Poly(lactic acid) scaffolds modified by gelatin for the controlled release of tetrandrine in vitro
To mimic natural extracellular matrix architecture, tetrandrine-loaded poly(L-lactic acid) scaffolds modified by gelatin were prepared via phase separation, solvent replacement and freeze-drying. The purpose of this work was to combine the biological effects of tetrandrine and the advantages of poly...
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НТК «Інститут монокристалів» НАН України
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| Цитувати: | Poly(lactic acid) scaffolds modified by gelatin for the controlled release of tetrandrine in vitro / Zhang Ye // Functional Materials. — 2017. — Т. 24, № 4. — С. 660-666. — Бібліогр.: 34 назв. — англ. |
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nasplib_isofts_kiev_ua-123456789-1368912025-02-10T01:18:54Z Poly(lactic acid) scaffolds modified by gelatin for the controlled release of tetrandrine in vitro Zhang Ye Technology To mimic natural extracellular matrix architecture, tetrandrine-loaded poly(L-lactic acid) scaffolds modified by gelatin were prepared via phase separation, solvent replacement and freeze-drying. The purpose of this work was to combine the biological effects of tetrandrine and the advantages of poly(L-lactic acid) scaffolds which was modified by gelatin to enhancing the mass transfer features of controlled release systems. Tetrandrine contained in the scaffolds was confirmed by X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared (FT-IR) spectroscopy. Tetrandrine did not change the morphous, crystallinity and thermodynamics of the scaffolds which demonstrated by differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and X-ray powder diffractometry (XRD). The results of this study showed a sustained release with 79.15% for 188 days in vitro. 2017 Article Poly(lactic acid) scaffolds modified by gelatin for the controlled release of tetrandrine in vitro / Zhang Ye // Functional Materials. — 2017. — Т. 24, № 4. — С. 660-666. — Бібліогр.: 34 назв. — англ. 1027-5495 DOI: https://doi.org/10.15407/fm24.04.660 https://nasplib.isofts.kiev.ua/handle/123456789/136891 en Functional Materials application/pdf НТК «Інститут монокристалів» НАН України |
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Technology Technology Zhang Ye Poly(lactic acid) scaffolds modified by gelatin for the controlled release of tetrandrine in vitro Functional Materials |
| description |
To mimic natural extracellular matrix architecture, tetrandrine-loaded poly(L-lactic acid) scaffolds modified by gelatin were prepared via phase separation, solvent replacement and freeze-drying. The purpose of this work was to combine the biological effects of tetrandrine and the advantages of poly(L-lactic acid) scaffolds which was modified by gelatin to enhancing the mass transfer features of controlled release systems. Tetrandrine contained in the scaffolds was confirmed by X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared (FT-IR) spectroscopy. Tetrandrine did not change the morphous, crystallinity and thermodynamics of the scaffolds which demonstrated by differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and X-ray powder diffractometry (XRD). The results of this study showed a sustained release with 79.15% for 188 days in vitro. |
| format |
Article |
| author |
Zhang Ye |
| author_facet |
Zhang Ye |
| author_sort |
Zhang Ye |
| title |
Poly(lactic acid) scaffolds modified by gelatin for the controlled release of tetrandrine in vitro |
| title_short |
Poly(lactic acid) scaffolds modified by gelatin for the controlled release of tetrandrine in vitro |
| title_full |
Poly(lactic acid) scaffolds modified by gelatin for the controlled release of tetrandrine in vitro |
| title_fullStr |
Poly(lactic acid) scaffolds modified by gelatin for the controlled release of tetrandrine in vitro |
