temperature and the remaining dried-residues
were analyzed by differential scanning calorimetry (DSC).
Poly(ꢁ-caprolactone) with no previous treatment was also
evaluated. It is known that poly(ꢁ-caprolactone) and
the caprylic/capric medium chain triglycerides present
reduced from −2 C (NC-blank) to −5 C (LNC-blank).
When drugs were added, the polymer Tm value of con-
ꢀ
40
ventional nanocapsules was decreased to 55 C (NC-Q ꢅ
ꢀ
or remained at 57 C (NC-P ꢅ, whereas was increased
to 56 C (LNC-Q ꢅ and 57 C (LNC-P ꢅ in lipid-core
5
0
ꢀ
ꢀ
4
0
50
ꢀ
27
melting temperatures typically of around 60
C
and
nanocapsules. The T value of medium chain triglycerides
m
ꢀ
19
0
C, respectively. Considering this, we identified first-
in conventional nanocapsules was not altered by the drugs
ꢀ
order transitions in the heating and cooling cycle ther-
mograms of the formulations that were assigned to
poly(ꢁ-caprolactone) from the polymeric wall and medium
chain triglycerides from the core (Fig. 7). The melt-
(−2 C for NC-Q , NC-P and NC-blank). Conversely,
4
0
50
drugs increased T of medium chain triglycerides in lipid-
m
ꢀ
ꢀ
core nanocapsules from −5 C to −2 C (LNC-Q and
4
0
LNC-P ꢅ.
5
0
ing temperature (T ꢅ of the polymer in the formulations
Crystallization temperature (T ꢅ of the polymer in con-
m
c
ꢀ
ꢀ
without drug was reduced from 57 C (NC-blank) to
ventional nanocapsules was decreased from 25 C (NC-
ꢀ
ꢀ ꢀ
blank) to 19 C (NC-Q ꢅ and 20 C (NC-P ꢅ in the
40 50
5
3 C (LNC-blank) in the first heating cycle due to the
presence of sorbitan monostearate. Similar behavior was
cooling cycle when drugs were added. On the other hand,
J. Nanosci. Nanotechnol. 15, 827–837, 2015
833

How Sorbitan Monostearate Can Increase Drug-Loading Capacity of Lipid-Core Polymeric Nanocapsules
Poletto et al.
ꢀ
ꢀ
ꢀ
0.45
0.40
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0.00
−
5 C (LNC-blank), −4 C (LNC-Q ꢅ and −3 C (LNC-
4
0
LNC-blank
LNC-Q40
P ) for lipid-core nanocapsules.
50
The first heating cycle gives information about the influ-
ence of the process of nanocapsule preparation on the ther-
mal properties of the samples. In this way, we used the
poly(ꢁ-caprolactone) melting temperatures from the first
heating to calculate the thickness of crystalline lamella
LNC-P50
(
L ꢅ of the polymer (Eq. (5)). These values were depen-
c
dent of the nanocapsule composition, varying from 8.0 nm
LNC-blank) to 9.4 (NC-blank, NC-P50 and NC-Q40ꢅ
(Table III).
(
0
500
1000
1500
2000
4
. DISCUSSION
q4 (nm–4
)
Nanocapsules and drug nanocrystals are simultaneously
0.45
0.40
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0.00
formed during the interfacial deposition of preformed
polymer when the formulation is saturated by drug.
