bluuebunny/crossref_metadata_2025 huggingface dataset:
Surface Charge of Bioactive Polyethylene Modified with –SO3H Groups and Its Apatite Inducing Capability in Simulated Body Fluid
Authors: Leonor Isabel B. , Kim Hyun Min , Balas Francisco , Masakazu Kawashita , Reis Rui L. , Nakamura Takashi
Published: March 2009

A bioactive polyethylene polymer substrate can be produced by incorporation of sulfonic functional groups (-SO3H ) on its surface. Variation of the surface potential of the polyethylene modified with -SO3H groups with soaking in SBF were investigated using a laser electrophoresis zeta-potential analyzer. To complement the study using the laser electrophoresis, the surface was examined by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy with an
attached energy dispersive electron probe X-ray analyser (FE-SEM/EDS). It was found that the surface potential of the polyethylene was highly negative charged after soaking in SBF for 0.5 h, increased for higher soaking times (up to 48 h), and then decreased. The negative charge of the polymer at soaking time of 0.5 h is attributed to the presence of –SO3H groups on the surface. The
initial increase in the surface potential was attributed to the incorporation of positively charged calcium ions to form a calcium sulphate, and then the subsequent decrease was assigned to the incorporation of negatively charged phosphate ions to form an amorphous calcium phosphate, which eventually transformed into apatite.
Evaluation of the Glass Bioactivity Grade by IR Analysis and the Stevels Parameter
Authors: Borrajo Jacinto P. , Liste Sara , Serra Julia , González Pio , Chiussi Stefano , León Betty , Pérez Amor Mariano
Published: March 2009

The structure of silica-based glasses consists on a disrupted network of SiO4 tetrahedra where network modifiers generate non-bridging oxygen groups (NBO), that play an important role at the initial steps of the bioactive process. Infrared spectroscopy is a sensitive technique to the presence of NBO groups and glass local structure modifications. The infrared study has been complemented with a theoretical approach using the Y Stevels parameter. Moreover, the in vitro
bioactivity of the glasses as a function of Y Stevels paremeter has been studied, which can be a finding of a predictive tool for bioactivity of glasses.
Apatite Deposition on Organic-Inorganic Hybrids Synthesized from Poly(Vinyl Alcohol) and Various Metal Oxides
Authors: You Caihong , Miyazaki Toshiki , Ishida Eiichi , Ashizuka Masahiro , Ohtsuki Chikara , Tanihara Masao
Published: March 2009

Organic polymers with ability of apatite formation in body environment are expected as novel bone substitutes having not only bone-bonding ability, i.e. bioactivity, but also mechanical performance analogous to natural bone. Several metal oxides have been found to be effective for the apatite deposition in body environment. In addition, release of calcium ions from the materials significantly enhances it. In this study, we attempted to synthesize bioactive organic-inorganic hybrids from Poly(vinyl alcohol) (PVA) by incorporation of various metal oxides and calcium salt.
Silica and molybdenum oxides were selected as metal oxides. Ability of apatite formation on the hybrids was examined in vitro using simulated body fluid (SBF, Kokubo solution). Apatite deposition were observed to occur on the surfaces of PVA/silica and PVA/molybdenum oxide hybrids in SBF, when their compositions were appropriately controlled.
A/W Bioactive Glass Particles in HEPES Solutions
Authors: Zhang Kai , Bell David C. , Francis Lorraine F.
Published: March 2009

A/W bioactive glass (BG) particles (600-1000 microns) were soaked in 0.1 M 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) solutions (0.01 g BG per 1 mL solution) at three pH ranges (acidic: 4.45-6.31, neutral: 7.45-7.64 and basic: 10.31-10.42). Crystalline calcium phosphates developed on BG surfaces after soaking in either acidic or neutral solutions. Electron diffraction (ED) results showed that whitlockite and octa-calcium phosphate (OCP) were the newly developed materials on BG in the acidic HEPES solution after soaking for 7 d and 14 d, respectively. Whitlockite also developed on the BG particles in the
neutral solution of 0.5Na-HEPES after soaking for 14 d. No crystalline materials developed on BG surfaces after soaking in the basic Na-HEPES solution up to 14 d. The results of this study demonstrated that the pH of a soaking solution strongly affect both the ions release of the A/W BG particles, and the development of crystalline calcium phosphates on BG particles.
Apatite Deposition on Polyamide Film Containing Silanol Groups in Simulated Body Environment
Authors: Kawai Takahiro , Ohtsuki Chikara , Kamitakahara Masanobu , Tanihara Masao , Miyazaki Toshiki , Sakaguchi Yoshimitsu , Konagaya Shigeji
Published: March 2009

Organic polymer coated with hydroxyapatite (so-called apatite) on its surface is a
candidate of new hybrid materials for medical applications since it is expected to show bone-bonding ability and achieve mechanical properties derived from organic substrate. We have shown that some kinds of polyamide films containing carboxyl group or sulfonic group form hydroxyapatite in the simulated body environment, when they are incorporated with calcium chloride. In the present study, the polyamide containing carboxyl groups were modified with silanol groups and its apatite-forming ability was investigated in 1.5SBF, which has ion concentrations 1.5
times those of a simulated body fluid (SBF). It was found that polyamide films modified with silanol groups showed higher ability to induce apatite on its surface in 1.5SBF than the films without the modification, when they were incorporated with calcium chloride.
Effect of Other Oxides on Solubility and Bioactivity in Calcium Phosphate Glasses
Authors: Kim Min Chul , Kim Kyoung Nam , Kim Kwang Mahn , Choi Seong Ho , Kim Chong Kwan , LeGeros Racquel Z. , Lee Yong Keun
Published: March 2009