| title_full_unstemmed |
Poly(lactic acid) scaffolds modified by gelatin for the controlled release of tetrandrine in vitro |
| title_sort |
poly(lactic acid) scaffolds modified by gelatin for the controlled release of tetrandrine in vitro |
| publisher |
НТК «Інститут монокристалів» НАН України |
| publishDate |
2017 |
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Technology |
| url |
https://nasplib.isofts.kiev.ua/handle/123456789/136891 |
| citation_txt |
Poly(lactic acid) scaffolds modified by gelatin for the controlled release of tetrandrine in vitro / Zhang Ye // Functional Materials. — 2017. — Т. 24, № 4. — С. 660-666. — Бібліогр.: 34 назв. — англ. |
| series |
Functional Materials |
| work_keys_str_mv |
AT zhangye polylacticacidscaffoldsmodifiedbygelatinforthecontrolledreleaseoftetrandrineinvitro |
| first_indexed |
2025-12-02T10:56:05Z |
| last_indexed |
2025-12-02T10:56:05Z |
| _version_ |
1850393719117709312 |
| fulltext |
660 Functional materials, 24, 4, 2017
ISSN 1027-5495. Functional Materials, 24, No.4 (2017), p. 660-666
doi:https://doi.org/10.15407/fm24.04.660 © 2017 — STC “Institute for Single Crystals”
Poly(lactic acid) scaffolds modified by gelatin for
the controlled release of tetrandrine in vitro
Zhang Ye1,2
1 Department of Pharmaceutical Sciences, Zibo Vocational Institute,
Zibo, Shandong 255314, China
2 Research Center of Traditional Chinese Medicine,
Tianjin University of Traditional Chinese Medicine, Tianjin300193, China
Received August 20, 2017
To mimic natural extracellular matrix architecture, tetrandrine-loaded poly(L-lactic acid)
scaffolds modified by gelatin were prepared via phase separation, solvent replacement and
freeze-drying. The purpose of this work was to combine the biological effects of tetrandrine and
the advantages of poly(L-lactic acid) scaffolds which was modified by gelatin to enhancing the
mass transfer features of controlled release systems. Tetrandrine contained in the scaffolds was
confirmed by X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared (FT-IR)
spectroscopy. Tetrandrine did not change the morphous, crystallinity and thermodynamics of
the scaffolds which demonstrated by differential scanning calorimetry (DSC), scanning electron
microscopy (SEM) and X-ray powder diffractometry (XRD). The results of this study showed a
sustained release with 79.15% for 188 days in vitro.
Keywords: poly(lactic acid) scaffolds, gelatin, tetrandrine, tissue engineering.
С целью воссоздания естественной архитектуры внутриклеточного матрикса методами
разделения фаз, заменой растворителя и сублимационной сушки были синтезированы
полимерные каркасы поли(L-молочной кислоты), модифицированные желатином и
загруженные тетрандрином. Цель данной работы состояла в объединении биологического
эффекта тетрандрина и преимуществ синтезированных каркасов для повышения
характеристик массопереноса с контролируемым высвобождением лекарственного вещества
(тетрандрина). Присутствие тетрандрина в синтезированных каркасах определялось
методами рентгеновской фотоэлектронной спектроскопии и инфракрасной спектроскопии
с Фурье-преобразованием. Методами дифференциально сканирующей калориметрии,
сканирующей электронной микроскопии и рентгенфазового анализа показано, что
тетрандрин не изменяет морфологию, кристалличность и термодинамику образования
каркасов. Результаты исследования in vitro показали, что синтезированные каркасы
обеспечивают пролонгированное высвобождение 79,15% тетрандрина в течение 188 дней.
Полімерні каркаси полі (L-молочної кислоти), модифіковані желатином для
контрольованого вивільнення тетрандріна in vitro. Zhang Ye
З метою відтворення природної архітектури внутрішньоклітинного матриксу методами
розподілу фаз, заміною розчинника та сублімаційною сушкою були синтезовані полімерні
каркаси полі (L-молочної кислоти), модифіковані желатином і завантажені тетрандріном.
