bluuebunny/crossref_metadata_2025 huggingface dataset:
A Polycrystalline Analysis of Hexagonal Metal Based on the Homogenized Method
Authors: Tadano Yuichi , Kuroda Mitsutoshi , Noguchi Hirohisa , Shizawa Kazuyuki
Published: March 2009

In this study, a three-dimensional finite element formulation for polycrystalline plasticity
model based on the homogenization method has been presented. The homogenization method is one
of the useful procedures, which can evaluate the homogenized macroscopic material properties with
a periodical microstructure, so-called a unit cell. The present study focuses on hexagonal metals
such as titanium or magnesium. An assessment of flow stress by the presented method is conducted
and it is clarified how the method can reproduce the behavior of hexagonal metal.
Formability of Friction Stir Welded and Arc Welded 5083 Aluminum Alloy Sheets
Authors: Hirata Tomotake , Oguri T. , Hagino H. , Tanaka Tsutomu , Wook Chung Sung , Tsujikawa Masato , Takigawa Yorinobu , Higashi Kenji
Published: March 2009

The formability in friction stir and arc welded 5083 Al alloys was investigated. The elongation in friction stir welded material under uniaxial tensile test increased with the decrease in friction heat flow during friction stir welding (FSW) and the value of dome height under biaxial bulge test increased with friction heat flow. The ductility improved according to changes in FSW condition and FS-welded alloy sheet exhibited excellent formability.
Plastic Behavior of Polycrystalline Aluminum during Biaxial Compression with Strain Path Change
Authors: Shimizu Ichiro , Tada Naoya
Published: March 2009

Biaxial compression tests with an abrupt strain path change have been performed on
polycrystalline aluminum to investigate the plastic deformation behavior under complex strain
histories. Attentions are paid especially to the rapid change in the normal stresses due to the abrupt
strain path change. The influences of the prestrain amplitude and the angular relation of sequential
strain paths on the stress changes were also studied. The results showed that the transient increase of
the normal stresses related to the latent hardening phenomenon with strain path change as well as the
plastic anisotropy increase with the pre-straining amplitude. The transient increase in the stress was
also affected by the strain histories in the sequential compression tests with the strain path change.
The transient stress increment became large to the maximum then decreases with the angle between
the sequential paths.
Human Adipose Tissue-Derived Stem Cell Seeded Hyaluronic Acid-Collagen Scaffolds for Adipogenesis Investigated In Vivo
Authors: Moon Y.M. , Kim S.O. , Kim S. , Jeong Jae Ho
Published: March 2009

The purpose of this study is to confirm the possibility of regenerating actual fat tissue
using human adipose tissue-derived stem cells (ASCs) and hyaluronic acid-collagen sponge in
animal model. Human ASCs of young female adults were isolated and culture expanded in basal
media. At the second passage, cultured ASCs suspension containing 106 cells was applied on prewetted
scaffolds the hyaluronic acid-collagen sponge and the sponges was exposed to adipogenic
media for the 1week. Then the tissue engineered constructs were implanted into the subcutaneous
pocket on the back of immunodeficient athymic nude mice for 3 weeks. Hyaluronic acid-collagen
sponges without human ASCs were used as the control. After 3 weeks, specimens were harvested
and adipogenic potentials were assessed with histological examination, RT-PCR for PPAR-γ2
expression and G-3-PDH activity.
Tissue engineered fat tissue from ASCs and hyaluronic acid-collagen sponges demonstrated
PPAR-γ2 positive expression and positive Oil red O staining. The histologic study showed
definitive adipose tissue and rich vascular tissue within the engineered fat. Two-fold higher
activities of G-3-PDH were identified in experimental group after 3 weeks as compared to control.
By contrast, the specimen from control group did not show active vessel ingrowth and contained
only few cellular elements within the scaffold. The control specimens failed to demonstrate
adipogenic gene markers and were negative in oil red O staining.
In conclusion, human ASCs can be differentiated into adipocytes and actual fat tissue engineering
was possible with combination of adequate scaffold materials, such as hyaluronic acid-collagen
sponges. These data demonstrate that fat tissue engineered from human ASCs can retain predefined
shape and dimension for soft tissue augmentation and reconstruction of defects.
Bone Response to Cyclic Loading with Anodized Implants
Authors: Lee Byung Uk , Heo Seong Joo , Koak Jai Young , Kim Seong Kyun , Kim Yong Sik , Lim Young Jun , Kim Sung Hun , Han Chong Hyun
Published: March 2009

The purpose of this study was to evaluate the bone interface response to different surface
using bone remodeling rate (BRR) under cyclic loading. The tibiae of 10 New Zealand white rabbits
were used. Each tibia of rabbits received 2 implants, one with anodic oxidation surface and the
other with machined surface. Dynamic loading, a cyclic load of 100 N with 100 cycles was applied
for 2 weeks. All implants were divided into 4 groups according to surface treatment and loading; (1)
machined surface, unloaded, (2) anodic oxidation surface, unloaded, (3) machined surface, loaded,
and (4) anodic oxidation surface, loaded. To determine the rate of bone formation, a series of
fluorochrome bone labeling materials (tetracycline, alizarin red, and calcein green) were
administrated intramuscularly at 10, 11, 12 weeks. To study the formation time of new bone,
ground sections were examined under confocal laser scanning microscopy. Resonance frequency
analysis (RFA) values were measured at the time of first surgery, second surgery and
sacrifice. From this study, it was concluded that implants with anodic oxidation surface had higher
value than machined surface on RFA measurement and anodic oxidation surface has more
resistance to loading than machined surface.
Evaluation of Efficacy and Safety of Stem Cells as a Therapeutics, Especially Focusing on Bone Marrow Derived Stromal Cells
Authors: Jung Ho Sun , Park Min Sung , Han Seung Hwan , Lee Jin Woo
Published: March 2009

