bluuebunny/crossref_metadata_2025 huggingface dataset:
Study of Effect on Cell proliferation and Hemolysis of HAP and TCP Nanometer Particles
Authors: Huang Zhe Wei , Ding Ting Ting , Sun Jiao
Published: October 2011

Hydroxyapatite (HAP) and tricalcium phosphate (TCP) nanoparticles (NPs) are in current use covering a wide range of medical applications, hence, it is indispensable to study the potential side effect acting on living organism, and to figure out the biocompatibility evaluation model of nanoparticles for standardization and methodology. In the present study, HAP and TCP NPs were selected and their diameters were within 30-80nm. Cytotoxicity in vitro was analyzed by agar overlay and direct contact exposure test was conducted to evaluate potential toxicity to SD rat macrophages, and hemolysis test of NPs was performed in compliance with ISO 10993-12 guidelines. The results showed that both HAP and TCP NPs could inhibit proliferation of macrophages when their concentration was reached to 20 µg/ml, and the extent of haemolysis would be increased more than 5% while 1000µg/ml NPs were contacted with rabbit blood cells. Furthermore, TCP NPs could induce obvious hemolysis reaction and inhibit proliferation of macrophages compared with group of HAP NPs at the same concentration.
Direct Reactive Compatibilization of GMA on PE/Wood-Flour Composite
Authors: Li Yue Wen , Chen Xin Hua
Published: October 2011

Reactive compatibilization between high-density polyethylene(HDPE) and wood-flour was achieved via direct reactive extrusion of glycidyl methacrylate(GMA), initiator, HDPE and wood-flour. Impact rupture surface of the composite was observed by scanning electron microscope(SEM), and its load deformation temperature(HDT) and mechanical properties were tested. Effect of GMA dosage and extrusion temperature on reactive compatibilization of the composite was analysed. The result indicated that the anchoring strength of interface in the composite was obviously strengthened, and its HDT, tensile strength, flexural strength, notched impact strength and elongation at break of the composite were distinctly improved due to the addition of GMA and dicumyl peroxide(DCP). When the composite was extruded at 180°C, the peak values of its HDT, tensile strength, flexural strength, elongation at break and notched impact strength respectively were 84°C, 40Mpa, 45Mpa, 11% and 6.6KJ.m-2, which respectively increased by 17°C, 74%, 36%, 83% and 69% than that of the composite without reactive compatibilization, and when the composite was extruded at 190°C, the peak values of its HDT, tensile strength, flexural strength, elongation at break and notched impact strength respectively were 84°C, 40Mpa, 44Mpa, 11% and 6.6KJ.m-2, which respectively increased by 20°C, 60%, 26%, 83% and 83% than that of the composite without reactive compatibilization. When GMA usage increased, the HDT and mechanical properties of the composite increased first, then descended, and the optimum usage of GMA was 1wt%-3wt%.
Effect of Attenuation on Four-Wave Mixing Generation
Authors: Nizam M.A. , Arsad N. , Abdul Razak Hanim , Shaari S. , Annuar A.E. , Nasir M.Z.A. , Rashid A.Z.A.
Published: October 2011

Four-wave mixing (FWM) phenomenon can be produced by using a different refractive index of the optical fiber in an erbium doped fiber laser system. In our study, we used a 20 meter length of Photonics crystal fiber (PCF) to generate multiwavelength signals. Variable optical attenuator is employed in the setup to study its effect on the output signals. Results show that uniform signals were obtained by using the VOA to suppress other modes of wavelengths which occurred before placing the VOA. New lasing wavelength at 1530.445 nm, 1531.450 nm, 1531.960 and 1532.415 nm were produced uniformly.
Landfill Clay Barrier: Fibre Reinforcement Technique
Authors: Plé Olivier , Ngoc Hà Lê Thi , AbuAisha Murad S.
Published: October 2011

Landfills come with a cover barrier which includes a compacted silty clay liner essential to safety on site. However this barrier encounters problems, especially those related to the differential settlement, which may cause stress in the clay layer leading to the development of cracks. Generally speaking, tensile stress damage and shearing are observed on the cap cover. Due to the weak mechanical performance of the clay layer it was proposed to add polypropylene fibre reinforcement. Direct tensile tests and compression tests under low confinement were carried out on unreinforced and reinforced soils. An improvement in soil resistance and in the brittleness index of fibre-reinforced clay was characterised. The proposed solution, technically feasible, enabled an optimization of the thickness of the mineral barrier.
Numerical Simulations of Canyon Topography Effects on Long-Span Bridge with High Piers under Incident SH Seismic Waves
Authors: Zhou Guo Liang , Li Xiao Jun , Meng Qing Li
Published: October 2011

To evaluate the influences of the canyon topography on large structures, based on a rigid frame bridge across a 137-meter-deep and 600-meter-wide canyon, the seismic response of the canyon topography is analyzed under seismic SH waves with the assumptions of vertical incidence and oblique incidence to obtain the surface ground motions, which are used as the excitations for the bridge. It indicates that canyon topography has significant and complex influences on the surface ground motions. The peak ground accelerations vary greatly from the bottom of the canyon to the upper corners. And the ground surface has been characterized by larger relative displacements in the case of oblique incidence. Compared with the uniform seismic excitations, it’s hard to find out any regularity on structural seismic responses considering the canyon topography effects. The canyon topography can enlarge or minish the structural responses in terms of the different structure members, and it should be a carefully considered factor in structural seismic analysis and design.
Self-Diffusion in Nano Zinc Sulphide
Authors: Ragam M. , Sankar N. , Ramachandran K.
Published: October 2011