Мета даної роботи полягала в об’єднанні біологічного ефекту тетрандріна і переваг
синтезованих каркасів для підвищення характеристик масопереносу з контрольованим
вивільненням лікарської речовини (тетрандріна). Присутність тетрандріна в синтезованих
каркасах визначався методами рентгенівської фотоелектронної спектроскопії та
інфрачервоної спектроскопії з Фур’є-перетворенням. Методами диференційно скануючої
калориметрії, скануючої електронної мікроскопії та рентген-фазового аналізу показано,
що тетрандрін не змінює морфологію, кристалічність і термодинаміку створення каркасів.
Результати дослідження in vitro показали, що синтезовані каркаси забезпечують
пролонговане вивільнення 79,15% тетрандріна протягом 188 днів.
Functional materials, 24, 34 2017 661
Zhang Ye / Poly(lactic acid) scaffolds modified by ...
1. Introduction
Much interest has been generated recently
in the area of tissue engineering to create bio-
logical alternatives for implants and prosthe-
ses. In this approach, a highly porous scaffold
(artifical extracellular matrix) is needed to ac-
commodate cells and guide their growth and
tissue regeneration in three dimensions. Biode-
gradable polymers, either natural or synthetic,
have been processes into scaffolds for tissue en-
gineering [14]. Poly(lactic acid) (PLLA), a biode-
gradable synthetic materials, was widely used
in biomedical engineering due to their innocu-
ity, biodegradability, bioenvironmental com-
patibility and so on [14, 25, 6]. It was therefore
approved by the Food and Drug Administration
(FDA) for certain human clinical applications
such as surgical sutures and some implantable
devices. Recently, porous PLLA scaffolds were
widely investigated in osteoblastic [32], cranial
bone [22] , corneal [1], chondrocyte [2] tissue
engineering, etc. However, one disadvantage of
PLLA scaffold was the complications resulting
from the accumulation of lactic acid produced
in the process of degradation.
Growth factor is mostly water soluble pro-
tein from human or animal. Its price is expen-
sive, and its biological property is unstable.
Thus, its loading on the scaffolds has certain
difficulty. Additionally, excessive dose of growth
factor may induce tumor cell growth. Antibiot-
ics are also used in engineering scaffolds for
antibacterial and anti-infection in vitro [12].
However, the pharmacological action of anti-
biotics is only simple antibacterial. Antibiotics
have no physiological activity. Some effective
components in traditional Chinese medicine
has a function similar to that of the cytokines
and the corresponding pharmacological effects,
and the price is low, the physical and chemical
properties is relative stability. Thus, they show
good prospects for application as substitutes of
cytokines. Tetrandrine (Tet), a bis-benzyliso-
quinoline alkaloid isolated from the dried root
of the natural Chinese herb Stephania tetran-
dra which used as an effective agent for rheu-
matic arthritis and rheumatoid arthritis exhib-
its a variety of pharmacological activities such
as anti-inflammatory, antioxidant, anti-fibrotic
and anticancer activities, antiplatelet aggrega-
tion, Ca2+ channel block, immunosuppressive,
and free radical scavenging effects [11, 13, 17,
23, 24, 30]. Consequently, it has effective func-
tion in the treatment of many diseases includ-
ing pulmonary diseases, hepatic fibrosis, ar-
thritis, silicosis and so on [9,10,16, 20]. Tet has
also shown antidepressant-like effect by regu-
lating the central monoaminergic neurotrans-
mitter system and the levels of BDNF [7] . Ac-
cording to previous literature, low concentra-
tion of Tet (1-2.5 mg/L) promotes proliferation,
activity and glycosaminoglycan and collagen-
secreting of chondrocyte. Thus, Tet has great
prospective future in cartilaginous tissue en-
gineering applications [5]. Compared with con-
trol PLLA films, Tet loaded in the poly (L-lactic
acid) (PLLA) films could reduce the inflamma-
tory response in macrophages by regulating
the mRNA expression and protein expression,
and significantly inhibit inflammatory reaction
in 4, 12 weeks after implanting in rats. There-
fore, Tet could enhanced the biocompatibility of
PLLA films [21].