NC-blank
NC-Q40
2
8
In order to investigate interactions among the drugs and
the pseudo-phases of the lipid-core nanocapsules with-
out interference of drug nanocrystals, we firstly deter-
mined their maximum drug loading capacity. Lipid-core
NC-P50
−
1
nanocapsules containing up to 40 ꢄg ml
and 50 ꢄg ml
quercetin
−
1
pentaacetylated quercetin presented
only a submicrometric monomodal particle size distribu-
tion by laser diffraction (Fig. 2) and no birefringence
by cross-polarized optical microscopy. When sorbitan
monostearate was avoided submicrometric and micromet-
Delivered by Publishing Technology to: McMaster University
ric populations were concomitantly formed in formula-
0
500
1000
1500
2000
IP: 110.87.30.92 On: Tue, 29 Dec 2015 09:56:03
tions containing 40 ꢄg ml quercetin and 50 ꢄg ml
Copyright: American Scientific Publishers
−1
−1
q4 (nm–4
)
pentaacetylated quercetin. These formulations showed
birefringence under cross-polarized light illumination, sug-
gesting that the micrometric populations observed by laser
diffraction could be drug aggregates. In fact, nanopar-
ticle tracking analysis demonstrated that light scattering
intensity was higher for NC-Q40 and NC-P50 than NC-
blank confirming that different colloidal structures were
concomitantly formed in those drug-loaded conventional
nanocapsules. On the other hand, light scattering inten-
sity detected by nanoparticle tracking analysis was similar
for LNC-blank, LNC-Q40 and LNC-P50 demonstrating that
drugs were entirely encapsulated in lipid-core nanocap-
sules. These results indicated the ability of sorbitan monos-
tearate to increase the drug saturation concentration of
lipid-core nanocapsules compared against conventional
nanocapsules. Drug nanocrystals presented similar mean
diameter than the nanocapsules, as indicated by the particle
concentration as function of size distribution obtained by
nanoparticle tracking analysis (Fig. 3). The nanocrystals
were aggregated forming micrometer structures after short
period and, as stated above, were detected as micrometric
peaks by laser diffraction and were visualized as birefrin-
gent structures using cross-polarized optical microscopy.
Similar mean diameters were found for conventional
nanocapsules and lipid-core nanocapsules by dynamic
light scattering, demonstrating that this parameter was not
affected by sorbitan monostearate. The experimental drug
Figure 5. Porod plot for SAXS data taken from the nanocapsule formu-
lations (hollow marker symbols of drug-loaded formulations were super-
imposed in both graphs).
ꢀ
drugs increased the polymer T from 18 C (LNC-blank)
c
ꢀ
to 20 C (LNC-Q and LNC-P ꢅ for lipid-core nanocap-
4
0
50
sules. Unresolved T peaks corresponding to medium chain
c
ꢀ
ꢀ
triglycerides were found at −44 C and −41 C for NC-
Q
and NC-P , respectively. These T values were lower
40
50
c
ꢀ
than that obtained for NC-blank (−33 C). When sor-
bitan monostearate was added, well resolved Tc peaks
ꢀ
from medium chain triglycerides were achieved at −34 C
ꢀ
(
LNC-blank and LNC-Q ꢅ and −33 C (LNC-P ꢅ.
4
0
50
We observed a double melting peak from the polymer
in all samples during the second heating cycle, indicating
segregation of the polymer crystalline phase that can be
associated with a secondary crystallization phenomenon.
In the presence of drugs the T values from the polymer in
m
ꢀ
conventional nanocapsules decreased from 49–53 C (NC-
blank) to 47–51 C (NC-Q ꢅ and 48–52 C (NC-P ꢅ. On
ꢀ
ꢀ
4
0
50
the other hand, drugs caused the opposite effect in lipid-
ꢀ
core nanocapsules increasing polymer Tm from 46–51 C
ꢀ ꢀ
LNC-blank) to 48–53 C (LNC-Q ꢅ and 49–53 C (LNC-
40
(
P ꢅ. The T value of medium chain triglycerides in the
5
0
m
ꢀ
second heating cycle was −3 C (NC-blank and NC-P ꢅ
5
0
ꢀ
and −4 C (NC-Q ꢅ for conventional nanocapsules and
4
0
8
34
J. Nanosci. Nanotechnol. 15, 827–837, 2015

Poletto et al.
How Sorbitan Monostearate Can Increase Drug-Loading Capacity of Lipid-Core Polymeric Nanocapsules
Figure 6. Microstructures of (a) ORGblank, (b) ORGQ40 and (c) ORGP50 observed under cross-polarized optical microscopy at room temperature.
Samples (a) CONTRblank, (b) CONTRQ40 and (c) CONTRP50 are depicted in the detail (bar = 50 ꢄm).