Self-diffusion, both cationic and anionic diffusion, in ZnS nanoparticles is studied here following reaction coordinate theory. The jump frequencies, at various temperatures are computed. The isotope effect reveals the self-diffusion in nano ZnS is mainly through interstitial migration.
Optical Studies of Physically Deposited Nano-Ag2Te Thin Films
Authors: Pandiaraman M. , Soundararajan N. , Ganesan R.
Published: October 2011

Silver telluride (Ag2Te), I-VI semiconductor compound with potential applications in various advanced fields. Ag2Te nano films of thickness between 16 nm and 145 nm prepared by thermal evaporation technique at high vacuum better than 2x105 mbar. These films are found to exhibit polycrystalline nature with monoclinic structure from their XRD studies. The average particle size of these films are found to be around 24 nm using the Debye-Scherrer’s formula From AFM measurements, the average particle size is around 24 nm. The emission spectra of these films were recorded and analysed to determine its optical band gap. Optical band gap of Ag2Te varies from 1.6 eV to 1.8 eV with respect to their corresponding thicknesses of films.
Correlation between Structural Properties and In Vivo Biocompatibility of Alumina/Zirconia Bioceramics
Authors: Cavalu Simona , Simon Viorica , Ratiu Cristian , Oswald I. , Gabor R. , Ponta O. , Akin Ipek , Göller G.
Published: October 2011

The aim of our study is the characterization and comparison of structural properties of two novel alumina/zirconia ceramics prepared by Spark Plasma Sintering and biocompatibility evaluation by using an animal model (Wistar rats). SEM, XRD and FTIR spectroscopic results are reported for structural characteristics. In vivo tests demonstrated the biocompatibility and osseointegration of the composites by complementary SEM and histological analysis of the defects in rat femur respectively the connective tissue.
In Vitro Studies of Antibacterial Activity of Bioglasses Releasing Ag+
Authors: Ciołek Lidia , Karaś Joanna , Olszyna Andrzej Roman , Zaczyńska Ewa , Czarny Anna , Żywicka Bogusława , Szamałek Krzysztof
Published: October 2011

The research of obtained bioglasses in the form of silver-containing powders were presented in this paper. The research conducted in order to determine antimicrobial activity under in vitro conditions of bioglasses. The results confirmed that these bioglasses Z-5, Z-8 and B-I inhibit the growth of most micro-organisms during the tested period and could be used in surgical treatment of the most advanced parodontium illnesses.
Electrical Polarization Depresses Low Temperature Degradation and Promotes Bioactivity of Chemically Treated Yttria-Stabilized Zirconia
Authors: Nakamura Miho , Horiuchi Naohiro , Nagai Akiko , Yamashita Kimihiro
Published: October 2011

Because of its excellent mechanical properties, yttria-stabilized zirconia is currently used as an orthopedic and dental material. In this study, we have improved the bioactivity of yttria-stabilized zirconia by a combination of electrical polarization and chemical treatment. The phase transformation from tetragonal to monoclinic ZrO2 after alkaline treatment was inhibited on positively-charged yttria-stabilized zirconia surfaces compared with negatively charged and conventional surfaces. During polarization, some oxide ions move from the positively-charged surface to the negatively charged surface, leading to an increase in oxygen vacancies on the positive surface and hence greater formation of Zr-OH when this surface was exposed to alkaline solution. This then reduced the water adsorption at this surface and consequently reduced the rate of cleavage of Zr-O-Zr bonds. The bioactivity was assessed by immersing the samples in simulated body fluid and evaluating the growth of apatite on the surfaces. The combination of polarization and alkaline treatment increased the bioactivity in vitro.
Characterization of Bio-Absorbable and Biomimetic Apatite/Collagen Composite Powders Derived from Fish Bone and Skin by the Dissolution-Precipitation Method
Authors: Akazawa Toshiyuki , Murata Masaru , Ito M. , Iida Shunji , Shigyo Tatsuhiro , Nomura Takafumi , Inano Hiroyuki , Yamagishi Tohru , Itabashi Kohji , Nakamura Katsuo
Published: October 2011

Bio-absorbable and biomimetic composites (HA-C) of hydroxyapatite (HAp) and collagen were designed utilizing salmon bone and skin at 298K and pH 7.5-7.9 by a dissolution-precipitation method. The HA-C powders were consistuted by Ca2+-deficient HAp containing small amounts of Na+ and Mg2+ ions and I type-collagen. Microstructure and surface characteristics of the HA-C powders gradually changed depending on the composition ratio of HAp to collagen (H/C). The HA-C powder of H/C=3.5 had frock like-agglomerated particles consisted of nano-crystals, micro-pore, and meso-pore so that it exhibited high specific surface area (75m2¥g-1) and large total pore volume (0.543 cm3¥g-1). From adsorption isotherms of water vapor at 298K for the HA-C powders, hysteresis - curves of the amounts of water vapor adsorbed were obtained in the adsorption-desorption processes. The amounts of water vapor adsorbed for the H/C=3.5 powder were the highest values under the relative partial pressures of 0.73-0.93. At 2 weeks after implantation of the HA-C powders into the subcutaneous tissue of the back region in rats, collagen was completely bio-absorbed and body fluid permeated into large agglomerated particles, although bio-absorption by multi-giant cell- infiltration was recognized around the surface layers of HAp particles.
Synthesis of Silver Incorporated Hydroxyapatite under Magnetic Field
Authors: Rautray Tapash R. , Kim Kyo Han
Published: October 2011

