Photonic crystals in biology

Poster Session, Tuesday, June 15
Theme A1 - B702
Electros pun Hybrid Scaffolds for Bone Tissue Repair
1 *
1 urkey.
Abstract-The aim of this study is to develop novel hybrid (blend&layer by layer) tissue scaffolds for bone tissue repair by using electrospinning
method. PCL (poly--caprolactone), chitosan and hydroxyapatite (HA) nanoparticles were used as components for hybrid structures. 15 wt % of
PCL and 8 wt % of chitosan concentrations and 90/10 vol % PCL/chitosan weight ratio were selected in order to obtain uniform and bead free
fabrics. Detailed characterization studies performed in this study showed the desired properties of scaffolds for bioapplications. The control of
suitability of the developed hybrid scaffolds for cell culture applications by using osteoblast cells is under process.
Nanofibrous materials have been extensively studied as
scaffolding materials in tissue engineering and regenerative
medicine, due to the fact that the extracellular matrices (ECM)
of native tissues are nanofeatured structures, and cells attach
and proliferate better on nanofeatured structures than bulk
materials [1,2]. Recently, researchers have investigated
electrospinning of blend polymers as candidate materials for
biomedical applications because polymer blends have
provided an efficient way to fulfill new requirements for
material properties. Blends made of synthetic and natural
polymers can present the wide range of physicochemical
properties and processing techniques of synthetic polymers as
well as the biocompatibility and biological interactions of
natural polymers [3,4]. In addition, many researchers have
reported that incorporation of calcium carbonate (CaCO 3 ) or a
type of calcium phosphate such as hydroxyapatite (HA)
helped to improve osteoblast proliferation and differentiation
[5,6].
In the present contribution, novel PCL (poly--caprolactone)
and chitosan blend and layer by layer structures of hybrid
scaffolds filled with hydroxyapapite (HA) nanoparticles were
developed by using electrospinning method. PCL, due to its
slow degradation rate, is a good candidate to be used in bonescaffolding
applications. Chitosan is favorite for
bioapplications because of its biocompatible property and low
cost. HA nanoparticles (50-200 nm) prepared and
characterized in our previous study [7] were used.
In the first stage of the work, various solution/process
parameters such as concentration, PCL/chitosan weight ratios,
applied electric voltage, tip-collector distance were studied for
optimization of scaffolds. After optimization studies, the
concentrations for pure and hybrid (blend and layer by layer;
PCL/Chitosan/PCL&Chitosan/PCL/Chitosan) PCL and
chitosan scaffolds were chosen as 15 wt % of PCL and 8 wt %
of chitosan in order to obtain desired nanofabric structures
(uniform, bead free). The weight ratios of PCL and chitosan
were determined as 90/10 vol % for blend PCL/chitosan
scaffolds. PCL/Chitosan/PCL layer by layer structure was
selected for further studies. Applied electric voltages, tipcollector
distances were determined for each scaffolds. For the
HA modification of the scaffolds different concentrations (1.5,
5, 10, 20 wt%) of HA nanoparticles were added to
PCL/chitosan solutions before electrospinning process. In
addition to naked eye observation SEM analysis was also used
for the optimization of structures.
In the characterization stage, the prepared scaffolds were
first morphologically examined by SEM analysis. By using
computer software program (ImageJ, USA), average fiber
diameters, HA and inter fibers porosity sizes of scaffolds were
calculated from obtained SEM photographs.
Wettabilities of electrospun scaffolds were measured using
sessile drop water contact angle measurement by a optical
contact angle measurement (KSV, Finland) systems. The
contact angle measurement study showed that hydrophobic
characteristic of PCL scaffolds was decreased by adding
chitosan and HA components. The samples were cut in
rectangular strips with dimensions 40 mm × 5 mm, and tensile
properties were characterized by tensile testing machine
(Llyod Instruments LK-5K, UK) equipped with a 500 N load
cell. Elastic modulus, tensile strength and strain at break (%)
values of samples were determined as a result of mechanical
tests. FTIR-ATR analysis in the range of 500-4000 cm -1
wavelength was used for the chemical structure confirmation
of the prepared scaffolds. The obtained spectra showed that
the hybrid scaffolds represent the characteristic peaks of PCL,
chitosan and HA components. Swelling properties of
PCL/chitosan scaffolds were examined by PBS absorption
tests. In order to investigate the effect of chitosan on
biodegradation of prepared scaffolds, biodegradation studies
were carried out for the 7 th , 14 th , 21 st
and 28 th
days of
incubation in DMEM/F12 with chicken egg white lysozyme
medium. Additionally, controlled release of BSA (Bovine
Serum Albumin) studies was performed to have an idea about
the effect of HA nanoparticles with different weight ratios on
bone tissue repair.
In summary, the characterization studies carried out in this
work showed the desired properties of scaffolds for
bioapplications. In the future part of this work, the control of
suitability of prepared and well/detailed characterized hybrid
PCL/chitosan scaffolds for cell culture applications will be
performed by using osteoblast cells. This work was fully
supported by TUBA/LOREAL under “Young Women in
Science” program. Dr.
“Young Woman in Science” in Materials Science at 2009 with
this project.
*Corresponding author: 1Thtsasmazel@atilim.edu.tr
[1]J.A. Matthews, G.E. Wnek, D.G. Simpson, et al.
Biomacromolecules 3, 232 (2002).
[2] M. Pattison, S. Wurster, T. Webster, K. Haberstroh, Biomaterials
26, 249 (2005).
[3] Y. You, S.W. Lee, et al. Polymer Degradation and Stability 90,
441 (2005).
[4] S. Aparna, S.V. Madihally, Biomaterials 26, 5500 (2005).
[5] A. G. A. Coombes, S. C. Rizzi, M.Williamson, J. E. Barralet,
S. Downes, W. A. Wallace, Biomaterials 25, 315 (2004).
[6] K. Fujihara, M. Kotaki, S. Ramakrishna, Biomaterials 26, 4139
(2005).
[7] A.P. Sommer, M. Çehreli, et al. Crystal Growth&Design 5, 21
(2005).
6th Nanoscience and Nanotechnology Conference, zmir, 2010 211