The purpose of the present work was to pre-
pare Tet-loaded PLLA scaffolds modified by
gelatin and investigate the controlled release
of tetrandrine in vitro. PLLA scaffolds modi-
fied by gelatin, as biomimetic surface modifier
could elicit controlled cellular adhesion and
maintain differentiated phenotypic expres-
sion [4], were prepared via phase separation,
solvent replacement, freeze-drying. Then, Tet
which presents anti-inflammatory activities
and physiological activities similar to cytokine
was loaded on PLLA scaffolds modified. Alka-
lescence and anti-inflammatory activities of
Tet could relieve complications resulting from
the accumulation of lactic acid produced in the
process of degradation. The drug with specific
properties could be sustained delivered to the
necessary site of action, and thus repair recon-
stituted cartilage tissue and maintain its phe-
notype and cellular function. X-ray photoelec-
tron spectroscopy (XPS) and Fourier-transform
infrared (FT-IR) spectroscopy were measured
to evaluate the formulation of modified PLLA
scaffolds and Tet-loaded PLLA scaffolds. Dif-
ferential scanning calorimetry (DSC), scanning
electron microscopy (SEM) and X-ray powder
diffractometry (XRD) were performed to com-
pare the physicochemical properties. On the
other hand, drug content and release behaviors
were performed to evaluate sustained release
characteristics of Tet-loaded PLLA scaffolds.
2. Materials and methods
2.1 Materials
Poly(L-lactic acid) (PLLA, Mn=4.32×104 g/mol)
was kindly donated by Prof. Xue-Si Chen,
Changchun Institute of Applied Chemistry
Chinese Academy of Sciences. Tetrandrine
(Tet) and gelatin were purchased from Sigma-
Aldrich Co. (St Louis, USA). HPLC grade aceto-
nitrile were supplied by Merck & Co., Inc. (Bei-
jing, China). Other materials and solvents used
were of analytical reagent grade.
662 Functional materials, 24, 4, 2017
Zhang Ye / Poly(lactic acid) scaffolds modified by ...
2.2 Preparation of PLLA scaffolds
On the basis of the theory of thermally in-
duced phase separation (TIPS) and freeze-dry-
ing approach (FDA) [15,18,29,31], three-dimen-
sional microporous PLLA scaffolds modified
by gelatin were fabricated via phase separa-
tion, solvent replacement and freeze-drying. A
typical procedure was used as following: pre-
weighed PLLA was dissolved in tetrahydrofu-
ran (THF) at 60°C to form 5% (wt/v, polymer/
THF) solution. The solution was poured into
glass vials, which were then quickly put into
-80°C refrigerator for 24 hours to gel. The vials
containing the PLLA solution was then trans-
ferred into 50% (v/v) ethanol at -20°C. After 24
hours for solvent exchange, the ethanol was re-
placed with 5 wt % gelatin aqueous solution for
16 hours at room temperature. Then, the gel
was placed in distilled water for 2 day, exchang-
ing with fresh distilled water three times a day,
and then put into -20°C refrigerator again for
freezing. Afterwards, the frozen gel lyophilized
in a freeze-drier for the purpose of removing
water sufficiently and the PLLA scaffolds were
acquired accordingly.
The fabrication of Tet-loaded PLLA scaf-
folds was slightly different from that of PLLA
scaffolds. One needs to add 10% Tet (wt/wt,
Tet/polymer) in 5% (wt/v, polymer/THF) poly-
mer solution before pouring into glass vials. All
other processes were identical.
2.3 Characterization of PLLA scaffolds
XPS measurements of PLLA scaffolds,
modified PLLA scaffolds and Tet-loaded PLLA
scaffolds were performed on a instrument (Per-
kin Elmer 5600, USA) with Al Kα radiation
(hv=1486.6 eV). The values of binding energies
were calibrated with respect to C1s peak at
284.7 eV.
FT-IR spectra of PLLA scaffolds modified
PLLA scaffolds and Tet-loaded PLLA scaffolds
were recorded on an infrared spectrometer
(BIO-RAD FTS3000, USA). The samples were
prepared by the potassium bromide disc meth-
od and scanned for absorbance 4000-400 cm−1.