The development of phosphate glasses for use in orthopaedic implants has attracted much interest because their chemical and physical properties make them suitable for use as bone-bonding materials. We prepared various compositions of CaO-P2O5-MO or CaO-P2O5-M2O (M: K, Li, Na, Mg, Zn) glasses to measure ion release, solubility and bioactivity. The compositions with (Ca,M)/P molar
ratio 0.6 were fixed P2O5 mol% content at 45.45 mol%, and varying MO or M2O mol% at 10, 20 and 30 mol%. Ca2+ ion release properties were investigated in 0.1M potassium acetate with pH 6 at 37oC by immersing 50 mg of powder into 100 ml of acidic buffer solution. The highest and lowest extent of released Ca2+ ion was observed for composition with 10 mol% of K2O and 30 mol% of MgO, respectively. The weight loss in distilled water at 37oC was measured. Solubility increased with
decreasing CaO content, but decreased with increasing MgO content. Bioactivity in the simulated body fluid at 37oC was measured.
Activation of Hydroxyapatite Crystal Growth on the Surface of Biomimetic Synthetic Apatites through Electrical Polarization
Authors: Sprio Simone , Celotti Gian Carlo , Landi Elena , Tampieri Anna
Published: March 2009

A series of synthetic apatites bulk samples, characterized by different atomic
substitutions were polarized by field of 1 and 2 kV·cm-1 at 300 °C. The thermally stimulated depolarization currents (TSDC) were measured and the stored electric charge density evaluated. The recent development in the synthesis of non-stoichiometric HA powders, whose chemical composition resembles that of the natural bone, is promising for the realization of improved biomimetic implants for bone substitution; therefore, electrical polarization applied on the ceramic pieces could further enhance the already strong bioactivity of these materials. The depolarization processes in the various material were evaluated by the Arrhenius’ method and
related with the corresponding chemical features; finally, SEM observations of some polarized samples immersed in SBF at 37 °C revealed a wide growth of HA particles within a few days in all the investigated materials.
Human Bone Derived Cell (HBDC) Behaviour of Sol-Gel Derived Carbonate Hydroxyapatite Coatings on Titanium Alloy Substrates
Authors: Zreiqat Hala , Roest R. , Valenzuela Stella , Milev Adriyan , Ben-Nissan Besim
Published: March 2009

Poor cell adhesion to orthopaedic and dental implants results in implant failure.
Establishing and maintaining mature bone at the bone/device interface is critical to the long-term success of the prostheses. Considerable effort has been devoted to alter the surface characteristics of these biomaterials in order to improve the initial interlocking of device and skeleton in the noncemented joint prosthesis. Previously we demonstrated that surface chemistry modification of bioceramics induced osteogenesis. In the present work, we investigate the effect of surface chemistry modification of titanium alloy (Ti-6Al-4V) with alkoxide-derived carbonate
hydroxyapatite (CHAp) using sol-gel coating methods on human bone derived cell (HBDC)behaviour. Western blotting demonstrated that sol gel coating of Ti-6Al-4V with CHAp upregulated the expression of key signalling protein Shc isoforms (p46, p52, p66) and phosphorylated Erk1/2. CHAp-modification of Ti-6Al-4V is associated with signal transduction pathways involving the key signalling protein Shc and ERK1/2 which may lead to enhanced gene expression of extracellular
matrix proteins at the skeletal tissue/device interface.
Raman Spectroscopy: Potential Tool for In-Situ Characterization of Bone Cell Differentiation
Authors: Notingher Ioan , Jell G. , Notingher P.L. , Bisson I. , Polak Julia M. , Hench Larry L.
Published: March 2009

The Classical Least Square (CLS) fitting method was used to analyze the Raman spectra of living cells with the aim of identification of new phenotype-specific spectral markers for osteoblasts. The following chemicals were used for the CLS model: DNA, RNA, serum albumin, chymotrypsin and phosphatidyl choline. In this study we analyzed primary mature osteoblasts as well as two other cell types used as potential sources of osteoblasts: embryonic stem cells and fetal bone cells. The results obtained suggest that the Raman spectra of the cell types can be well
approximated with a linear combination of the Raman spectra of the biopolymers used in the CLS model. The relative concentrations of the CLS components varied significantly between cell types, indicating that this analytical method could be used for phenotypic identification of osteoblasts.
Biocompatibility Evaluation of Zeolite Compared to Bone HA, Calcium Phosphate (Ca2PO4) and Eugenol Paste
Authors: Schainberg A.P.M. , Özyeğin Lutfiye Sevgi , Kursuoğlu P. , Valério Patricia , Goes Alfredo , Leite M. Fatima
Published: March 2009

The biocompatibility of Zeolite was evaluated, in vitro, compared to a control
and to three different biomaterials: hydroxyapatite from bovine bone, calcium
phosphate and a commercial eugenol paste. The Zeolite did not affect cellular
proliferation neither the alkaline phosphatase and collagen production. The apoptosis
index of the zeolite groups were similar to control and optical microscopy observations did not show any morphological cell change, except the some cytoplasmatic vacuole formation.
The Influence of Pre-Incubation Treatment in the In Vitro Biological Performance of Degradable CaO-P2O5 Glass Ceramics
Authors: Dias A.G. , Lopes M.A. , Santos José D. , Fernandes Maria Helena F.V.
Published: March 2009