Cathodic deposition of nanocrystalline hydroxyapatite coatings on titanium surface was carried out under different magnetic field conditions. The electrolyte was prepared to maintain physiological pH and was agitated using a magnetic stirrer throughout the time of electrolysis. Silver was incorporated in the current coating because of its antibactericidal and cytotoxic nature. It was found that the silver concentration in HA coated titanium without magnetic field was higher than the coating formed under magnetic fields. This may be attributed to the diamagnetic nature of silver in different magnetic field conditions.
Standardized Study of Carbonate Apatite as Bone Substitute in Rabbit’s Tibia
Authors: Cezar I. , Kammer G. , Alves A. , Calasans-Maia J. , Gress M.A. , Rossi Antonella M. , Granjeiro J.M. , Calasans-Maia M.
Published: October 2011

The objective of this study was to investigate the bone repair of carbonate apatite (cHA) in comparison to hydroxyapatite (HA, control group) on osseous repair of rabbit’s tibia. Spheres (400-500 µm) of both materials were synthesized under 37°C (cHA) and 90°C (HA) and were not sinterized. Ethics Commission on Teaching and Research in Animals approved this project (CEPA/NAL 208/10). Six White New Zealand rabbits were submitted to general anesthesia and one perforation (2mm) was made in each tibia for implantation of cHA (left tibia) and HA spheres (right tibia). After 4 weeks all animals were killed and one fragment of each tibia with the biomaterial was collected with a total of 6 bone blocks for each group. Five bone blocks of each group were demineralized and 5-µm thick semi-serial sections were stain with Hematoxillin and Eosin and Trichromic of Masson for histological analysis and two fragments were collected and embedded in a methacrylate-based resin and cut into slices with ~30 µm and were analyzed by light microscopy (bright field and polarized microscopy). Both groups didn’t show the spheres after 4 weeks, new-formed bone was observed from the periphery toward to the center of the surgical defect, which was even filled with connective tissue. Both materials are biocompatible, promote osteoconduction and showed to be resorbable.
In Vivo and In Vitro Biocompatibility Study of Nanostructured Carbonate-Apatite
Authors: Barros E. , Alvarenga J. , Alves Gutemberg , Canabarro B. , Fernandes G.V.O. , Rossi Antonella M. , Granjeiro J.M. , Calasans-Maia M.
Published: October 2011

The objective of this study was to investigate the in vitro and in vivo biological responses to carbonate apatite (cHA) in comparison to hydroxyapatite (HA). Spheres (400<ø>500 μm) of both materials were synthesized under 5°C (cHA) and 90°C (HA) and not sintered. The in vitro cytocompatibility was determined by the XTT assay, according to ISO 10993-5:2009, after exposure of MC3T3-E1 cells to the materials extracts. Ethics Commission on Teaching and Research in Animals approved this project (CEPA/NAL 193/10) and, subsequently, the biomaterials were grafted in the subcutaneous tissues of mice (n=15). After 1 and 3 weeks, five animals of each group were killed for samples removal containing biomaterials and surrounding tissues for histological examination. Semi-serial (5-μm thick) sections were cut and stained with Hematoxylin and Eosin (HE) and the presence of inflammatory infiltrates and biomaterials resorption were evaluated. The experimental group of 3 weeks didn’t show the presence of spheres of both biomaterials and few spheres were observed after 1 week. Histological analysis showed the granulation tissue around the biomaterials with the presence of multinucleated giant cells. After 3 weeks it was observed the presence of fibrous tissue around biomaterials and few inflammatory cells. No signals of tissue necrosis were observed in both groups in all experimental studied periods. Nanostructured carbonate apatite spheres are cytocompatible, biocompatible and present initial biosorption on the subcutaneous comparable to stoichiometric HA, indicating its suitability for further studies on regenerative medicine.
Study of Bone Repair in Rat Dental Socket after Implantation of Porous Granules of Beta-Tricalcium Phosphate (β-TCP) and Magnesium-Substituted Beta-Tricalcium Phosphate (β-TCMP)
Authors: Yassuda-Mattos Debora Helena , de Freitas Costa Neusa Motta , Tavares Débora dos Santos , Fernandes G.V.O. , Alves A. , Granjeiro José Mauro , de Almeida Soares Gloria Dulce
Published: October 2011