The powder X-ray diffraction patterns of
modified PLLA scaffolds and Tet-loaded PLLA
scaffolds were recorded using an X-ray diffrac-
tometer (Rigaku D/max-2500, Japan). Radia-
tions generated from Cu Kα source and filtered
through Ni filters with a wavelength of 0.154
nm at 20 mA and 36 kV were used. The scan-
ning rate employed was 4°/min over the 10-40°
range.
DSC thermograms of scaffolds were record-
ed on a differential scanning calorimeter (PER-
KIN-ELMER DSC 7, USA). The instrument
was calibrated with indium and zinc prior to
analyzing the samples under nitrogen. All ac-
curately weighed samples (2.5 mg) were placed
into sealed aluminium pans and scanned at the
heating rate of 10 °C/min over the temperature
range of 30-250 °C.
Scaffolds were viewed with a scanning elec-
tron microscope (SEM, Philips XL30, Nether-
lands). The surface and inner microstructures
were investigated on specimen surfaces and
cross-sections cut in liquid nitrogen. The sam-
ples were coated with gold prior to SEM obser-
vation.
2.4 Determination of Tet release behaviors
Pre weighed amounts of PLLA scaffolds were
suspended in 50 mL of PBS (pH 7.4) buffer solu-
tion at 37°C. At predetermined time intervals,
200 μL of released solution was withdrawn for
measuring, which was replenished by 200 μL
of fresh PBS solution to maintain a constant
volume. The concentration of released Tet was
monitored on a Waters 2695 series HPLC sys-
tem. 20-microliter samples were injected on a
reversed-phase HPLC column (Thermo C18,
250 mm´4.6 mm, 5 μm). The mobile phase con-
sisted of a mixture of acetonitrile and water at
30:70 containing 0.12% (v/v) diethylamine and
pH value was modified at 4 by phosphoric acid
(H3PO4). Flow rate was adjusted to 1.0 mL/min.
All samples were analyzed in triplicate at 282
nm. The average and standard deviations were
presented.
3. Results and discussion
3.1 XPS
XPS is a quantitative spectroscopic tech-
nique that measures the elemental composi-
tion, empirical formula, chemical state and
electronic state of the elements that exist with-
in a material. XPS spectra are obtained by irra-
diating a material with a beam of X-rays while
simultaneously measuring the kinetic energy
(KE) and number of electrons that escape from
the top 1 to 10 nm of the material being ana-
lyzed. A typical XPS spectrum is a plot of the
number of electrons detected (sometimes per
unit time) (Y-axis, ordinate) versus the binding
energy of the electrons detected (X-axis, abscis-
sa). Each element produces a characteristic set
of XPS peaks at characteristic binding energy
values that directly identify each element that
exist in or on the surface of the material being
analyzed.
The XPS spectrum of scaffolds was shown in
Figure 1. As can be discovered, PLLA scaffolds
showed two XPS peaks at 284.7 eV and 532.8
eV which assigned to C1s and O1s respectively.
By contrast, modified PLLA scaffolds displayed
a new XPS peaks at 399.5 eV which attributed
to N1s due to cyano (-CONH) or amine (-NH2 )
Functional materials, 24, 34 2017 663
Zhang Ye / Poly(lactic acid) scaffolds modified by ...
groups of gelatin. Therefore, gelatin was con-
tained on the surface of PLLA scaffolds. As ex-
pected, the surface nitrogen content is larger for
Tet-loaded PLLA scaffolds, compared to PLLA
scaffolds modified by gelatin (Table 1). This
result can be attributed to nitrogen of tertiary
amines contained in Tet. In this case, Tet was
contained on the surface of PLLA scaffolds.