Bone marrow derived-stromal cells (BMSCs) are pluriplotent progenitors for a
variety of cell types, including osteoblast, chondrocyte, adipocyte, and so on. Stem cell research
has enormous potential in the future clinical treatment of a wide range of diseases. Tracking stem
cell localization, survival, differentiation, and proliferation after transplantation in living subjects
is essential for understanding stem cell biology and physiology. However, we don’t have exact
evaluation methods and safeguards for clinical application. In this study, we investigated
tracking BMSCs differentiation, localization, toxicity, and migration in vivo. The fluorescent
vector used in our studies did not affect BMSCs viability or their ability to undergo osteogenic
and adipogenic differentiation in vitro. During differentiation, EGFP-BMSCs by Oil Red O and
Alizarin Red S were stained. EGFP-BMSCs were transplanted into the femoral region in
autologous rabbit. After one month, these cells were detectable by confocal microscopy and RTPCR.
Transplanted EGFP-BMSCs were not detected another organs (spleen, kidney, liver, and
muscle) in immunohistochemistry and RT-PCR. In organ-function test and cell-toxicity
examination, there is no difference between the before and after EGFP-BMSCs transplantation.
we observed that transplanted EGFP-BMSCs were not affected cell-toxicity and migration. This
results offer some evaluation methods and safeguards for clinical application using BMSCs. In
further study, it will be needed to test reproductive and developmental toxicity after
transplantation and observe migration of EGFP-BMSCs after transplantation.
Development of Chitosan Dermal Scaffold and its Characterization
Authors: Kim Chun Ho , Choi Young Ju , Lee Seung Jae , Gin Yong Jae , Son Young Sook
Published: March 2009

We have developed tensile and porous neutralized chitosan scaffold (NCS) whose pore
size was controlled by freezing temperatures. At -70 oC, mean pore size of 112 μm was obtained. At
-196 oC, mean pore size was approximately 70 μm at surface. The scaffold processed at -196 oC
showed homogeneous small pores with structural integrity, which may be more useful as a guidance
dermal scaffold for inward cell migration. The scaffold processed at –70 oC may be more useful for
cell loading scaffold requiring wider pore. Since biodegradability and biocompatibility are crucial
parameters for the development of dermal scaffold, we evaluated the rate of NCS degradation in the
culture medium containing lysozyme by measuring weight loss as well as mean molecular weight of
the scaffold. Approximately 40% weight loss at one week and 70% weight loss at 30 days was
observed, which means that 70% of the scaffold will be degraded and releasable if the wound
microenvironment is similar to the test condition. Again, mean molecular weight of the scaffold
based on gel permeation chromatography was less than 1x105 after 10 day incubation. This result
suggests that degradation of the NCS begins earlier than the observation of gross weight loss. We
also evaluated whether degradation product of NCS are toxic to the human dermal fibroblast or not.
Chitosan oligomer up to 1.0 mg/ml, which corresponds to 10% of the total degradation derivatives
of the NCS, did not affect the viability of the dermal fibroblast based on MTT assay. This result
along with the biodegradation data suggests that the NCS can be developed as suitable dermal
scaffold.
Increase in the Biocompatibility of the Neutralized Chitosan Dermal Scaffold by Reconstruction of Wound Healing Microenvironment: In Vitro Study
Authors: Youn Yong Ha , Kim Chun Ho , Choi Young Ju , Gin Yong Jae , Son Young Sook
Published: March 2009

The porous neutralized chitosan scaffold (NCS) was prepared by freeze-dry method. Its
poor cell binding capacity was improved approximately five folds by mixing or coating of
atelomeric type I collagen. In order to recreate wound-healing microenvironment within the NCS
for the better wound healing effect, various concentrations of bFGF and fibronectin (FN) were
supplied in the secondary freeze-dry process of the scaffold. NCS+ bFGF and NCS+FN improved
the cell binding capacity by four folds and three folds respectively. Therefore supplementation of
collagen, b-FGF and/or fibronectin in the NCS can improve the biocompatibility of the chitosanbased
scaffold which itself revealed poor cell binding capacity.
The Role of Endothelial Cells Differentiated from Bone Marrow Stem Cells in Cartilage and Bone Regeneration
Authors: Chung Ho Yun , Oh Eun Jung , Choi Jin Hyun , Cho Byung Chae
Published: March 2009

Mesenchymal stem cells (MSCs) from bone marrow seem to be the one of best
candidates to regenerate injured tissue. However, recent advances in application of MSCs toward
large tissue regeneration are faced with lack of vascularity. In this study, endothelial cells
differentiated from MSCs were applied for constructing tissue-engineered bone and cartilage. It was
found that endothelial cells from MSCs play an important role of providing vasculature.
Effect of Collagen Coating on Lipid Accumulation and Differentiation on 3T3-L1 Preadipocyte Treated with Conjugated Linoleic Acid
Authors: Moon Hyun Seuk , Lee Hong Gu , Song Ho Hyun , Choi Yun Jaie , Cho Chong Su
Published: March 2009

The purpose of this study is to make use of trans10,cis12 CLA (t-CLA) that has potential
for proliferation and differentiation to form adipocyte on the collagen-coated surface. Results
provided evidences of good adhesion, growth, viability, and differentiation of adipocyte on
collagen-coated surface compared with non-coated surface. Also, the results showed that mouse
3T3-L1 preadipocyte can be successfully and reproducibly cultured on the collagen-coated surface,
and the adipocyte precursor cells placed on the collagen-coated surface are able to undergo full
maturation into adipocytes in the control cells. Moreover, glycerol-3-phosphate dehydrogenase
(GPDH) activity in 3T3-L1 preadipocyte cultured on collagen-coated surface with t-CLA was
higher than that on polystyrene (PS) surface due to higher cell adhesion and cell viability. These
results suggest that collagen coating may provide a promising approach to develop a new adipocyte
replacement strategy using CLA.
Bone Regeneration Materials
Authors: Kikuchi Masanori , Tanaka M.
Published: March 2009