Porous granules were obtained through a route using a mixture of calcium phosphate powder with sodium alginate solution. The sintered β-TCP and β-TCMP granules with diameters ranging from 250 µm to 500 µm were implanted into dental alveoli of 30 rats (Rattus norvegicus). The animals were divided in three groups: group I (control, no treatment), group II (β-TCP) and group III (β-TCMP); the sacrifices occurred at 7 and 21 days (n=5/group/period). Histological and histomorphometric analysis were performed to observe and measure connective tissue, bone neoformation and biomaterial areas. Most animals showed acute inflammatory response with many neutrophil granulocytes and foreign body giant multinucleated cells associated to both biomaterials, at 7 and 21 days. The utilization of sodium alginate as additive in the porous granules might explain these results. Fourier-transformed infrared spectroscopy (FTIR) pointed out residue in the granules surface that could exacerbate the inflammatory response. Additional studies are in course to confirm such hypothesis.
Biochemical Studies of the Potential Anti-Tumor Activity of Novel Chelate-Setting Apatite Cements
Authors: Konishi Hidenori , Honda Michiyo , Aizawa Mamoru , Kanzawa Nobuyuki
Published: October 2011

The anti-tumor activity of hydroxyapatite (HAp) cements, which had been developed using a novel setting mechanism termed chelate bonding, against the human osteosarcoma cell line (HOS) and rat bone marrow stromal cells (BMSC) was examined. We aimed to understand the mechanism of the anti-tumor activity of the cement, thereby facilitating improvement of its biological activity. HAp powders were surface-modified with three different concentrations of inositol hexaphosphate (IP6), which were then used to fabricate three different IP6-HAp cements. The amount of IP6 that was bound to the HAp powder, and the amount that was released from the HAp cement, was measured for each sample. Approximately 1/200 to 1/1600 of the bound IP6 was released into the culture medium by day 4. Surface-modification of HAp with high concentration of IP6 inhibits the proliferation of both HOS cells and BMSCs, and appears to induce their apoptotic cell death. HOS cells were slightly more sensitive to IP6 than BMSCs. Thus, novel, chelate-bonded HAp cements are a candidate bone substitution material that exhibit anti-tumor activity.
Hydroxyapatite Ceramics Including Bone Minerals Promote Differentiation of Osteoblasts Derived from Rat Bone Marrow Cells
Authors: Aizawa Mamoru , Miki Takuya , Yasutomi Yumiko , Honda Michiyo , Yoshimura Hideyuki
Published: October 2011

Biological apatite presented in bone and teeth of mammals contains various minerals; thus, it has lots of defects with nano-scale sizes in the crystal structure. We fabricated hydroxyapatite ceramics including bone minerals (bone HAp ceramics) as model materials to clarify the relationship between nano-defect structure and bioactivity of biological apatite. The X-ray diffraction (XRD) results indicated that crystalline phase of pure and bone HAp ceramics were of HAp single phase. Chemical compositions of pure and bone HAp did not change before and after firing at 1000 °C for 5 h. Microstructure observed by high-resolution transmission electron microscope (HR-TEM) indicated that bone HAp ceramics contained more defects and strains compared to pure HAp ceramics. Osteoblasts derived from rat bone marrow cells (RBMC) were seeded on both pure and bone HAp ceramics. The level of differentiation into osteoblasts was examined by determining the content of alkaline phosphatase (ALP) for initial/middle stage and osteocalcin (OC) for late stage. The ALP activity normalized for DNA content of osteoblasts cultured on the bone HAp ceramics was higher than that of pure HAp ceramics. The OC amount normalized for DNA content of bone HAp ceramics was the almost same as that of pure HAp ceramics. These results demonstrate that the bone HAp ceramics may promote the differentiation into osteoblast.
Fabrication of Janus Microfiber in Microfluidic System
Authors: Jeong Heon Ho , Lee Sang Ho , Lee Chang Soo
Published: October 2011

This study presents a novel synthetic approach for the preparation of cell attachable microfibers in microfluidic system. The synthesis is performed by multiphase laminar flows with spontaneous formation of carbon dioxide bubbles resulting asymmetrically porous PU microfiber. The fabricated Janus microfiber provides two distinctive properties: one is porous region to promote the cellular adhesion and the other is nonporous region rendering mechanical strength of the scaffold. The Janus microfibers show dramatic improvement of cell adhesion, proliferation, and viability over a culture period. The Janus microfiber can be used for not only alternative 2D cell culture plate but also as novel 3D scaffold for tissue engineering wihtout any need of elegant surface modification for enhancing cell adhesions.
Investigations on Degradable and Figuline Calcium Alkaline Phosphate Cements with Multimodal Particle Size Distribution
Authors: Dombrowski F. , Hoffmann R. , Ploska Ute , Marx Heidi , Berger Georg
Published: October 2011

The paper presented here deals with rheological and hardening properties during the setting reaction, and density and compressive strength after the final setting of a figuline composite consisting of Ca2KNa(PO4)2 and 2wt% medium gel strength gelatin. Compared to the composite with monomodal particle size distribution (d50=7.18µm; span=3.9) and its properties during and after setting reaction, the goal of this work is to increase the resulting product compressive strength by mixing different particle sizes in order to obtain bi- and trimodal distributions. For the bimodal powder mixtures the ratio in diameter (dcourse/dsmall) was chosen with 7/1 and volume ratio dcourse/dsmall was 70/30%. For the trimodal powder mixtures the ratio in diameter (dcourse/dmedium/dsmall) was chosen with 70/7/1 and volume ratio dcourse/dmedium/dsmall was set to 44/28/28%.After establishing an adequate crushing and sieving process the tap density and powder density of each fraction was determined. Subsequently, the different particle sizes were mixed and the densities and the Hausner ratio were determined again. The mixtures show an increase in both densities especially the tap density increased significantly. Rheological investigations show that the graphs of storage and loss moduli of the multimodal powder mixtures respectively are similar. The characteristic setting times show a slight decrease compared with the monomodal composite but not significantly different data. When comparing the resulting compressive strength of cylindrical samples, which were stored direct after reaching the initial setting time under physiological conditions, the studies illustrated in all cases for the multimodal mixtures a significant increase in compressive strength and a higher density.
Fabrication of Chelate-Setting Cement Using Silicon-Substituted Hydroxyapatite and its Property
Authors: Nakashima Y. , Honda Michiyo , Konishi Toshiisa , Mizumoto Minori , Aizawa Mamoru
Published: October 2011