Based upon the CaO-P2O5 glass system, two glass ceramics were prepared in the meta-, pyro- and orthophosphate regions. The present work describes results concerning the biological activity of MT13B (45CaO-37P2O5-5MgO-13TiO2, in mol %) and MK5B (45CaO-45P2O5-5MgO-5K2O, in mol %) using MG63 osteoblast-like cells cultured for 6 days. The influence of a 24h pretreatment
with culture medium before cell culture was also evaluated (MT13Bi; MK5Bi). Both “as received” and pre-treated material samples supported cell growth, which increased with the culture time. Pre-treatment resulted in an increase of adhered cells on both materials (day 1). Throughout the culture time (days 3 and 6), MT13Bi presented higher cell numbers than that of MT13B, but no differences were found between MK5Bi and MK5B. In addition, cell growth was significantly lower in the K-containing glass ceramic in both experimental situations comparing with Ticontaining glass ceramic. SEM and confocal microscopy observation showed that cell adhesion and spreading were hampered on MK5B samples. Evident macroscopic and microscopic surface instability was observed on this material with simultaneous dissolution/precipitation processes. By contrast, MT13B presented a relatively stable surface throughout the culture time. Results suggest that the pre-incubation with culture medium improves the adhesion of the osteoblast cells to both
glass ceramics and that the high degradation rate of MK5B hinders the in vitro biological performance of this material.
Comparison of Validity between WST-1 and MTT Test in Bioceramic Materials
Authors: Kim Kwang Mahn , Lee Sang Bae , Lee Se Ho , Lee Yong Keun , Kim Kyoung Nam
Published: March 2009

Cytotoxicity test was essential for the pre-clinical evaluation of bioceramics. Proliferation assays such as MTT, XTT and WST-1 were commonly used for measuring biocompatibility. WST-1 was more convenient than MTT because of its water-solubility and storage condition. The calcium phosphate glass and β-TCP have been used for bone substitute, and some magnetic ferrites have been used for hyperthermic treatment. L929, mouse fibroblast cell, was the representative cell-line for in vitro biocompatibility test. The extracts of test samples were prepared by ISO10993-12:2002. The biocompatibilities of the extracts were measured by MTT and WST-1 assay and their pH were measured with pH meter. The cellular survival rate of CPG was the lowest and the results of the WST-1 test showed results similar to those of the MTT test. Thus, proliferation assays using WST-1 may be conveniently and routinely applicable to pre-clinical evaluation of bioceramics.
Genotoxicity Effects of Ceramic Coatings Applied on Metallic Substrates Using Single Cell Gel Electrophoresis Assay In Vitro
Authors: Peláez Alejandro , García Claudia P. , Pareja A. , Márquez M.E. , Toro Alejandro , Castañeda R. , Abad Pablo
Published: March 2009

Sol-Gel coatings are a good choice for protection and bioactivation of metals used as dentistry and standard surgical implant materials. These films should both prevent degradation of the substrates by wear or corrosion, and bioactivate the material for inducing the formation of a hydroxyapatite (HA) rich layer onto the material surface, thereby permitting a natural bonding to living tissues. The aim of this work was to estimate the clastogenicity in vitro by Single Cell Gel lectrophoresis
Assay (SCGE) or “comet” assay of coatings of TiN applied by magnetron sputtering and of hybrid layers obtained by Sol-Gel containing glass, glass-ceramic and HA particles on stainless steel AISI 304.
Six test specimens were prepared: AISI 304 Stainless Steel coated with an hybrid silica single film (SF), applied by sol-gel process, AISI 304 SS coated with double film with bioactive glass (DFG), glass-ceramics (DFGC) and HA (DFHA) particles, AISI 304 SS coated with TiN multi films (MFTiN) applied by PVD and bare AISI 304 SS (304SS). Significantly lower DNA migration (p>0.005) was observed in the cells of the cultures corresponding to the samples coated with SF, DFG, DFGC, DFHA and MFTiN respect to the bare 304 SS. The comparison between negative control and the same coated samples did not reveal any
statistically significant difference (p>0.005) in clastogenicity in vitro evaluated by SCGE.
Effects of Ca-Containing Phosphate Glasses on T Lymphocytes In Vitro
Authors: Kesisoglou A. , Knowles Jonathan C. , Olsen I.
Published: March 2009

Calcium phosphate-based glasses (PG) are of interest as both scaffold and delivery materials for tissue rebuilding because of their chemical similarity to bone. Since it is essential that these materials exhibit local and systemic biocompatibility and do not adversely affect host tissues, the present study was undertaken to examine the effects of PG containing different amounts of Ca on human T lymphocytes in vitro. This was carried out by measuring the effects of extracts of the
PG on the direct and mitogen-induced activation of T cells from human peripheral blood, as well as assessing CD4 and CD8, surface antigens which define T-helper and T-suppressor cells, respectively. The results showed that DNA synthesis by resting T lymphocytes was unaffected by all the PG. However, extracts of the PG containing 24 mol% of Ca caused a very marked inhibition of mitogen-induced T cell activation. This PG also reduced both the resting CD4+ and CD8+ T cells, as well as activated CD8+ cells. In contrast, high Ca-PG significantly augmented DNA synthesis by mitogen-activated T cells. These experiments show that PG containing differing levels of Ca can have pronounced and differential effects on the activation and function of T lymphocytes in vitro.
Bisphosphonates Incorporated on a Ca-P Biomimetic Coating Produced by a Sodium Silicate Based Methodology Stimulate Osteoblastic Activity
Authors: Oliveira A.L. , Santos M.I. , Pedro A.A. , Reis Rui L.
Published: March 2009