Biomaterials Center is composed of five groups and collaborate each other to examine
interdisciplinary fields of biomaterials. In the ceramics-based biomaterials research, we have been
developing three novel bone regeneration materials, i.e., high-porosity hydroxyapatite (HAp)
ceramics with high-strength, guided bone regeneration (GBR) membranes and bone-like
nanocomposite composed of HAp and collagen. The GBR membrane composed of β-tricalcium
phosphate and biodegradable copolymer of lactide, glycolide and ε-caprolactone has thermoplastic,
pH auto-adjustment and enough mechanical property to protect an invasion of surrounding tissues.
With the membrane, bone defect up to 20 × 10 × 10 mm3 in length in mandibles and segmental
bone defect up to 20 mm in length in tibiae of beagles are regenerated without any additional bone
fillers or cell transplantations. The bone-like nanocomposite is synthesized by a co-precipitation of
HAp and collagen via their self-organization. The dense composite has a half to quarter mechanical
strength (40 MPa) to cortical bone and the porous one demonstrates sponge-like viscoelasticity.
The composites implanted into bone are incorporated into bone remodeling metabolism like as
autogenous bone graft, i.e., they are resorbed by osteolasts followed by osteogenesis by osteoblasts.
Investigation of Pore Size Effect on Cell Compatibility Using Pore Size Gradient Chitosan Scaffold
Authors: Lim Sung Mook , Oh Se Heang , Park Il Kyu , Lee Jin Ho
Published: March 2009

Chitosan cylindrical scaffolds with gradually increasing pore size along the longitudinal
direction were fabricated by a novel centrifugation method to investigate pore size effect on cell
interactions. The scaffold was fabricated by the centrifugation of a cylindrical mold containing fibril-like
chitosans. The pore size ranges of the scaffold could be controlled by adjusting the centrifugal speed: the
scaffold with gradually increasing pore size (from ~80 #m to ~400 #m) and porosity (from ~82 % to
~93 %) along the cylindrical axis was obtained by applying the centrifugal speed, 3,000 rpm. The scaffold
sections were examined for their in vitro cell interactions using different kinds of cells (fibroblasts,
chondrocytes, and osteoblasts) in terms of scaffold pore sizes. It was observed that different kinds of cells
were shown to have different pore size ranges in the scaffold for effective cell growth. The chitosan
scaffold section with ~400 #m pore size showed better cell growth for chondrocytes and osteoblasts,
while the scaffold section with ~190 #m pore size was better for fibroblast growth. The pore size gradient
scaffolds fabricated by the centrifugation method can be a good tool for the systematic studies of the
interactions between cells or tissues and scaffolds with different pore size.
Preparation and In Vitro Evaluation of Nerve Conduit Using Electro-Spun Biodegradable Polymers
Authors: Bae Hong Ki , Chung Chong Pyong , Chung Dong June
Published: March 2009

In this study, we find out the possibilities to make conduit for nerve regeneration using
biodegradable polymers, which have enough mechanical strength in surgery. Cell adhesion (PC12) behaviors
about various nerve conduits have not great difference compared to control. This is regarded due to specific
structure of nerve conduits formed nano-fibers. In the case of PPD, we observed better phenotype of adhered
cell than PLGA samples. Also, PPD-PLGA bi-layered nerve conduits were more effective than PLGA nerve
conduit for in vitro evaluation.
Enhancement of the Strength and Stability of Ultraviolet-Irradiated Acellular Dermal Matrix by Adding Glucose
Authors: Kim Jin Young , Ahn Jae Hyoung , Song Seok Beom , Seo Seog Jin , Chae Ji Hwa , Kim Tae Woon , Lee Kwang Won , Kang Nak Heon , Kim Jin , Cho Chong Su , Kang Ke Won
Published: March 2009

In theory, Ultraviolet (UV)-generated free radicals can expedite Acellular dermal matrix
(ADM) crosslinking with glucose via the formation of reactive, linear glucose molecules. The aim
of this study is to maintain strength and stability of UV-irradiated ADM without the introduction of
cytotoxic chemical crosslinkers. The strength and stability changes of ADM by UV-irradiated with
glucose (GLUC) were investigated under various conditions. ADM strength and stability were
determined by tensile testing, differential scanning calorimetry (DSC), and swelling ratio. After
exposure to UV-irradiation, ADM containing glucose revealed different mechanical properties
compare to ADM without glucose, greater resistance to enzymatic degradation, and higher heatdenatured
breaking loads. DSC explained that glucose-incorporated ADM sterilized by UVirradiation
decreased peak width (Tpeak-Ts) compared to one another. On the other hand, Area (J/g)
and Ts increased glucose-incorporated ADM. The exposure of ADM to UV caused significant
increase in hydration, but a significant decrease in the swelling ratio compared with the nonirradiated
ADM. These data strongly suggests that free radical-dependent, glucose-derived
crosslinks provide enhanced strength and enzyme resistance in glucose-incorporated, UV-exposed
ADM.
Effect of Poly (Lactic–Co–Glycolic Acid) (75:25)/ Hydroxyapatite Composite on Chondrocyte Culture for Tissue Reconstruction
Authors: Lee Jung Bok , Yu Seong Mi , Lee Sang Gil , Choi Jae Bong , Kim Jeong Koo
Published: March 2009