We have developed novel hydroxyapatite (HAp) cement, “chelate-setting HAp cement” on the basis of chelate bonding of inositol hexaphosphate (IP6). In order to create the cement with enhanced bioactivity, we used a silicon-substituted hydroxyapatite (Si-HAp) as a starting material instead of pure HAp powder. The Si-HAp powders were prepared via an aqueous precipitation reaction and surface-modified with IP6 (IP6-Si-HAp). The Si-HAp were synthesized with desired Si contents (0, 0.4, 0.8, 1.6, and 2.4 mass%). Regardless of the amount of Si, the XRD patterns and FT-IR spectra of the powders were similar to each other. Additionally, chemical composition of Si-HAp powders were the almost same as the nominal one. The substitution of Si resulted in a decrease in the a-axis and increase in the c-axis of unit cell of HAp. While, the compressive strength of IP6-Si-HAp cements was higher than that of Si-HAp cements. These results suggest that surface-modification of any powders with IP6 is effective for enhancement of mechanical property. Comparison of mechanical property between HAp and Si-HAp cement specimens revealed that the substitution of lower levels of Si into0 HAp lattice did not greatly influence compressive strength. However, the substitution of high dose of Si (over 2.4 mass%) reduced the compressive strength. Therefore, to fabricate the chelate-setting cements with enhanced bioactivity, it is necessary to control the amount of Si.
PH Evolution and Cytotoxicity of [Alpha]-Tricalcium Phosphate Cement with Three Different Additives
Authors: Cardoso H.A.I. , Motisuke M. , Rodas A.C.D. , Higa O.Z. , Zavaglia Cecília A.C.
Published: October 2011

An application of calcium phosphates is as bone cements, among which the system based on alpha-tricalcium phosphate (α-TCP) exhibits excellent properties. The aim of this study is to analyze pH evolution and cytotoxicity of α-TCP cement with three different additives. Changes on the pH were measured at intervals of 12h during seven days. But initial measurements were executed at each 15 minutes. Indirect cytotoxicity test was performed according to ISO (10993-5, 1992) employing CHO-k1 cells and RPMI 1640 as culture medium. It was used a colorimetric method which uses the tetrazolium compound. The additives used on the liquid phase were disodium hydrogen phosphate (Na2HPO4) and/or citric acid (C6H8O7) and/or tannic acid (C76H52O46). The results indicate that the cement without additives does not have requirements to be applied like bone cement, while the other cements composition exhibit different responses in the pH and the cytotoxicity test. In conclusion, due to the presence of additives it was possible to control pH evolution during setting and cytotoxic response. However, further investigation is necessary in order to determine the influence of these additives, mainly tannic acid, on the in vivo behavior of these bone cements.
Fast Deposition of Nanocrystalline Hydroxyapatite into Additive Manufactured Titanium Porous Structures
Authors: Bracci Barbara , Panzavolta Silvia , Bigi Adriana , Prosperi S. , Bucciotti F.
Published: October 2011

This paper reports the results of a study aimed to deposit a biomimetic apatitic coating on the porous surface of Ti alloy acetabular cups, produced with AM techniques. To this purpose, we utilized a slight supersaturated Ca/P solution at physiological values of pH and temperature. The results of the XRD, SEM and EDS investigation indicate the 6 h immersion in the calcifying solution are sufficient to provoke the deposition of a uniform coating of poor crystalline apatite on the surface and inside the porous structure of the substrates.
How to Enhance Osseointegration – Roughness, Hydrophilicity or Bioactive Coating
Authors: Adam Martin , Ganz Cornelia , Xu Wei Guo , Sarajian Hamit R. , Frerich Bernhard , Gerber Thomas
Published: October 2011

The apposition of bone at early stages is critical for rapid loading and therefore there is much effort in improving the implant surfaces for a rapid osseointegration. The aim of this study is to investigate the effect of roughness, hydrophilicity and coating on osseointegration. Machined (smooth), sand-blasted (rough), hydrophilic and coated implants were tested in vivo for 2, 4 and 6 weeks. The hydrophilic surfaces were obtained by atmospheric oxygen plasma treatment of machined and sand-blasted implants. The coating is obtained by a spin-spray-process using sol-gel-technique. SEM and TEM investigations revealed that the coating consists of a nanoporous silica matrix with embedded synthetic, nanocrystalline hydroxyapatite. Histological polished sections were manufactured and the bone-to-implant-contact was calculated. The difference between smooth and rough implants was marginal and not significant. There were no statistical differences between hydrophilic and control implants, whereas the BIC of the hydrophilic surfaces was lower by trend. All coated implants offered an increased bone to implant-contact. However, the BIC was decreasing at 6 weeks due to the missing of mechanical stress and a faster bone metabolism in rabbits. The coating offers a new opportunity to enhance the osseointegration and therefore an earlier implant loading.
Studies of Hydroxyapatite Thin Coating Produced by Dual RF Magnetron Sputtering for Biomedical Applications
Authors: Lopez E.O. , Borghi F.F. , Mello Alexandre , Gomes J. , Rossi Antonella M.
Published: October 2011