−
1
contents were 40.2 ꢄg ml for LNC-Q40 and 50.0 ꢄg
and ORGP50ꢅ were opaque with gel-like consistency. Their
birefringent aggregates observed at room temperature by
−
1
ml for LNC-P50 which corresponded to 100% encap-
sulation efficiency for bot hD ed rl iuv ge sr.e dC ob ny v eP r ut i bn lgi s hg ir na gm sT et oc hno loo pg t yi c at ol :m Mi ccr Mo s ac so tp ey r( UF ing i .v 6e )r sd i it sy assembled on heating due to
−
1
IP: 110.87.30.92 On: Tue, 29 Dec 2015 09:56:03
moles gives 0.132 ꢄmol ml quercetin and 0.097 ꢄmol
sorbitan monostearate melting. The gel state was restored
−
1
Copyright: American Scientific Publishers
ml quercetin pentaacetate. Therefore, more quercetin
molecules than quercetin pentaacetate molecules were nec-
essary to saturate the lipid-core nanocapsules.
In order to elucidate the reason for this, we investi-
gated the interactions among the drugs and the nanocap-
sule pseudo-phases in the formulations by SAXS and DSC.
Bulk mixtures of the lipid-core components were also
characterized. The Porod plot (Fig. 5) was taken from
when the samples were cooled to the room temperature
indicating thermal reversibility, as expected for organogels
3
1
obtained from low molecular-mass gelators. Mixtures
where sorbitan monostearate was missing (CONTR series)
were prepared for comparison. Birefringent structures were
not observed for CONTRQ40 indicating that quercetin was
dissolved in medium chain triglycerides. On the other
hand, quercetin pentaacetate was dispersed as birefrin-
gent crystal needles in CONTRP50 due to the low affin-
ity of this drug with the oil. It should be noted that
organogels containing quercetin (ORGQ40ꢅ and quercetin
pentaacetate (ORGP50ꢅ were not birefringent after melt-
ing regardless of the organogel melting temperatures (49
SAXS data and the Porod’s constant K was calculated for
high q range. The K values suggested that the S and/or
p
p
ꢎꢏ values of the conventional nanocapsules decreased due
to the drug-loading. On the other hand, these parameters
were not considerably affected by drugs when sorbitan
monostearate was present. This might be probably related
to the existence of the nanocrystal interfaces only in NC-
ꢀ
to 54 C) be much lower than those of drug melting
ꢀ
ꢀ
points (316 C for quercetin and 195 C for quercetin
3
2
Q40 and NC-P . Considering these results, we speculated
pentaacetate). This is evidence of the interaction between
sorbitan monostearate and the drug. The temperature at
which the organogels melted was increased from 49–
50
that drugs were molecularly dispersed in the lipid-core.
Previous studies demonstrated that sorbitan monos-
tearate can be structured as network of tubules when
dispersed in hydrophobic solvents such as vegetable
ꢀ
ꢀ ꢀ
ꢅ to 51–54 C (ORG ꢅ and 49–53 C
Q40
51 C (ORG
blank
(ORGP50ꢅ when drug was added to the mixture. We pro-
pose that the drug molecules interacted by hydrogen bond-
ing with sorbitan monostearate headgroups, which helped
to stabilize the organogel. Furthermore, ORGQ40 melted
at a higher temperature than that of ORGP50, demonstrat-
ing that the drug-sorbitan monostearate interaction was
stronger using quercetin than quercetin pentaacetate. Prob-
ably, this occurred because only the former drug presents
oils,20 hexadecane and isopropyl myristate. These
bulk mixtures presented high consistency and organogel
macroscopic feature. Then, we expected that sorbi-
tan monostearate would also act as low-molecular-mass
organic gelator for medium chain triglycerides. In fact,
we observed that the mixtures containing medium chain
triglycerides and sorbitan monostearate (ORGblank, ORGQ40
29
30
J. Nanosci. Nanotechnol. 15, 827–837, 2015
835

How Sorbitan Monostearate Can Increase Drug-Loading Capacity of Lipid-Core Polymeric Nanocapsules
Poletto et al.
Table III. Thermal properties of poly(ꢁ-caprolactone) and dried-
residues of nanocapsules (first heating cycle).
ꢀ
ꢀ
−1
Formulation Tm peak ( C) Tm onset ( C) ꢎH (J g ꢅ
L (nm)
c
NC-blank
LNC-blank
NC-Q40
LNC-Q40
NC-P50
57
53
55
56
57
57
53
47
53
53
53
53
65
98
78
78
87
74
9.4
8.0
8.7
9.0
9.4
9.4
LNC-P50
Notes: Tm = melting temperature; ꢎH = enthalpy of melting or dissolution; Lc
=
thickness of crystalline lamella (Thomson-Gibbs equation).