In the present study sodium clodronate, a well known therapeutic agent from the family of bisphosphonates (BP) was incorporated in an apatite coating, previously formed on the surface of a starch based biomaterial by a sodium silicate methodology, as a strategy to develop a site-specific drug delivery system for bone tissue regeneration. The effects on the resulting apatite coatings were
evaluated in terms of morphology, chemistry and structure. As a preliminary approach, this first study aimed at evaluating also the effects of this BP on the viability, growth and function of a human osteoblast cell line, since there is still little information available on the interaction between BPs and this type of cells.
In Situ Monitoring of Chondrocyte Response to Bioactive Scaffolds Using Raman Spectroscopy
Authors: Jones Julian R. , Vats Archana , Notingher Ioan , Gough Julie E. , Tolley Neil S. , Polak Julia M. , Hench Larry L.
Published: March 2009

Septal cartilage is widely used for the repair of soft tissue defects in the head, neck and nose. Tissue Engineering techniques are being investigated to create cartilage in vitro by seeding appropriate cells on resorbable scaffolds. In this study, human chondrocytes were cultured on macroporous bioactive glass foam scaffolds. The aim was to investigate how Raman spectroscopy could be used as a non-invasive technique to monitor the response of chondrocytes to a 3D scaffold in real time. The spectra were compared to scanning electron microscope (SEM) micrographs and
immunohistochemistry results.
Protein Loading and Solubility of Apatite Hydrogel
Authors: Yokogawa Yoshiyuki , Shiotsu Yoshikazu , Nagata Fukue , Watanabe Makoto
Published: March 2009

Protein loading on apatite hydrogel cake and its solubility was studied. A mixture of
di-sodium hydrogen phosphate dodeca-hydrate and calcium chloride di-hydrate was dissolved in water, and kept at room temperature for 2 weeks in air or N2 atmosphere to make apatite hydrogel. The obtained apatite hydrogel contains carbonate ions, and its carbonate content strongly affect the aggregation of particles. With maturation period, the particle size of apatite hydrogel decreased in air, but increased in N2 atmosphere. The quantity of loaded Cytochrome C in apatite hydrogel formed in air was 0.490 wt%, while that in apatite hydrogel formed under N2 atmosphere was 0.305 wt%. But the quantity of loaded albumin in apatite hydrogel formed in air was less than that in apatite hydrogel formed under N2 atmosphere. The difference may be due to the relationship between isoelectric point
of protein and apatite hydrogel. The apatite hydrogel containing protein was dried for 4 days in air at 40 % of relative humidity to make cakes, and the cakes were immersed in pure water or PBS solution. The dried specimen slowly dissolves in aqueous solution, and the decrease in weight of apatite cake prepared from hydrogel formed in air was larger than that from hydrogel formed under N2 atmosphere compared to the dissolved apatite, the released protein was less, which may be associated with recrystallization of the apatite hydrogel.
A Method for Simultaneously Precipitating and Dispersing Nano-Sized Calcium Phosphate Suspensions
Authors: Lemos A.F. , Rebelo A.H.S. , Rocha J.H.G. , Ferreira José Maria F.
Published: March 2009

Stable and relatively concentrated aqueous suspensions of nano-sized stoichiometric hydroxyapatite could be prepared by a precipitation method in the presence of suitable surface active agent (SAA). The method includes the precipitation, vacuum filtration and washing of the precipitated powders, followed by re-dispersion. It could be concluded that the added amount of the SAA should be enough to cover the primary particles surface, and that washing should be better
carried out using a SAA solution. The method developed enables the precipitation of the powders and the preparation of suspensions, while significantly shortening the overall time required for colloidal processing consuming.
In Vitro Mesenchymal Stem Cell Culture Using Calcium Phosphate Glass Scaffold
Authors: Kim J. , Ryu J.K. , Kim Min Chul , Kim Yeon Ung , Choi Seong Ho , Kim Chong Kwan , Kim Kyoung Nam , Kim Kwang Mahn , LeGeros Racquel Z. , Lee Yong Keun
Published: March 2009

The purpose of this study was to evaluate the cell affinity of calcium phosphate glass
scaffold in the system of CaO-CaF2-P2O5-MgO-ZnO, which is already reported that promoted the bone-like tissue formation in vitro and formed new bone in Sprague-Dawley rats. We prepared calcium phosphate glass saffolds with three-dimensionally interconnected pores of 200~500 µm. Commercial HA scaffold was employed as a control in this study. Bone marrow cells were collected from the healthy human donors and cultured within the prepared scaffolds. After 2, 4, 6, and 8 weeks, hMSCs/scaffold were fixed and stained with hematoxylin and eosin. hMSCs were continuously proliferated both in the experimental and control groups at every incubation period. The number of cells was higher in the experimental group than that of the control group, however, there was no significant difference (p>0.05). Extracellular matrices could be observed at the 2nd and 4th days in the
experimental and control groups, respectively. The extracellular matrices were more abundant in the experimental group at all periods. The prepared calcium phosphate glass scaffolds are expected effective in bone tissue engineering.
A New Synthetic Route to Calcium Polyphosphates
Authors: Jackson Lauren E. , Wright Adrian J.
Published: March 2009

This study describes the use of flux methods as a novel synthetic route to some known and new calcium polyphosphates, with a view to developing new biomaterials. Calcium acid pyrophosphate, CaH2P2O7, which is a known precursor in the preparation of many other calcium polyphosphates, has been synthesized as a pure crystalline phase in a single step synthesis at temperatures between 190-250 °C. Reaction temperatures between 250 and 400 °C led to the synthesis of γ-Ca(PO3)2, a previously uncharacterised polymorph of calcium metaphosphate.
Lattice parameters of a = 10.3682(1) Å, b = 9.5001(1) Å, c = 9.5552(1) Å, with β angle of 93.45(4)° were obtained from powder X-ray diffraction data. A subsequent increase in reaction temperature to 550 °C was found to produce a calcium polyphosphate glass. A detailed study of thermal stability of CaH2P2O7 was also performed to determine phase stability and decomposition pathways.
Amorphous Calcium Phosphate Based Polymeric Composites: Effects of Polymer Composition and Filler's Particle Size on Composite Properties
Authors: Skrtic Drago , Lee S.Y. , Antonucci Joseph M. , Liu D.W.
Published: March 2009