PLGA (75:25)/hydroxyapatite (HA) composite films were fabricated by solvent-casting method to
investigate the effect of various hydroxyapatite content ratio to the PLGA film for cellular
attachment and proliferation. Mechanical property of the composite film was characterized by
tensile test. The ultimate tensile strength of 10% HA content film was two folds higher than control
group. The surface of the film was characterized by contact angle measurement. The PLGA/HA
composite film was more hydrophilic than control film. In vitro chondrocyte responses to the
composite films were measured by cellular attachment and proliferation test. The attached and
proliferated cells were significantly higher on PLGA/HA (10%) composite film than control group
(1.44 times higher in attachment test and 1.31 times higher for 6th-day at culture in proliferation
assaying, p<0.05). Base on these finding, the PLGA/HA (10%) composite was effective for the cell
attachment for the initial stage of cultivation and cell proliferation.
The Effects of Chitosan-Tetracycline Membrane on Periodontal Regeneration of One-Wall Intrabony Defects in Beagle Dogs
Authors: Han Kwang Hee , Chae Gyung Joon , Choi Jung Yoo , Jung Ui Won , Lee Yong Keun , Choi Seong Ho
Published: March 2009

The aim of this study was to evaluate the regenerative effects of chitosan membranes
containing tetracycline (TC) applied to surgically created one-wall intrabony defects in beagle dogs.
The defects either received chitosan membrane (CH), chitosan membrane containing 0.5%, 1% TC
(CH-TC0.5, CH-TC1.0) or flap operation only. The animals were sacrificed 8 weeks after the
experimental surgery, and comparative histological and histometric examinations were done. The
amount of junctional epithelium migration and connective tissue adhesion did not show any
statistically significant differences among the groups. The amount of new cementum regeneration,
and new bone regeneration were significantly greater in CH-TC1.0 group than the control (P<0.05).
The results suggest that chitosan membrane combined with 1.0% TC may have beneficial effect on
the regeneration of bone and cementum in intrabony periodontal defects.
Hydroxyl Groups in Demineralized Bone Matrix
Authors: Seo Seog Jin , Song Seok Beom , Chae Ji Hwa , Kim Jin Young , Ahn Jae Hyoung , Kim Tae Woon , Hwang Ho Chan , Kim Jin , Lee Kwang Won , Kang Nak Heon , Cho Chong Su , Kang Ke Won
Published: March 2009

Human demineralized bone matrix (DBM) containing bone morphogenetic proteins
(BMPs) is naturally biocompatible and can be remodeled by patients’ own bone. The major
shortcoming of many of the currently used DBM gel formulations is that they have a tendency to
flow, particularly if there is continuous bleeding at the application site. In this study, the
physicochemical properties of human DBM were examined to improve the efficiency of DBM
formulations. DBM remarkably showed higher water absorption than nondemineralized bone
powder after 150 min. Hydroxyl groups in DBM appeared in fourier transform infrared analysis,
although hydroxyl band in nondemineralized bone powder was not observed. The results suggested
that hydrogels such as CMC, hyaluronic acid, or poloxamer as carriers can be applied for injectable
DBM products, such as gel or putty types.
Cartilage Tissue Engineering using a Elastic Poly (L-Lactide-co-ε-Caprolactone) Scaffold
Authors: Jung Young Mee , Kim Soo Hyun , Kim Sang Heon , Kim Young Ha , Min Byoung Goo
Published: March 2009

Mechano-active scaffolds were fabricated from very elastic
poly(L-lactide-co-ε-carprolactone). The scaffolds with 80 % porosity and 300~500 μm pore size
were prepared by a gel-pressing method. As a control group for elastic properties of polymer
scaffolds, rigid poly L-lactide scaffolds were fabricated. The scaffolds were seeded with
chondrocytes and cultured to evaluate the effect of elastic properties of polymer scaffolds for the
differentiation and the ECM secretion of chondrocytes. Also, the chondrocytes-seeded constructs
were implanted in nude mice subcutaneously to investigate their biocompatibility and cartilage
formation. From the biochemical analyses, chondrogenic differentiation was sustained and
enhanced significantly and chondral extracellular matrix was increased through mechanical
stimulation of dynamic environment in the dynamic body systems. Histological analysis showed
that implants of PLCL constructs formed mature and well-developed cartilaginous tissue, as
evidenced by chondrocytes within lacunae. Consequently, the elastic PLCL scaffolds could be used
to engineer cartilage in mechanically dynamic environments
Mechano-Active Cartilage Tissue Engineering: The Effect of Dynamic Compressive Stimulation
Authors: Jung Young Mee , Kim Soo Hyun , Kim Sang Heon , Kim Young Ha , Xie Jun , Matsuda Takehisa , Min Byoung Goo
Published: March 2009

Mechano-active scaffolds were fabricated from very elastic
poly(lactide-co-carprolactone) by a gel-pressing method. The scaffolds were seeded with bone
marrow stromal cells and the continuous compressive deformation was applied to cell-polymer
constructs in the chondrogenic media. Then, they were implanted in nude mice subcutaneously to
evaluate for the effect of dynamic compression for regeneration of cartilage. From the biochemical
analyses, chondrogenic differentiation was sustained and enhanced significantly and chondral
extracellular matrix was increased through mechanical stimulation. Histological analyses showed
that implants stimulated mechanically formed mature and well-developed cartilaginous tissue, as
evidenced by bone marrow derived chondrocytes within lacunae. Consequently, the periodic
application of dynamic compression can encourage bone marrow stromal cells to differentiation to
chondrogenic lineage and to maintain their phenotypes.
Glucosylated Polypropylenimine Dendrimer as a Novel Gene Carrier
Authors: Kim You Kyoung , Park In Kyu , Jiang Hu Lin , Arote Rohidas B. , Jeong Hwan Jeong , Kim Eun Mi , Cho Myung Haing , Bom Hee Seung , Cho Chong Su
Published: March 2009