Sorbitan monostearate difficult the polymer nucleation in
the cooling cycle and reduced the polymer T in the sec-
m
ond heating cycle of the nanocapsules with no drug. The
polymer T shift from NC-blank to LNC-blank was higher
m
in first heating than second heating, indicating that the
size of the polymer crystallites not only was influenced
by the affinity between the components but also by the
process of nanocapsule preparation. Besides, heating and
cooling cycles of the nanocapsules with no drug demon-
strated that a thermoreversible interaction was established
between sorbitan monostearate and medium chain triglyc-
erides, similarly to the results described above for bulk
mixtures of these components using optical microscopy
with a hot stage apparatus.
Quercetin decreased Lc from 9.4 nm (NC-blank) to
Delivered by Publishing Technology to: McMaster University
8
.7 nm (NC-Q ꢅ in conventional nanocapsules whereas
40
IP: 110.87.30.92 On: Tue, 29 Dec 2015 09:56:03
this parameter was not altered by quercetin pentaac-
Copyright: American Scientific Publishers
etate (9.4 nm for NC-P ꢅ. Therefore, even than most of
5
0
quercetin was organized as nanocrystals in NC-Q40 a frac-
tion of drug was interacting with poly(ꢁ-caprolactone). On
the other hand, the polymeric wall in NC-P50 was not
affect by quercetin pentaacetate. Probably this difference
occurred because much more binding sites in the polymer
chains were able to interact more strongly with quercetin
than its pentaacetylated derivative due to the hydrogen
bond donating groups presenting only in the former drug
Figure 7. Differential scanning calorimetry curves at first heat-
ing (top), cooling (middle) and second heating (bottom) cycles of
(
a) poly(ꢁ-caprolactone) and dried-residues of (b) NC-blank, (c) LNC-
blank, (d) NC-Q , (e) LNC-Q , (f) NC-P and (g) LNC-P50.
40
40
50
(
Fig. 1). The T value of medium chain triglycerides was
m
similar in all conventional nanocapsules due to the low
affinity of drugs with the oil. This result confirmed the
very low drug-loading capacity showed by conventional
nanocapsules. In lipid-core nanocapsules, drugs shifted the
both hydrogen bond acceptors and donors in its molecular
structure providing more binding sites to be stabilized in
the sorbitan monostearate network.
The temperature shifts in first-order transitions from
dried-nanocapsule residues that were observed by DSC
furnished insights about the interactions among the
polymer Tm values at first heating, increasing L from
c
8
.7 nm to 9.0 nm (LNC-Q ꢅ and 9.4 nm (LNC-P ꢅ. This
40 50
suggested that drugs reduced the interpenetration of the
polymeric wall by sorbitan monostearate. We believe that
the stabilization of the sorbitan monostearate network pro-
vided by the drug molecules reduced the affinity between
the lipid-core and the polymeric wall. This is in agree-
ment with the cooling cycle results where drugs reduced
nanocapsule components. The T value of the polymer at
m
first heating cycle was reduced by sorbitan monostearate
in nanocapsules with no drug. We estimated L from the
c
Tm values of the polymer at first heating (Eq. (5)) and
observed that sorbitan monostearate decreased L from
c
9
.4 nm (NC-blank) to 8.0 nm (LNC-blank). In this way,
the polymer T value in conventional nanocapsules but
c
the lipid-core affected the characteristics of the poly-
meric wall disfavoring the formation of more stable poly-
mer crystallites. We inferred that the polymeric wall was
interpenetrated by the sorbitan monostearate molecules.
increased the polymer T value in lipid-core nanocapsules.
c
The polymer nucleation in the cooling cycle was promoted
by drugs only in the presence of sorbitan monostearate.
When this component was avoided in the formulation the
8
36
J. Nanosci. Nanotechnol. 15, 827–837, 2015

Poletto et al.