This study explores how a) the resin grafting potential for amorphous calcium phosphate (ACP) and b) particle size of ACP affects physicochemical properties of composites. Copolymers and composites were evaluated for biaxial flexure strength (BFS), degree of vinyl conversion (DC), mineral ion release and water sorption (WS). Milled ACP composites were superior to unmilled ACP
composites and exhibited 62 % and 77 % higher BFS values (dry and wet state, respectively). The average DC of copolymers 24 h after curing was 80 %. DC of composites decreased 10.3 % for unmilled Zr-ACP and 4.6 % for milled Zr-ACP when compared to the corresponding copolymers. The WS increased as follows: copolymers < milled Zr-ACP composites < unmilled Zr-ACP composites. The levels of Ca and PO4 released from both types of composites increased with the
increasing EBPADMA/TEGDMA ratio in the matrix. They were significantly above the minimum necessary for the redeposition of HAP to occur. No significant consumption of released calcium by the carboxylic groups of methacryloxyethyl phtahalate (MEP) occurred at a mass fraction of 2.6 % of MEP in the resin. Improvements in ACP composite’s physicochemical properties are achieved by fine
tuning of the resin and improved ACP’s dispersion within the polymer matrix after ball-milling.
Lignin-Hydroxyapatite/Tricalcium Phosphate Biocomposites: SEM/EDX and FTIR Characterization
Authors: Mansur Herman S. , Mansur Alexandra A.P. , Bicallho Sheyla M.C.M.
Published: March 2009

In the present work, a novel biocomposite has been developed based on lignin (Lig) and HA/b-TCP bioceramic materials. The Lig/HA and Lig/b-TCP systems were investigated by Scanning Electron Microscopy coupled to EDX microprobe (SEM/EDX). Lignin is a lignosulfonate natural polymer with complex random coupling and the exact chemical structure is yet unknown. FTIR spectroscopy is an important tool for lignin characterization based on several major vibration
bands associated with generally found chemical groups. Consequently, FTIR spectroscopy was used to evaluate the chemical functionalities and major components present in the material. SEM photomicrographs of biocomposites Lig/HA and Lig/b-TCP have shown uniform dispersion of the natural polymer binder in the bioceramic matrix. Also, chemical composition obtained by EDX
spectra have indicated lignin evenly distributed in the HA and b-TCP compounds. Novel biocomposites based on lignin/HA and lignin/b-TCP were developed with porosity ranging from 50 to 100 µm. These results have confirmed the high potential application of lignin as a non-toxic natural polymer binder to be used as 3D scaffold template for biomedical applications.
Physical Properties of Composite Membrane Containing Apatite and Poly-Lactic Acid /Poly-Glycolic Acid Copolymer In Vitro
Authors: Watanabe T. , Ban Seiji , Itoh Toshiki , Tsuruta Shozo , Kawai Takahiro , Nakamura Hiroshi
Published: March 2009

The purpose of this study was to evaluate the physical properties of the composite
membrane before and after soaking in simulated body fluid (SBF) and discuss both degradation and maintenance of their properties. Before and after soaking in SBF, some deposits were found on the preexisted apatite crystals, and Ca and P were mainly detected by energy dispersive X-ray analyzer (EDX). Our results suggest that the composite membrane consisting of apatite and the biodegradable PLGA copolymer would have excellent biocompatibility and maintain adequate
physical properties for in vivo use.
Interfacial Interactions between Liquid New Biocompatible Model Glasses and Solid Metallic and Ceramic Substrates Used in Biomedicine
Authors: Key I.A. , Pina S. , Agathopoulos Simeon , Tulyaganov D.U. , Ferreira José Maria F.
Published: March 2009

In the framework of producing new composite biomaterials, this study investigated the interfacial interactions between molten brand new biocompatible glasses with model formulations and Ti, hydroxyapatite, zirconia and a CrNi-steel. Analysis, by grouping the results of each particular substrate, indicates that Ti reduces the molten glass-oxides, HA tends to diffuse with them, zirconia grain-boundaries are vulnerable towards them, and Cr-Ni-steel very poorly adhere to them. Analysis, by grouping the results of each particular glass, indicates that the matching of their
expansion coefficient with that of substrate and crystallization affect the formation of continuous or cracked interface. Viscosity and surface tension of glasses determine wettability. Wettability is not however determinative index of evaluating the quality and the strength of the resulting interfaces.
Preparation and In Vitro Evaluation of Radioactive Calcium-Phosphate Micron-Sized Particles for Internal Radiotherapy of Hepatoma
Authors: Chou Fong In , Hsieh M.F. , Chung Ren Jei , Liu H.S. , Chin Tsung Shune , Liu W.Y. , Chi C.W. , Liu R.S.
Published: March 2009