Polypropylenimine (PPI) dendrimers have been used by many researchers as gene
delivery carriers due to their high functionality. Glucose as a kind of carbohydrate is biocompatible
and hydrophilic. In this study, we synthesized glucosylated PPI (G-PPI) dendrimers to reduce
cytotoxicity. Glucose substitution of G-PPI dendrimers was determined by the sulfuric acid micromethod.
The G-PPI dendrimer was complexed with plasmid DNA in various N/P ratios, and the
complex was characterized. G-PPI dendrimers showed good DNA binding ability and high
protection of DNA from nuclease attack. The G-PPI dendrimer had low cytotoxicity compared to
PPI dendrimer by cytotoxicity assay. Also, transfection efficiency was influenced by glucosylation
degree and the transfection efficiency for the G-PPI-5 was slightly higher than that of PPI
dendrimer in HeLa cell line.
Enhance of Tumor Targeting by Receptor-Mediated Endocytosis Using Low Molecular Water-Soluble Chitosan Nanoparticles Loaded with Anticancer Agent
Authors: Kim Dong Gon , Jang Min Ja , Choi Chang Yong , Kim Tae Hyeong , Jang Mi Kyeong , Nah Jae Woon
Published: March 2009

In this study, we prepared using low molecular weight water-soluble chitosan nanoparticle loaded
paclitaxel (LMWSC-NPT) and investigated the potential as a drug carrier which is able to accumulate in the
tumor site. In the experiment of receptor-mediated endocytosis, LMWSC-NPT was treated with sodium azid
(NaN3) as an inhibitor of endocytosis process. As results, the antitumor activity of LMWSC-NPT treated
with sodium azid didn’t show but LMWSC-NPT was shown the high antitumor activity. Therefore,
LMWSC-NPs modified with hydrophobic group will be useful anticancer agent carrier via receptor-mediated
endocytosis.
Fabrication of Bio-Composite Drug Delivery System Using Rapid Prototyping Technology
Authors: Chu Won Shik , Kim Sung Geun , Kim Hyung Jung , Lee Caroline S. , Ahn Sung Hoon
Published: March 2009

The rapid prototyping (RP) technology has advanced in various fields such as verification
of design, and functional test. Recently, researchers have studied bio-materials to fabricate
functional bio-RP parts. In this research, a nano composite deposition system (NCDS) was
developed to fabricate three-dimensional functional parts for bio-applications. In the hybrid process,
the material removal process by mechanical micro machining and/or the deposition process are
combined. NCDS uses biocompatible or biodegradable polymer resin as matrix and various bioceramics
to form bio-composite materials. To test drug release rate in vivo environment, two
different types of drug delivery system (DDS) were fabricated using the bio-composite materials. 1)
Container type DDS used poly(DL-lactide-co-glycolide acid)(50:50) and 5-fluorouracil as the drug
composite while polycaprolactone(PCL) served as the container of the drug. 2) Scaffold type DDS
formed porous microstructure with poly(DL-lactide-co-glycolide acid)(50:50) and 5-fluorouracil
composite. The effect of geometry of the DDS on release rate of drug is under investigation.
Release Profile of a Model Protein Drug Depending on the Stability of Microspheres Based on Polyelectrolyte Complex
Authors: Kim Sung Won , Nam Yun Sik , Min Yeon Jin , Kim Jong Ho , Kim Kwang Meyong , Choi Kui Won , Noh In Sup , Kwon Ik Chan
Published: March 2009

Stability and disintegration of natural polyelectrolyte complex microspheres for protein
drugs delivery have been extensively investigated because of their great influence on the drug
release patterns. In this study, we tested stability of microspheres with alginate (Alg) core layered
by either chitosan (Chi) or glycol chitosan (GChi) by examining release profiles of fluorophorelabeled
bovine serum albumin (BSA) and lysozyme (Lys) from the microspheres. While GChi shell
was disintegrated quickly, Chi-shell microspheres showed good stability in PBS. Disintegration of
the coated layer induced the core material instable. The results indicated that while the charges of
the shell material provided additional diffusion barrier against the protein release, the key factor to
hold the proteins inside the microspheres was the integrity of the outer coating layer.
All-Trans Retinoic Acid (atRA) Release from atRA-Loaded Folate-Poly(Ethylene Glycol)/Polyethylenimine Nanoparticles for Folate-Mediated Tumor Targeting
Authors: Yoo Mi Kyong , Kim You Kyoung , Jeong Hwan Jeong , Bom Hee Seung , Cho Chong Su
Published: March 2009

To improve the specific accumulation in tumor sites and aqueous solubility of atRA, the
core-shell type of folate-PEG-g-PEI/atRA nanoparticles were prepared by complexation between
cationic PEI segments in the copolymers and anionic charged atRA, and then characterized by 1HNMR,
ELS, XRD, and TEM. In vitro atRA release from the nanoparticles was investigated as a
function of drug content in sink condition. Cytotocicity of atRA against HepG2, KB cell lines were
also evaluated by MTT assay. The lower the drug content, the faster atRA release. atRA
incorporated in folate-PEG-g-PEI/atRA nanoparticles showed much higher cytotoxic effect
compared with atRA itself.
Synthesis and Characterization of Polyethylenimine-Graft-Poly(L-Lactide-Co-Glycolide) Block Copolymers for Gene Delivery
Authors: Jeon Oju , Song Su Jin , Lee Min Hyung , Seo Sang Woo , Choi Cha Yong , Kim Byoung Soo
Published: March 2009