In this present work, we characterize HAp thin films deposited by dual magnetron sputtering device DMS on silicon (Si/HAp). The sputtering RF power was varied from 90 watts to 120 watts and deposition times from 60 to 180 minutes. The argon and oxygen pressure were fixed at 5.0 mTorr and 1.0 mTorr, respectively. Grazing incidence X-ray diffraction (GIXRD) from synchrotron radiation, infrared spectroscopy (FTIR) and atomic force microscopy (AFM) were used for the structural characterization. At lower deposition times, a crystalline phase with preferential orientation along apatite (002) and a disordered nanocrystalline phase were identified. The coating crystallinity was improved with the increase of the deposition time besides the sputtering power.
Bioactive Coating on Porous Materials with an Interconnected Pore System to Improve Osseointegration
Authors: Keuer Holger , Ganz Cornelia , Xu Wei Guo , Frerich Bernhard , Gerber Thomas
Published: October 2011

The purpose of the present study was to evaluate the role of bioactive surface coating and geometric design of orthopedic implants. In return, a 3-dimensional model with a interconnected macroscopic por system (IMPS) was designed. The model was created by using the place holder method with titanium powder and ammonium bicarbonate. After sintering one group of the IMPS-model was penetrated with plasma to create hydophilic surface. The second group was coated with the biomaterial NanoBone and the third was an untreated controll group. All three groups were used for an experimental pilot study in rabbit femora to determine the osseointegration process after 4 and 12 weeks. The biomaterial coated group points an approximately 10 % higher bone to implant contact compared with the two other groups.
Nanomechanical Properties of Bioactive Ti Surfaces Obtained by NaOH-Based Anodic Oxidation and Alkali Treatment
Authors: Szesz Eduardo Mioduski , de Souza G.B. , Santos Emanuel , Kuromoto Neide K.
Published: October 2011

Titanium has been used in the production of dental implants and orthopedic prostheses due to the low tendency to corrosion and good biocompatibility. Meanwhile, the surface of titanium is not bioactive. Several surface treatments have been developed to make the surface of such metals bioactive. The aim of this work was to evaluate two of these modification processes in commercially pure titanium grade 2, both of them using NaOH solutions: the anodic oxidation and the alkali treatment. The surface morphology was evaluated by SEM/EDS, the crystal structure by XRD, and the mechanical properties and scratch resistance by instrumented indentation. The anodic oxidation (AO) was carried out using NaOH electrolyte 0.1 mol/L and constant current density of 150 mA/cm² for one minute. The alkaline treatment (AT) was performed by soaking the Ti sample in NaOH 5 mol/L solution at 60 °C for 24 hours; after this, the sample was heat treated at 600 °C for one hour in atmospheric air. The AO produced a TiO2 layer on Ti, whereas a thin sodium titanate layer was obtained by AT. Each surface modification resulted in a specific morphology, but both of them presented the increase in roughness as a common characteristic. The alkali treated Ti surfaces showed the lowest elastic modulus and hardness values. The largest increase in hardness between the treated surfaces was obtained for Ti after anodic oxidation. Scratch test indicates that the TiO2 film from AO has higher strength to tangential loading than the Ti substrate. In addition, for the Ti submitted to AT, the scratch test indicates that the modified surface layer has a poor adhesion with the substrate. Based on these results it is possible to conclude that, using NaOH solutions, Ti surfaces treated by anodic oxidation present improved mechanical properties than the alkali-treated ones.
Fabrication of Organic/Inorganic Hybrids by Infiltration of Commercially-Available PLGA into Porous Hydroxyapatite Ceramics and its Material Properties
Authors: Osada Naoki , Shigemitsu Yusuke , Makita Masashi , Oribe Kazuya , Aizawa Mamoru
Published: October 2011

Hybrids of hydroxyapatite (HAp) and poly(L-lactic co glycolic) (PLGA) have been fabricated, which can be expected to be a novel ﬁller for bone grafting. The porous HAp ceramics with bimodal pore structure have been fabricated from apatite fibers synthesized by homogeneous precipitation method. Then, HAp/PLGA hybrids have been fabricated by introducing PLGA having high molecular-weight into the open pores of the porous HAp ceramics. Total porosities of the porous HAp ceramics slightly decreased from 71.5% down to 67.4% after infiltrating PLGA into the porous HAp ceramics. The bending strength of the HAp/PLGA hybrids was ~ 8.3 MPa. The value attained about 2 times that of the porous HAp ceramics.
Silicate and Calcium Ions Releasing Biomaterials for Bone Reconstruction
Authors: Nakamura Jin , Obata Akiko , Jones Julian R. , Kasuga Toshihiro
Published: October 2011