3.2 FT-IR spectroscopy
FT-IR spectroscopy was utilized as anoth-
er supporting evidence for the formulation of
modified PLLA scaffolds and Tet-loaded PLLA
scaffolds. FT-IR spectrograms of samples were
given in Fig. 2. The hydroxyl (-OH), amino (-
NH2) and cyano (-CONH2) groups gelatin
stretching bands at 3000-3700 cm–1 (as the ar-
row in the Figure 3 shown) , as well as C=O
gelatin stretching bands at 1651 cm–1 and
amino gelatin characteristic absorption bands
at 1557 cm–1 appeared in the FT-IR spectro-
gram of modified PLLA scaffolds. These were
evidence of gelatin contained on the surface of
modified PLLA scaffolds.
In comparison to the FT-IR spectrum of
modified PLLA scaffolds, Tet-loaded PLLA
scaffolds exhibits little changes in shapes,
while the strength and width of characteristic
absorption bands increased due to approxi-
mately the superposition of Tet and modified
PLLA scaffolds.
3.3 XRD
According to previous reports, modified
PLLA scaffolds were conducive to cell adhe-
sion, proliferation and function, so it has bright
future in tissue engineering [3,4,33]. With the
aim to confirm the potentiality of Tet-loaded
PLLA scaffolds in chondrocyte tissue engi-
neering, XRD was measured. XRD clearly
confirmed the crystalline nature of Tet as
well as the amorphous state of PLLA scaffolds
(Figure 3). The crystalline peaks of modified
PLLA scaffolds that at 2θ are equal to 16.6°
and 19.1° which in accordance with the conclu-
sion previous reported by Hideto Tsuji [19].
These peaks are comparable with α form of
PLLA crystallized in a pseudo-orthorhombic
unit cell of dimensions: a = 1.07 nm, b = 0.595
nm and c = 2.78 nm which contains two 103 he-
lices. It was worth noting that the shape of Tet-
loaded scaffolds observed on diffractograms
showed no significant differences from that of
modified PLLA scaffolds. Therefore, the load-
ing of Tet did not change the crystallinity of the
scaffolds.
3.4 DSC
DSC thermograms of modified PLLA scaf-
folds and Tet-loaded PLLA scaffolds were re-
ported in Figure 4, and the melting temperature
(Tpeak) and fusion enthalpy (ΔH) were listed in
Table 2. As can be discovered, the thermogram of
modified PLLA scaffolds showed a fusion endo-
Fig 1. The XPS spectrum of PLLA scaffolds (a),
modified PLLA scaffolds (b) and Tet-loaded
PLLA scaffolds (c).
Fig. 2. FT-IR spectrum of Tet (a), PLLA scaffolds
(b), modified PLLA scaffolds (c) and Tet-loaded
PLLA scaffolds (d).
Table 1. The elements composition of PLLA scaffolds (a), modified PLLA scaffolds (b) and Tet-loaded
PLLA scaffolds (c)
Samples element composition (%)
C O N
PLLA scaffolds 65.6 34.4 0
modified PLLA scaffolds 63.2 33.6 3.1
Tet-loaded PLLA scaffolds 63.6 32.5 3.8
664 Functional materials, 24, 4, 2017
Zhang Ye / Poly(lactic acid) scaffolds modified by ...
thermic peak at 153.3°C (ΔH = 44.29 J/g) corre-
spondent to its melting point. The thermogram
of Tet-loaded scaffolds exhibits no significant
difference in Tpeak and ΔH from that of modified
PLLA scaffolds, which could be explained by
the existent of Tet did not change the thermo-
dynamics of the scaffolds.
3.5 SEM
The morphologies of the scaffolds were
shown in Figure 5. What can be found was that
the scaffolds all acquire network structures
constructing of ultrafine fiber. Moreover, the
average fiber diameter and pore size of Tet-
loaded PLLA scaffolds varies little with that of
modified PLLA scaffolds. In other words, the
molecular structure of scaffolds keeps identical
after Tet containing. Therefore, the loading of
Tet did not change the morphous of the scaf-
folds. This would be helpful for Tet-loaded scaf-
folds to be used in chondrocyte tissue engineer-
ing field.