Polyethylenimine-graft-poly(L-lactide-co-glycolide) (PEI-g-PLGA) block copolymers
were prepared by a ring-opening polymerization of L-lactide and glycolide using PEI as a macroinitiator
and stannous octoate as a catalyst in dimethylformamide at 100 °C. The molecular structure
of the block copolymers was evaluated with 1H-NMR, and the molecular weight of the block
copolymers was determined with gel permeation chromatography. The thermal properties were
investigated using differential scanning calorimetery and thermogravimetric analysis. The zetapotential
of the pDNA/copolymer complexes was evaluated with dynamic laser light scattering.
Cytotoxicity and gene transfection efficiency of PEI-g-PLGA were tested in vitro using human
embryonic kidney 293 cell culture. The pDNA/copolymer complexes (N/P = 10) showed a lower
zeta-potential than pDNA/PEI25kDa complex, suggesting the lower toxicity of the
pDNA/copolymer complexes. The copolymer composition was found to significantly affect the
gene transfection efficiency of the pDNA/copolymer complexes. The copolymers with lower
contents of PLGA showed higher gene transfection efficiency. These results indicate that these
block copolymers are promising candidates for gene delivery vehicles, featuring good
biocompatibility, potential biodegradability, and relatively high gene transfection efficiency.
A Novel Degradation Controlled Hyaluronic Acid Derivatives
Authors: Oh Eun Ju , Kim Ji Seok , Hahn Sei Kwang
Published: March 2009

A novel protocol to control the molecular degradation of hyaluronic acid (HA) was
successfully developed. HA has a different conformational structure in water and in organic solvent,
and the carboxyl group of HA is known to be the recognition site of CD44 and hyaluronidase.
Based on these facts, HA was chemically modified in the mixed solvent of water and ethanol by
grafting adipic acid dihydrazide (ADH) to the carboxyl group of HA, which resulted in high degree
of ADH modification up to 85 mol% with controlled degradation of HA by hyaluronidase. The
degradation controlled HA-ADH will be assessed for various tissue engineering applications.
The Study of Antibiotic Drug-Loaded Polymer Films for the Prevention of the Infection of External Fixation Devices
Authors: Lee Moon Kyu , Lee Chang Yang , Kim Dong Ryul , Kwon Ik Chan , Choi Kui Won
Published: March 2009

The purpose of the present study was to develop a polymer film loaded with drug to
effectively prevent pin tract infection. It was found that the polymer, poly ethylene-co-vinyl acetate
blended with tetrahydrofuran, showed better flexibility and deformability than the other polymers:
poly caprolactone18 and poly caprolactone44. Polymer films, poly ethylene-co-vinyl acetate, were
divided into five testing groups dependent on the loading concentration of rifampici (5, 10, 15, and
20 wt %). The surface morphology of polymer films was examined by a scanning electron
microscopy. It was found that the concentration of drug was a main factor to determine the
roughness of the film. Considering the roughness of polymer films, 5 wt % of rifampicin might be
the maximum concentration for further applications. Hence, the antibiotic drug-loaded polymer
films were manufactured by mixing poly(ethylene-co-vinylacetate) and tetrahydrofuran with
rifampicin(antibiotic drug). The film cast was designed as a shape of disk (inner Ø5mm and outer
Ø20mm) to be suitable for pins for external fixation in orhtopaedics. The drug-loaded polymer
solvent, the amount of 0.6cc, was molded into the disk-shaped film and dried into a airtight box at
15°C for 24 hrs. The drug release characteristics(1, 2, 3, 4 and 5 wt%) were examined as a function
of soaking time in phosphate buffered saline (PBS, 10 ml) using an enzyme-linked immunosorbent
assay. Rifampicin was linearly released for first 100 hrs(~4 days) for all antibiotic drug-loaded
polymer films. Afterward, the drug was released at a slower pace as a function of square root of
time until 1000 hrs (~40 days). This slow drug release can be explained by their hydrophobic
characteristics of poly ethylene-co-vinyl acetate and rifampicin. The antibiotic drug-loaded polymer
film can be intrinsically able to prevent the bacteria adhesion by wrapping the pin track area, and
perform active and effective infection-resistant by a sustained antibiotic-release.
Current Density Contour Map of TiNi Shape Memory Alloy in Sulfate Solutions
Authors: Na Seung Chan , Park Seung Ho , Hwang Woon Suk
Published: March 2009

In this study, a current density contour map of TiNi shape memory alloy in sodium
sulfate solutions was constructed by potentiodynamic polarization technique. The current density
contour map of TiNi alloy, constructed in a 0.5 M sodium sulfate solution over the pH range 1 to 13
at 37oC, showed only hydrogen evolution region, passive region, and oxygen evolution region. The
localized corrosion region did not exist and the susceptibility of localized corrosion was not
exhibited. We also investigated the effects of chloride ions on the pitting corrosion of TiNi alloy in
sodium sulfate solutions. Pitting corrosion occurred with addition of 0.2 M NaCl in a sulfate
solution. And it was observed that pitting potential got lower as the concentration of chloride ion
went up. However, repassivation potential was not affected by the addition of chloride ion up to 0.5
M. It is concluded that a TiNi shape memory alloy exists as a passive state and a good corrosion
resistance in sulfate solutions over the pH range 1 to 13, and the sulfate ion performs a role of
inhibiting localized corrosion in chloride environment.
The Characterization of the Nano–Micro Hybrid Structure of Titanium Surface and Osteoblast Response to the Surface
Authors: Hwang Jae Sun , Oh Keun Taek , Kim Kyoung Nam , Kim Kwang Mahn
Published: March 2009