Siloxane-containing vaterite (SiV) / poly (lactic acid) hybrid (SiPVH) beads with the releasability of silicate and calcium ions were prepared with an electrospraying method. According to the increase in the silicon content of the SiV, the amount of silicate ion released from the resulting beads also increased. When the beads were soaked in a cell culture medium, proteins derived from fetal bovine serum were adsorbed on their surfaces. Cell adhesion tests were also performed on the beads with using mouse osteoblast-like cell line (MC3T3-E1) in vitro. After 5 days of culturing, the cells adhered and spread well to cover the surface of the beads. In the localized area, agglomerated cells were observed to combine with cauliflower-shaped calcium phosphate deposits.
Preparation and Characterization of Polylactide-co-glycolide/Carbonate Apatite (PLGA/CHA) Composite Scaffolds
Authors: Stone Heather Elizabeth , Lu Helen , LeGeros Racquel Z.
Published: October 2011

Both natural and synthetic materials have been utilized to provide three dimensional scaffold environments ideal for bone repair. The biomechanical and biocompatibility characteristics of these scaffolds play a vital role in successful tissue engineering constructs. Polymer/carbonate apatite (CHA) composites have shown to improve cell adhesion and proliferation on the scaffold as well as increase elastic modulus, toughness and strength. The aim of this study is to prepare CHA- polylactic-co-glycolide (PLGA) composites in the form of microsphere, scaffold and disc and evaluate their physico-chemical properties, mechanical properties and in vitro bioactivity. 3-D porous cylindrical composite scaffolds were prepared using PLGA/CHA composites with varying PLGA/CHA ratios (30:70 and 50:50). The CHA was prepared by hydrolysis method and characterized using x-ray diffraction (XRD) and Fourier Transform Infrared spectroscopy (FTIR). The physico-chemical and mechanical properties of the composite scaffolds were evaluated using scanning electron microscopy (SEM), micro-computed tomography (μCT), XRD, FTIR, and thermogravimetry (TGA). Flexural strength was determined using Instron. In vitro bioactivity was determined by the formation of apatite on composite disc surfaces after immersion in simulated body fluid (SBF). SEM and μCT analyses showed high porosity and interconnectivity between microspheres in the composite scaffolds. In vitro bioactivity was observed by the development of an apatite layer on the surfaces of the composite scaffolds after immersion in simulated body fluid. The mechanical strength of the scaffolds was to be dependent on the PLGA-CHA ratio. The elastic modulus, toughness and strength values obtained for the composites were similar to those of reported bone substituted materials. Results from this study provided information on the fabrication of PLGA-CHA scaffolds and their properties that may be useful for their potential application in bone repair and as scaffolds in tissue engineering for bone regeneration.
Influence of Nano-Hydroxyapatite Addition to Calcium Hydroxide Cement on its Properties
Authors: Zamanian Ali , Yasaei Mana , Moztarzadeh F. , Hesaraki Saeed , Hafezi Masoud
Published: October 2011

Calcium hydroxide cement used in dentistry has advantages of proper alkaline pH, releasing calcium ions and promoting tissue regeneration. However, it also has some drawbacks such as high solubility and low strength. In this study, the properties of nano-hydroxyapatite (nHA) added calcium hydroxide cement was investigated for overcoming these drawbacks. Stoichiometric nHA powder was synthesized using orthophosphoric acid and calcium hydroxide. 5, 10 and 15 percent (in w/w) of synthesized nHA powder was added to commercial calcium hydroxide cement and the obtained nanocomposite was characterized by setting time, compressive strength, pH, Ca dissolution, antibacterial tests and SEM. Nanometric size and purity of synthesized apatite was confirmed by XRD and TEM. Setting time increased by increasing the content of nHA. SEM micrographs showed less microporosity for sample with 5% nHA. Adding 5% nHA to calcium hydroxide cement increased compressive strength to 60%, while further additions had an adverse effect. Adding nHA slightly decreased pH and increased Ca dissolution. The antibacterial test revealed that inhibition zone was about 2-2.5 mm for calcium hydroxide cement and sample with 5% nHA and less than 1 mm for other samples. Finally, nanocomposite with 5% nHA exhibited adequate properties to overcome the drawbacks of calcium hydroxide cements.
The Effect of Five Polishing Materials on the Surface Roughness of Acrylic and Composite Denture Resins
Authors: Ozyegin L.S. , Yesilbek B. , Bayrak O. , Oktar F.N.
Published: October 2011