Radiotherapy is one of the effective treatments for cancers. This study presents a potential internal radiotherapy drug, radioactive calcium-phosphate micron-sized particles (RCPMP). The interaction of calcium-phosphate micron-sized particles (CPMP) with hepatoma cells and the cytotoxicity of RCPMP to hepatoma cells were evaluated. The CPMP having the eutectic composition of the CaO-P2O5 system (CaO-47wt% P2O5) was prepared and subsequently subjected to
neutron irradiation in a nuclear reactor to yield RCPMP. The main nuclide in the RCPMP was P-32. RCPMP could be stably retained in a serum and culture medium. These CPMP had a high affinity with HepG2 human hepatoma cells. Cells climbed onto the larger CPMP particles, surrounding and embedding them within several days. The submicro-sized CPMP were endocytosed and retained in HepG2 cells. The dose dependent killing effect was obtained in RCPMP treated HepG2 cells. Cells were killed and detached from the flask with little morphological changes under a high dosage of RCPMP treatment. Meanwhile, treating HepG2 cell cultures with a lower dosage of RCPMP led to morphological changes before cell death. This RCPMP was biocompatible and had high killing effect on hepatoma cells.
Indentation Testing of a Bone Defect Filled with Two Different Injectable Bone Substitutes
Authors: Wang Jian Sheng , Tanner K.E. , Abdulghani Saba , Lidgren Lars
Published: March 2009

Injectable bone substitutes (IBS) based on calcium phosphate (CaP) and/or calcium sulphate (CaS) are used as fillers in bone defects to stimulate bone integration and allow mechanical loading. Two types of IBS, IBS-1 is CaP+20%CaS and IBS-2 is CaS+40% hydroxyapatite, were investigated. The materials were injected into holes in the femur and tibia in rabbits. After 10 weeks the femora were
subjected to indentation testing and tibiae were prepared for histology evaluation. IBS-1 lead to an higher indentation load compared to control, that is no material inserted, while IBS-2 showed no significant difference between material and control. Histology showed that with IBS-1, the bone penetrated into and integrated with the material in the defect. With IBS-2, new bone grew into the outer 0.5-1.0 mm. The materials could be used for different indications, such as to support fracture healing or in contained cavities.
Effect of Glass Filler Content on Hydrophilic Addition Silicone Impression Materials in Dentistry
Authors: Kang J.K. , Lee Yong Keun , Kim Kwang Mahn , Kim Kyoung Nam
Published: March 2009

Dental impression materials are used to register or reproduce the form and relationship of the teeth and oral tissues. They should not be torn when removing from the wet mouth after setting. Nowadays, silica is widely used as filler to overcome the low mechanical strength of the dental impression materials. The purpose of this study was to synthesize high strength glass in the system of
MgO-CaO-Al2O3-SiO2 and investigate its usefulness according to ISO standard after mixing with addition silicone. Commercial products, Contrast, Examix, Express, and Perfect-F were selected as control group. When the prepared glass filler was introduced in addition silicone impression material, tear strength was drastically increased significantly than that of the control group, keeping the consistency. All experimental groups showed higher tear stength than that of control groups. As the
amount of filler content increases, tear strength was increased. Strain in compression, recovery from deformation, and linear dimensional change were satisfied the ISO standard either all the experimental or control groups. Therefore, calcium-substituted magnesium aluminosilicate glass in the system of 12.5MgO-17.5CaO-20Al2O3-50SiO2 is expected the useful filler in the light body of addition silicone impression materials.
Increased Osteogenesis Elicited by Boron-Modified Bioactive Glass Particles in the SiO2-CaO-P2O5-Na2O System: A Histomorphometric Study in Rats
Authors: Gorustovich A. , Guglielmotti M.B. , Porto López J.M. , Cabrini R.L.
Published: March 2009

The effect of boron-containing bioactive glass (BG) particles in the SiO2-CaO-P2O5-Na2O system on the bone formation was studied by histologic, histomorphometric and microchemical evaluation. Wistar rats were used throughout. Under anesthesia, 45S5 BG particles were placed inside the medullary compartment of the tibia (Control), while in the contralateral tibia (Experimental) 45S5.2B BG particles were implanted. The animals were sacrificed 15 days postimplantation. The tibiae were resected, radiographed, and embedded in methyl methacrylate resin. Sections were stained with toluidine blue and analyzed by light microscopy, backscattered scaning electron microscopy and energy-dispersive X-ray analysis
(EDX). Histomorphometric determinations were performed. Light microscopy of the histologic sections showed lamellar bone formation surrounding both biomaterials. The histomorphometric study revealed a statistically significant increase in bone tissue around 45S5.2B BG particles.
EDX of newly formed bone tissue showed a rise in the Ca:P ratio when 45S5.2B BG particles were employed. The results described in the present study reveal that this boron-containing bioactive glass may be used as scaffold for bone tissue regeneration.
All-Ceramic Fixed Partial Denture Cores Prepared Using Water-Based Alumina Tapes
Authors: Park Il Seok , Choi Se Young , Lee Myung Hyun , Kim Dae Joon , Han Jung Suk
Published: March 2009

Aqueous-based alumina tape, prepared using acrylate emulsion binder, was employed to form 3-unit all-ceramic anterior fixed partial denture core structures. Formability, linear shrinkage, and strength of the tape were optimized by adjusting tape composition to a/(a+b+p)=0.84 and b/(b+p)=0.5. Marginal fitness of the core framework was acceptable for clinical applications when more than two points on lingual side of core structure were placed to touch a plate during sintering.
The 3-unit all-ceramic anterior fixed partial denture utilized ceramic tape has functioned successfully for 3 years without any loss of structural integrity and esthetics.
Bioactive Cyanoacrylate-Based Filling Material for Bone Defects in Dental Applications
Authors: Park Kyeong Jun , Park Ji Ho , Lee Sang Bae , Lee Doug Youn , Kim Kyoung Nam , Kim Kwang Mahn
Published: March 2009