The titanium oxide layer with nano–micro hybrid structure on the titanium substrate was
formed by grit-blasting and anodic oxidation treatment. A micro rough surface can be formed by
grit-blasting and nanotube arrays can be formed by anodic oxidation or NaOH treatment after anodic
oxidation. We investigated the surface characterization on titanium and the response of the osteoblast
like cell (MG-63) to the surfaces made by different treatments. Surface structure (morphology),
wettability characterized by SEM, contact angle. The attachment and proliferation behavior of MG-63
cells on the titanium surface by different surface treatments were characterized by SEM observation
and MTT assay.The attachment and proliferation of osteoblast cells is accelerated by the topography
of the nano structure like a nanotube, the nano surface acts as an attachment point for the filopodia of
growing cells. Nano structure increases surface area and nano-micro structure significantly increases
surface area. Such nano–micro hybrid structure on the titanium substrate can be useful for a
well-adhered bioactive surface layer on Ti implant used metals for orthopedic and dental implants.
A Histomophometric Analysis of Bone Healing around Zirconia Implant
Authors: Lee Jeong Taek , Heo Seong Joo , Koak Jai Young , Kim Seong Kyun , Lee Su Young , Kim Hyoun Ee , Han Chong Hyun
Published: March 2009

Zirconia was introduced into the dentistry as a metal-replacement material because of its
outstanding mechanical properties like high flexural strength and fracture toughness. The purpose
of this study was to evaluate bone response and examine the surface characteristics of zirconiabased
implant. Screw shaped c.p. titanium implants(group 1), HA-based composite implants(group
2), HA/FA coated ZrO2 implants(group 3) and FA coated ZrO2 implants(group 4) were installed in
rabbit tibias. After 4 and 12 weeks of healing period, the histomorphometric analysis was performed
with an Olympus BX microscope connected to a computer. The percentage of bone-to-implant
contact in the 3 best consecutive threads and the percentage of bone inside the same threads were
calculated. the present study demonstrated the excellent bone response of ZrO2-based implants
fabricated by various methods to combine the advantages of ZrO2, HA, and FA.
Synthesis of Iron Oxide Nanowires by Heating Iron Foils
Authors: Kim Hyoun Woo , Shim S.H. , O B.H. , Lee S.G. , Park S.G. , Lee El Hang
Published: March 2009

We have fabricated the iron oxide nanowires directly from iron foils through the simple
heating in N2 ambient. We have characterized the samples by means of scanning electron microscopy,
transmission electron microscopy, energy-dispersive X-ray (EDX) spectroscopy, and selected area
diffraction pattern. The EDX spectrum revealed that the nanowires contained elements of Fe and O.
The iron oxide nanowires were crystalline with diameters in the range of 30-200 nm. We have
discussed the possible growth mechanisms.
Titanium and Titanium Alloy Castings for Biomedical Application
Authors: Sung Si Young , Kim Myoung Gyun , Kim Young Jig
Published: March 2009

The aim of this study is to optimize the economic net-shape forming of titanium and
titanium alloys for the biomedical application. The alpha-case formation reaction between titanium,
and Al2O3, ZrO2, CaO stabilized ZrO2 and ZrSiO4 mold were examined in a plasma arc melting
furnace. Regardless of the thermodynamic approach, α-case formation reactions still remain to be
eliminated with the complex chemical milling processes. The reason why the α-case generated
cannot be explained by the conventional α-case formation mechanism. However, from the
experimental results and thermodynamic consideration, it can be confirmed that the α-case is
formed not only by interstitial oxygen atoms but also by substitutional metal atoms dissolved from
mold materials. Based on the interstitial and substitutional α-case formation mechanism, α-case
controlled net-shape forming of titanium and titanium alloys can be possible for the biomedical
application.
Mechanical Performance of PRIMA OCT System under Interconnection Testing and Corpectomy Testing
Authors: Kim Cheol Woong , Kang Bong Su
Published: March 2009

The fixation of the vertebral column using transpedicular screws is a well-establish
technique. Multi-axial pedicle screw designs allow deviation of the screw away from the
perpendicular to the longitudinal rod, which facilitates application of a screw-rod system such as
PRIMA OCT into the curved spine. This study was performed a static (compression bending and
torsion) and dynamic (compression bending fatigue) empirical analysis of PRIMA OCT component
such as pedicle screw, rod and set screw based on the guideline of ASTM F136-98 using Ultra-high
Molecular Weight Polyethylene (UHMWPE) blocks as test vertebral bodies.
Preparation of Nano-Ceramic Composite as Dental Prosthetic Material
Authors: Ma J. , Zhao K. , Shi B. , Zhang Xing Dong , Chao Yong Lie , Li Xu Dong
Published: March 2009

Zirconia toughened alumina (ZTA) nano-ceramic composite has excellent mechanical properties. Preparation of ZTA was conducted in the present study with an attempt to use as dental ceramics. On the basis of the study on the effect of the die pressing forces on the density and Vickers hardness of the sintered ZTA, additive aids TiO2, MgO, SiO2 and CaO were introduced in order to reduce the sintering temperature of ZTA nano-ceramic composite with good densification. Scanning electron microscopy was employed to evaluate the microstructural morphology. Phase composition was confirmed by using X-ray diffraction. Thermal analysis was further used to study the structural change. The results indicated that the ZTA product sintered at 1450°C had dense and uniform microstructure due to the combinative effect of additive aids, including the formation of an intermediate compound. This study suggested that such ZTA nano-ceramics had potential applications as dental prosthetic materials.
Mechanical Properties on Gradient Bioceramic Composite Coating Produced by Wide-Band Laser Cladding
Authors: Liu Qi Bin , Yang Bang Cheng
Published: March 2009

To eliminate thermal stress during laser cladding and to raise the bonding strength between
substrate and coating, composition gradient coatings are designed and fabricated by using wideband
laser cladding technique on a Ti alloy. And mechanical properties on coating is studied. The
experimental results indicate that the bonding strength between coating and substrate is fairly high,
above 38.8MPa. The highest microhardness is obtained for coating containing 0.6wt.% Y2O3
1062HV0.1 and 1405HV0.1, respectively at bioceramic coating and alloyed transition layer. The
average tensile strength, bending strength, and elastic modules of coatings are 767.83MPa,
1671.65MPa, and 13.98GPa, respectively.
Microstructure and Biocompatibility of Gradient Bioceramic Composite Coating Fabricated by Wide-Band Laser Cladding
Authors: Liu Qi Bin , Li Wen Fei , Yang Bang Cheng
Published: March 2009