3.6 Drug release behaviors
The drug loading content was calculated
from the ratio of amount of drug containing in
the PLLA scaffold and the weight of PLLA scaf-
fold, and up to 0.652 mg/g. It was worth noting
that the experimental amount of loading drug
is much smaller than the theoretical amount.
It may be due to considerable dissolving of Tet
during the process of replacing THF with 50%
(V/V) ethanol and then with distilled water.
Therefore, it is of utmost importance to assay
the drug loading content of Tet-loaded PLLA
scaffolds. In addition, the Tet content has sig-
nificant influence on the behaviors of chondro-
cyte. It had been proved that low tetrandrine
was beneficial for chondrocyte proliferation,
chondrocyte activity and chondrocyte expres-
sion, and thus for chondrocyte tissue recon-
struction [26]. In this paper, the average drug
Fig. 3. X-ray diffractograms of Tet (a), PLLA
scaffolds (b) and Tet-loaded PLLA scaffolds (c).
Fig. 4. DSC thermograms of modified PLLA scaf-
folds (a) and Tet-loaded PLLA scaffolds (b).
Fig. 5. SEM photographs of modified PLLA scaffolds (left) and Tet-loaded PLLA scaffolds (right).
Table 2. Differential scanning calorimetric
data of PLLA scaffolds
Samples Tonset, °C Tpeak, °C ΔH (J·g–1)
modified PLLA
scaffolds 140.0 153.3 44.29
Tet-loaded
PLLA scaffolds 139.0 152.7 49.4
Functional materials, 24, 34 2017 665
Zhang Ye / Poly(lactic acid) scaffolds modified by ...
loading content of Tet-loaded PLLA scaffolds
was about 0.652 mg/g which favorable for Tet-
loaded scaffolds using in chondrocyte tissue en-
gineering field.
The release behaviors of Tet-loaded PLLA
scaffolds were reported in Figure 6. As can
be discovered, the initial burst effect was not
observed in all examined samples, which con-
firmed that Tet-loaded PLLA scaffolds could be
prepared without any residual drug on their
surfaces. In the initial stage, the release rate
increased slowly. After that, the drug released
from the scaffolds increased apparently. Tet
loaded into the pores of PLLA scaffolds showed
significant sustained release characteristics of
about 79.15% in 188 days. The scaffolds keep
good integrity through release studies.
Drug release behaviors also have important
effect on the behaviors of chondrocyte. It is gen-
erally assumed that a drug is released by sever-
al mechanics: (a) Fickian diffusion through the
polymer matrix, (b) diffusion through pores in
the matrix, and (c) drug liberation by polymer
erosion. For Tet-loaded PLLA scaffolds, Tet
is physically entrapped in PLLA matrix. And
the degradation of PLLA scaffolds during the
experiment period is ignorable which reported
in many studies [8, 19, 27, 28,]. Therefore, it
is speculated that the drug release from the
scaffolds is carried out mainly through Fickian
diffusion. Although the network of PLLA scaf-
folds which is the main diffusion barrier of Tet
can swell in water solution and that should be
a positive factor to improve Tet diffusion, Tet is
a lipophilic alkaloid and its solubility in water
is very low. This will result in the decrease of
Tet release rate.
4. Conclusions
This study explored the potential of Tet-
loaded PLLA scaffolds in cartilage tissue engi-
neering. XPS and FT-IR spectroscopy demon-
strated that Tet was contained in the scaffolds.
DSC, SEM and XRD confirmed that Tet did not
change the morphous, crystallinity and ther-
modynamics of the scaffolds. Release studies
revealed that Tet was released gradually, ap-
proximately 79.15% in 188 days. In addition,
the scaffolds keep good integrity through re-
lease studies. Therefore, Tet-loaded PLLA scaf-
folds offer a considerable potential in chondro-
cyte tissue engineering, thus broadening the
clinical application.
Acknowledgements
This research was performed by support
from the National Natural Science Foundation
of China (No. 30570495).
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