We tried to prepare a new filling material for bone defects using β-Tricalcium phosphate (β-TCP) particles and Histoacryl®. The aim of this study was to evaluate physical and bioactive properties of cyanoacrylate-based filling materials for bone defects in the dental field. The shear bond strength values of the Histoacryl® and β-TCP/ Histoacryl® compounds stored in double-distilled
water decreased with the increase of the amount of added β-TCP. The temperature change of the β-TCP/ Histoacryl® compounds during polymerization decreased compared to that of the Histoacryl®. The cytotoxicity of the filling materials decreased when the amount of added β-TCP was increased. In the evaluation of bioactivity, hydroxyapatite (HA) was precipitated on the surface and inner space of the porous filling material 4 weeks after immersion in SBF. This precipitation of HA on the surface of the filling material was also confirmed in the XRD result. These results indicate that our novel β-TCP/Histoacryl® compounds have the potential to serve as filling materials for bone defects in the dental field.
Preformed Laminating Veneer Porcelain Using Paste System for Fabrication of PFM Crowns
Authors: Lee Myung Hyun , Han Jung Suk , Kim Dae Hyun , Oh Nam Sik , Kim Hyeong Seob
Published: March 2009

Feldspathic porcelain paste system using organic vehicle was prepared and applied to fabricate the porcelain fused to metal fixed partial denture. The mean linear fired shrinkage of paste porcelain system was 15.2% that is 0.8% lower than that of conventional build-up method. The color difference between two methods (E*) was 0.156. Mean biaxial flexural strength of sintered preformed laminating porcelains of this system and conventionally build-up porcelains were 74±3
and 70±4 MPa respectively. There was no deterioration of physical properties of feldspathic porcelain system by introducing organic vehicle, and this new build-up method can be applied to fabricate the porcelain fused to metal restorations.
SPS Processing and Superplastic Deformation of Silicon Nitride Based Ceramics
Authors: Peng Hong , Shen Zhi Jian , Nygren Mats
Published: March 2009

Recently we have introduced a novel processing concept of sialon components
implying that an extra liquid phase that is thermodynamically compatible with sialon phases is introduced by increasing the O/N ratio in the general formula (Yb+Y)xSi12-(3x+n)Al3x+nOnN16- n while keeping constant the Yb, Y, Si, and Al proportions. By increasing the oxygen content from its stoichiometric value of 5.16 to 15 eq%, a series of powder mixtures were prepared and their overall compositions are located slightly above the homogeneity region of the a-
sialon phase. These compositions were consolidated to full densities by hot pressing (HP) and Spark Plasma Sintering (SPS), respectively. The sintering kinetics in the HP and SPS units is compared. The grain growth kinetics were investigated both by post heat-treatment of SPS pre-consolidated monophasic a-sialon bodies consisting of sub-micron sized equiaxed grains in a conventional graphite furnace using extended holding times (hours) and in the SPS
apparatus rapidly heated exceeding the temperature threshold of grain growth and using short holding times (minutes). Post heat treatment in the SPS apparatus yielded in-situ reinforced microstructures no matter if an additional liquid/glass was involved or not while corresponding microstructures could only be obtained for non-stoichiometric compositions by post heat treatment in the graphite furnace. The grain growth kinetics is discussed in terms of static and dynamic ripening mechanisms. We have recently shown that the ductility of covalent bonded silicon nitride based ceramics is dramatically enhanced in presence of a pulsed electric field. Compressive strains rates in the range of 10-2 s-1 can easily be achieved
at T ³ 1500oC. The enhanced ductility is explained by that the electric field induces motion of charged species present in the grain boundary glassy/liquid phase that in turn promotes grain sliding along the grain boundaries.
Microwave Sintering and Infiltration of Highly Porous Silicon Nitride Ceramics to Form Dense Ceramics
Authors: Willert-Porada Monika , Grosse-Berg Jens , Sen Ilker , Park Ho Seon
Published: March 2009

A new processing route for porous b-Si3N4 –ceramics suitable as substrates for Si3N4 functionally graded materials, FGM`s with an environmental barrier coating, EBC, is described. Such materials could be useful for operation at temperatures up to 1650°C in combustion engines, where oxidation and corrosion under hydrothermal conditions cause severe damage of known dense Si3N4-ceramics. The new process is based on microwave sintering of a-Si3N4–Yb-silicate green
parts to obtain up to 60% open porous b-Si3N4 pre-forms equilibrated at high temperature with respect to the RE-silicate content, followed by Si-melt infiltration. A sufficient wetting by molten silicon is achieved by coating the inner surface of the porous pre-form with amorphous carbon prior to infiltration. The influence of different green processing parameters and different heating methods - microwave heating and conventional heating – on the porosity of the pre-form is reported.
Infiltration is performed by microwave heating of the carbon coated pre-forms, whereas for nitridation both heating processes are combined.
Fabrication and Strength Properties of LPS-SiC Ceramics
Authors: Park Yi Hyun , Kim Dong Hyun , Yoon Han Ki , Kohyama Akira
Published: March 2009

SiC materials have been extensively studied for high temperature components in advanced energy system and advanced gas turbine. SiCf/SiC composites are promising for various structural materials. But, high temperature and pressure lead to the degradation of the reinforcing fiber during the hot pressing. Therefore, reduction of the process temperature and pressure is key requirements for
the fabrication of SiCf/SiC composites by hot pressing method. In the present work, monolithic LPS-SiC was fabricated by hot pressing method at various temperatures. The starting powder was high purity β-SiC nano-powder with an average particle size of 30nm. Compositions of sintering additives were Al2O3 / Y2O3 = 0.7 and 1.5 (wt.%). Monolithic LPS-SiC was evaluated in terms of sintering density, micro-structure, flexural strength, elastic modulus and so on. Sintered density,
flexural strength and elastic modulus of fabricated LPS-SiC increased with increasing the process temperature. Particularly, relative density of LPS-SiC fabricated at 1820oC with additive composition of Al2O3/Y2O3=1.5(wt.%) was 95%. Also, flexural strength and elastic modulus were 900MPa and 220GPa, respectively. In the fracture surface of this specimen, the size and shape of SiC grains grew up and changed. Also, tortuous crack paths and occurrence of interfacial debonding were observed.
Synthesis of Porous MoSi2 Material Fabricated by SHS (Self-Propagating High Temperature Synthesis) Process
Authors: Song In Hyuck , Kim Do-Wan , Yun Jung Yeul , Kim Hai Doo
Published: March 2009