How Sorbitan Monostearate Can Increase Drug-Loading Capacity of Lipid-Core Polymeric Nanocapsules
polymer nucleation was difficult by drugs. Moreover, the
effect of drugs to reduce the affinity between sorbitan
monostearate and medium chain triglycerides was demon-
5. H. Fessi, F. Puisieux, J. P. Devissaguet, N. Ammoury, and S. Benita,
Int. J. Pharm. 55, R1 (1989).
6. P. Couvreur, G. Barratt, E. Fattal, P. Legrand, and C. Vauthier, Crit.
Rev. Ther. Drug Carrier Syst. 19, 99 (2002).
strated by the increased T values of medium chain triglyc-
m
7. V. Rosset, N. Ahmed, I. Zaanoun, B. Stella, H. Fessi, and
A. Elaissari, J. Colloid Sci. Biotechnol. 1, 218 (2012).
erides from drug-loaded lipid-core nanocapsules compared
to the T value from LNC-blank.
8. X. Rong, Y. Xie, X. Hao, T. Chen, Y. Wang, and Y. Liu, Curr. Drug
Discov. Technol. 8, 173 (2011).
m
9. R. V. Contri, M. Kaiser, F. S. Poletto, A. R. Pohlmann, and S. S.
5
. CONCLUSION
Guterres, J. Nanosci. Nanotechnol. 11, 2398 (2011).
1
1
0. I. Montasser, S. Briançon, and H. Fessi, Int. J. Pharm. 335, 176
2007).
The results demonstrated that sorbitan monostearate
altered the characteristics of the nanocapsule pseudo-
phases and significantly increased the drug loading
capacity of the formulations, which is a remark-
able technological advantage. As sorbitan monostearate
reduced the thickness of crystalline lamella from the
poly(ꢁ-caprolactone) wall, we believe that the polymeric
wall was interpenetrated by sorbitan monostearate. This
component was also a low-molecular-mass organic gela-
tor for medium chain triglycerides. In this way, lipid-core
nanocapsules can be defined as an organogel-structured
core surrounded by a polymeric wall. Quercetin and its
pentaacetyl derivative probably interacted with the sorbi-
tan monostearate headgroups by hydrogen bonding act-
ing as stabilizers for the organogel network within the
core. As a consequence, both drugs reduced the interaction
between the polymeric wall and the lipid-core that com-
pared to the blank lipid-core formulation. The stabiliza-
Delivered by Publishing Technology to: McMaster University
tion of the organogel network was stronger with quercetin,
which could explain the higher saturation concentration of
this drug in the lipid-core nanocapsules than that observed
for quercetin pentaacetate. In conclusion, we demonstrated
that drugs acting as stabilizers for sorbitan monostearate
network can be loaded in increased concentration by lipid-
core nanocapsules. This higher drug-loading capacity was
possible due to the innovative and complex supramolecular
organization of lipid-core nanocapsules.
(
1. F. S. Poletto, L. A. Fiel, M. V. Lopes, G. Schaab, A. M. O. Gomes,
S. S. Guterres, B. Rossi-Bergmann, and A. R. Pohlmann, J. Colloid
Sci. Biotechnol. 1, 89 (2012).
12. A. Laouini, C. Jaafar-Maalej, I. Limayem-Blouza, S. Sfar,
C. Charcosset, and H. Fessi, J. Colloid Sci. Biotechnol. 1, 147
(
2012).
1
3. T. Delmas, A. Fraichard, P.-A. Bayle, I. Texier, M. Bardet, J. Baudry,
J. Bibette, and A.-C. Couffin, J. Colloid Sci. Biotechnol. 1, 16
(
2012).
14. L. A. Fiel, L. M. Rebêlo, T. M. Santiago, M. D. Adorne, S. S.
Guterres, J. S. de Sousa, and A. R. Pohlmann, Soft Matter 7, 7240
(
2011).
1
5. A. F. Ourique, S. Azoubel, C. V. Ferreira, C. B. Silva, M. C.
Marchiori, A. R. Pohlmann, S. S. Guterres, and R. C. R. Beck,
J. Biomed. Nanotechnol. 6, 214 (2010).
16. V. Weiss, F. S. Poletto, L. R. Zancan, F. Baldasso, A. R. Pohlmann,
and S. S. Guterres, J. Biomed. Nanotechnol. 4, 80 (2008).