In this study, microstructure and biocompatibility of gradient bioceramic composite coating
fabricated by Wide-Band Laser Cladding is investigated. The experimental results indicate that the
coating consists of an alloyed transition layer and the bioceramic coating. The bioceramic coating is
mainly comprised of HA, CaTiO3, CaO, α-TCP, β-TCP and TiO. The coral-shaped structure and
short-rod piled structure existing on the surface of coating. After the implantation of the bioceramic
coatings into dogs’ femur for 6, 12, and 24 weeks, hypersusceptibility, rejection and pathological
changes are not found. No fiber cyst, necrosis of bone tissue and chronic inflammation obviously
appear through slice observation of hard tissues. The bioceramic coating with different ratios of Ca :
P have different abilities to induce osteogenesis. At Ca: P=1.4 and 0.6wt.% Y2O3 (No.3 sample), the
bioceramic coating is of best bioactivity and biocompatibility.
Ca-P Formation on Poly-L-Lactide/β-Tricalcium Phosphate Composite Scaffold in Simulated Body Fluid
Authors: Kang Yun Qing , Yin Guang Fu , Wang Ke Feng , Luo Lin , Yao Ya Dong
Published: March 2009

Poly-L-lactide/β-tricalcium phosphate (PLLA/β-TCP) porous scaffold fabricated by
freeze shrinking/particulate leaching was studied. The scaffold was immersed into simulated body
fluid (SBF) for 1, 2, 3 and 4 weeks and analyzed by the SEM, XRD and FT-IR spectroscopy. The
ability of inducing Ca-P formation was compared among the scaffolds with different content of β-
TCP. SEM shows a typical feature of apatite precipitation. Diffraction peak of new crystal structure
was detected by x-ray diffraction (XRD). IR Spectrum in which absorption bands arise from newly
formed groups of carbonate apatite can be seen. At the same testing point, higher density of Ca-P
crystal can be observed by SEM in scaffold with high content of β-TCP than in low group. Until 3
weeks, Ca-P individual crystal started on the wall of inner pore of pure PLLA. Porous PLLA/β-TCP
composite scaffolds also indicate good ability of Ca-P formation in vitro, the ability of which to
form apatite was enhanced by addition of each other that has different degradable mechanism.
In Vitro Study Bioactivity of HA/UHMWPE Nanocomposites
Authors: Fang Li Ming , Leng Yang , Gao Ping
Published: March 2009

Bioactivity of hydroxyapatite reinforced ultrahigh molecular weight polyethylene
(HA/UHMWPE) nanocomposites with HA volume content of 10~50 % was evaluated by simulated
body fluid (SBF) immersion. The effect of HA content on the capability for calcium phosphate (Ca-
P) induction was studied. It was found that Ca-P deposition covered the whole surface of the
composite with 30 vol. % of HA after immersion for 1 day and the layer grew to around 10 0m
thick in one-week immersion, while there was few nucleus formed for composites with HA content
lower than 30 vol. % after one-week immersion. The Ca-P structure was identified as octacalcium
phosphate (OCP) by SEM, TEM, and ToF-SIMS.
Enhanced Stability of Comb-Type Copolymer-Incorporated Liposomes
Authors: Hwang Taewon , Han Hee Dong , Jung Suk Hyun , Seong Hasoo , Cho Sun Hang , Shin Byung Cheol
Published: March 2009

To enhance the stability of liposomes in systemic circulation, a number of liposomes
modified with hydrophilic polymer such as poly(ethylene oxide) have been developed. In this study,
the comb-type copolymer was prepared as a surface modifier of liposome and the polymer was
anchored onto the lipid bi-layer via hydrophobic interaction between aliphatic chain of
phospholipids and hydrophobic chain of the polymer. The comb-type copolymer was synthesized
by radical polymerization of octadecyl acrylate (ODA), hydroxy-poly-(oxyethylene) methacrylate
(HPOEM) and 2-Hydroxyethyl methacrylate (HEMA). The structure of the comb-type copolymer
was confirmed by 1H-NMR analysis. The stability of the comb-type copolymer-incorporated
liposomes (CCIL) in serum was investigated by measuring the amount of protein adsorbed onto
liposomes. The CCIL showed a much lower amount of adsorbed protein than the other liposomes.
Those results indicated that the stability of CCIL in serum was higher than those of the other
liposomes. Thus, the comb-type copolymer composed of ODA-HPOEM-HEMA can be a promising
surface modifier for enhancement of the stability of liposomes in systemic circulation.
Evaluation of Acid-Treated Hyaluronic Acid-Based Hydrogelation
Authors: Kim Mi Sook , Choi Yoon Jeong , Kim Gun Woo , Noh In Sup , Park Yong Doo , Lee Kyu Back , Kim In Sook , Hwang Soon Jung
Published: March 2009

Though hyaluronic acid (HA)-based hydrogel has drawn great attention in biomedical
society, it’s long molecular weights sometimes have been problematic due to its difficulty in
handling. After reduction of its high molecular weight into smaller sizes with various concentrations
of hydrogen chloride solutions, its chemical and biological properties have been examined by
changes in viscosity, FTIR spectroscopy and gel permeation chromatography as well as cellular
interactions. While FTIR analysis indicated maintenance of its original chemical structures, its
viscosity has been remarkably reduced and its extent was dependent upon the employment of acid
concentrations. After controlling its molecular weight to approximately 100 kDa and coupling of
aminopropymethacrylate to the treated HA, we evaluated in vitro cellular interactions and cell
proliferations of the HA-poly(ethylene oxide) (PEO) hydrogel.