In this study, SHS process has been employed to fabricate porous MoSi2 material with electric-resistive heating capability through the control of pore size. The preform for SHS reaction was consisted of molybdenum powder with different sizes and silicon powder with different contained quantity. The size of the MoSi2 particles thus formed was determined by the generated heat of combustion, not by the size of molybdenum powder. However, the pore size of MoSi2 composite was proportional to the particle size of molybdenum powder. That is, the coarser the molybdenum powder used, the larger the formed pore size. Based on these results, the porous MoSi2 composite could be fabricated with a desired pore size. By orienting the porous molybdenum disilicide-based material in the form of pore size gradient, porous materials used for filters with improved dirt-holding capacity can be manufactured.
Influence of Amount of Nitrogen on Crystallisation of Y-SiAlON Glasses: In Situ XRD Analysis
Authors: Dolekcekic E. , Pomeroy Michael J. , Hampshire Stuart
Published: March 2009

Y-SiAlON glasses of composition 36.5 Y: 42.3 Si: 21.2 Al with different amounts of N (0, 5, 8, 15 and 22 in e/o) were produced by melting appropriate mixtures of powders under flowing nitrogen at 1715°C. This composition is known to give B-phase (Y2SiAlO5N) on crystallisation at temperatures below 1050°C. In this work, the effect of nitrogen in the starting glass composition on the crystalline phases formed is discussed. High temperature in-situ XRD analysis was performed on powdered glass samples up to 1150°C by using a Philips X’pert PRO MPD (Multi Purpose Diffractometer) with a HTK1200 Oven Camera (Anton Paar, Austria). As expected, the results show that different nitrogen contents affect the crystalline phases formed. In all glasses, yttrium apatite silicate forms first, followed by crystallisation of B-phase. The phase transformation from B-phase to Iw-phase (Y3Si2Al[O,N10] i.e. 10 e/o N) takes place at relatively low temperatures (1050°C) for the lower nitrogen containing samples (5 and 8 e/o), whereas, the transformation does not take place for the glasses with higher nitrogen contents even at the maximum temperature studied (1150°C). This work also confirms that there is a correlation between the temperature where the first crystals appear and the amount of nitrogen in the starting glass.
Construction of Biodegradable Multilayer Films via Layer-by-Layer Self-Assembly as Gene Delivery System
Authors: Ren Ke Feng , Ji Jian , Shen Jia Cong
Published: March 2009

Films composed of alternating layers of protamine and DNA were constructed using the layer-by-layer method on quartz and subsequently studied the enzymic degradation in vitro. UV-visible spectrometry measurement indicated the uniform assembly of Protamine/DNA multilayer films. UV-visible spectrometry and fluorescence spectrometry results revealed that the Protamine/DNA multilayer films were in vitro enzymic biodegradable. The novel biodegradable multilayer of Protamine/DNA may have great potential for gene therapy applications in tissue engineering, medical implant etc.
Electrochemical Preparation of Ordered Nano HAp Coatings on Ti Substrate and In Vitro Study on Its Bioactivity
Authors: Zhuang Yan Yan , Hu Ren , Shi Hai Yan , Tang Jian , Lin Chang Jian
Published: March 2009

The HAp coatings with various surface morphologies were electrochemically deposited on titanium to improve its bio-properties. We compared the bio-properties for the different surface morphology coatings on titanium through a detailed surface characterization and upon in vitro cellular response of osteoblast-like cells MG63. The results of in vitro cellular response indicated that the uniform porous morphology of HAp layers on titanium exhibited higher bioactivity than the needle-like ones.
The Influences of β-Glucan Associated with BMP-7 on MC3T3-E1 Proliferation and Osteogenic Differentiation
Authors: Lee D.H. , Han Dong Wook , Park B.J. , Baek Hyun Sook , Takatori K. , Aihara M. , Tsubaki Kazufumi , Park Jong Chul
Published: March 2009

b-glucan, an immunomodulator, can selectively enhance the immunobiological
activities of neutrophils and macrophages without stimulating proinflammatory cytokine production. Biologic response modifiers, like beta-glucan, will modulate immunity, modify neoplastic disease and increase resistance to microbial challenge. Therefore, beta-glucan polymers can be applied in bone induction and regeneration model and have a possibility of association with bone morphogenetic protein (BMP) because of tissue-regenerative and antimicrobial effects of those polymers. In this report, we studied an E. coli expression system for BMP-7 production and the biological activities of b-glucan associated with BMP-7. The proliferation of MC3T3-E1 osteoblastic cells was enhanced by treatment with Aureobasidium b-glucan, while neither mushroom b-glucan nor barley b-glucan increased the cell proliferation. Mushroom b-glucan alone or associated with BMP-7 increased alkaline phosphatase (ALP) activity of MC3T3-E1 cells, one of the osteoblast phenotype markers, but the other b-glucans did not affect ALP activity
of the cells. In mineralization assay, a highly significant increase in nodular staining was observed in cultures treated with both mushroom and Aureobasidium b-glucans in the presence of BMP-7 compared with nontreated controls, while barley b-glucan showed a significant decrease in nodule number compared with cultures treated only with BMP-7.