1
7. D. S. Jornada, L. A. Fiel, K. Bueno, J. F. Gerent, C. L. Petzhold,
R. C. R. Beck, S. S. Guterres, and A. R. Pohlmann, Soft Matter
8, 2646 (2012).
1
8. E. Jäger, C. G. Venturini, F. S. Poletto, L. M. Colomé, J. P.
IP: 110.87.30.92 On: Tue, 29 Dec 2015 09:56:03
U. Pohlmann, A. Bernardi, A. M. O. Battastini, S. S. Guterres, and
Copyright: American Scientific Publishers
A. R. Pohlmann, J. Biomed. Nanotechnol. 5, 130 (2009).
1
2
9. C. R. Muller, S. R. Schaffazick, A. R. Pohlmann, L. Lucca Freitas,
N. P. da Silveira, T. D. Costa, and S. S. Guterres, Die Pharmazie
56, 864 (2001).
0. S. Murdan, G. Gregoriadis, and A. T. Florence, J. Pharm. Sci.
88, 608 (1999).
21. A. Mattarei, L. Biasutto, F. Rastrelli, S. Garbisa, E. Marotta,
M. Zoratti, and C. Paradisi, Molecules 15, 4722 (2010).
2
2. C. G. Venturini, E. Jäger, C. P. Oliveira, A. Bernardi, A. M.
O. Battastini, S. S. Guterres, and A. R. Pohlmann, Colloids Surf. A
Acknowledgments: The authors thank to LNLS for
the access to D02A-SAXS2 beamline (proposal 10836).
Fernanda S. Poletto, Bruna Donida, Catiúscia P. de
Oliveira and Heberton Wender thank CAPES/MEC and
CNPq/MCTI for the fellowships. The authors thank the
financial support from Rede Nanobiotec CAPES, INCT-
if CNPq, PRONEM and PRONEX FAPERGS/CNPq,
PqG/FAPERGS and CNPq/Brazil.
375, 200 (2011).
2
2
3. O. Glatter and O. Kratky, Small Angle X-Ray Scattering, Academic
Press, London (1982).
4. P. Jarrett, C. V. Benedict, J. P. Bell, J. A. Cameron, and S. J. Huang,
Polymers as Biomaterials, Plenum Press, New York (1991).
5. Y. W. Cheung and R. S. Stein, Macromolecules 27, 2512 (1994).
6. C. Hsin-Lung, L. Lain-Jong, O. Y. Wen-Chung, C. H. Jenn, and
W. Wen-Young, Macromolecules 30, 1718 (1997).
2
2
27. D. Goldberg, J. Environ. Polym. Degrad. 3, 61 (1995).
2
8. A. R. Pohlmann, G. Mezzalira, C. G. Venturini, L. Cruz, A. Bernardi,
E. Jäger, A. M. O. Battastini, N. P. Da Silveira, and S. S. Guterres,
Int. J. Pharm. 359, 105 (2008).
29. S. Murdan, B. van den Bergh, G. Gregoriadis, and A. T. Florence,
J. Pharm. Sci. 88, 615 (1999).
30. S. Murdan, G. Gregoriadis, and A. T. Florence, Int. J. Pharm.
References and Notes
1
2
3
4
. C. E. Mora-Huertas, H. Fessi, and A. Elaissari, Int. J. Pharm.
385, 113 (2010).
. F. S. Poletto, E. Jäger, L. Cruz, A. R. Pohlmann, and S. S. Guterres,
Mat. Sci. Eng. C 28, 472 (2008)
. I. C. Kulkamp, K. Paese, S. S. Guterres, and A. R. Pohlmann, Quim
Nova 32, 2078 (2009).
. N. Al Khoury-Fallouh, L. Roblot-Treupel, H. Fessi, J. P.
Devissaguet, and F. Puisieux, Int. J. Pharm. 28, 125 (1986).
183, 47 (1999).
31. D. J. Abdallah and R. G. Weiss, J. Braz. Chem. Soc. 11, 209
(2000).
32. S. Rangaswami and K. Sambamurthy, Proc. Math. Sci. 46, 245
(1957).
Received: 2 July 2013. Accepted: 24 September 2013.
J. Nanosci. Nanotechnol. 15, 827–837, 2015
837