Rough surfaces of denture prosthesis promote adhesion of microorganisms and plaque formation. In dentistry ferric oxide, tin oxide, chrome oxide and pumice are the most commonly used materials for polishing of resins and other materials. Clinoptilolite that is in zeolitic structure resembles to pumice due to alumina silicate formations in its constitution. Surface roughness was evaluated by means of a surface roughness analyzing instrument, Perthometer There were 10 specimens for each acrylic resin and bis-acryl composite resin material and polishing method combination. Conventional lathe polishing with polishing paste served as surface roughness was determined with a profilometer and SEM microscope. ANOVA was applied to the all measurements and was statistically significant (p<0.001). The p-values were calculated using paired t-tests. The materials in order that are most successful at polishing PMMA surface are; clinoptilolite Ra 0,5 > Fe2O3 Ra 0,6 > Cr2O3 Ra 0,8> pumice Ra 1,2 > SnO2 Ra 1,6. the surface roughness values for Bis-acryl Composite are as follows: clinoptilolite Ra 0,6 > Fe2O3 0,8 Ra > Cr2O3 Ra 0,9 > pumice Ra 1,4 > SnO2 Ra 1,9. The most successful material for PMMA and Composite resin were clinoptilolite followed by; clinoptilolite, Fe2O3, Cr2O3, pumice, and SnO2 in order. The same results were confirmed with the scanning electron microscopic images. Within the light of the present study Clinoptilolite can be an alternative to pumice for polishing of PMMA.
Preparation of Silver-Containing Hydroxyapatite Powder by Ultrasonic Spray-Pyrolysis Technique and its Antibacterial Property
Authors: Kawanobe Yusuke , Honda Michiyo , Konishi Toshiisa , Mizumoto Minori , Habuto Yuri , Kanzawa Nobuyuki , Zhuang Zhi , Aizawa Mamoru
Published: October 2011

We prepared silver-containing hydroxyapatite (Ag-HAp) powders by an ultrasonic spray-pyrolysis (USSP) technique and evaluated their antibacterial activity.　　Ag-HAp powders with Ag contents of 0, 1, 2, 5, and 20 mol% as nominal composition were prepared by the above USSP technique. The droplets of starting solutions were dried at 300 °C and then pyrolyzed at 850 °C to prepare the Ag-HAp powders. Ag-HAp powders showed a HAp single phase and were composed of spherical particles with a diameter of 0.5 - 3.0 μm. To evaluate the antibacterial activity of resulting powders, colony count method was performed using Staphylococcus aureus. Ag-HAp powders with the contents of Ag more than 5 mol% showed good antibacterial activity.
Investigation of the Phase Separation Occurring during the Injection of β-Tricalcium Phosphate – Water – Glass Beads Pastes
Authors: Tadier S. , Galea Laëtitia , Gruenenfelder S. , Bohner Marc
Published: October 2011

Tests were performed to assess the parameters influencing the injectability of cement pastes loaded with large particles, such as porogens or drug-delivery agents. The use of non-setting model pastes permitted to demonstrate that two phase separation mechanisms occurred simultaneously, i.e. the separation between liquid and powder, known as filter-pressing phenomenon, and the separation between larger and smaller particles.
Poly(lactic-co-glycolic)/Nanostructured Merwinite Porous Composites for Bone Tissue Engineering. I. Preparation and Morphology
Authors: Hafezi-Ardakani Masoud , Kavian Faranak , Moztarzadeh Fatollah , Eslaminejad Mohamadreza Baghaban , Zamanian Ali , Bagheri Fatemeh
Published: October 2011

A novel merwinite/ Poly(lactic-co-glycolic) nanocomposite was synthesized by a solvent casting/salt leaching technique with varying merwinite contents from 10 to 30% (w/w). Poly(lactic-co-glycolic) /merwinite foams with a co-continuous structure of interconnected pores were formed. The microstructure of the pores and the walls was controlled by varying the merwinite content. The pore structure becomes more and more irregular with increasing merwinite content. Pore sizes ranging from several microns to a few hundred microns were obtained. The degradation assessment of the scaffolds is performed in phosphate-buffered saline (PBS) solution at 37°C. Weight loss during storage at 37°C in PBS (pH 7.4) was determined for the scaffolds. Weight loss increased from pure to high content during incubation time. The prepared merwinite/ (Polylactic-co-glycolic) nanocomposite with uniform microstructure may be used in bone tissue engineering applications.
TEM Observation of Biomolecules on/in Mesoporous SBA-15
Authors: Yokogawa Yoshiyuki , Saito Akira , Ogawa Naoki , Nakamura Atsutomo , Kishida Ippei
Published: October 2011

The encapsulation and immobilization of biomolecules on/in mesoporous silica materials (MPS) have been studied by using transmission electron microscopy (TEM). The mixture of tetraethyl orthosilicate (TEOS) and the triblock copolymer as a template was stirred, hydrothermally treated to form the mesoporous SBA-15 structure, and heat-treated at 550 °C. SEM observation indicated that long and narrow particles were linked together in the long axis direction to form secondary particles of SBA-15. UV-spectrometry was performed to determine the amount of bovine serum albumin (BSA), cytochrome C, myoglobin or -lactoglobulin encapsulated on/in SBA-15. The time profiles for adsorption of proteins can be well described by intraparticle diffusion model. The TEM observations of proteins on/in mesoporous SBA-15 revealed that proteins were embedded on/in mesoporous SBA-15 and the protein behaviors given by TEM observations may correspond to the intraparticle diffusion model.
Internal Diffusion of Biocompatible Polymer-Coated Inorganic Nanoparticles in Mice
Authors: Abe Shigeaki , Sakaki Akiko , Narushima Takashi , Uchida Yoshiki , Akasaka Tsukasa , Uo Motohiro , Yonezawa Tetsu , Watari Fumio
Published: October 2011

In this study, we succeeded in preparation and characterization of two types of biocompatible polymer-coated inorganic nanoparticles (cupper and silicone oxide). As a biocompatible polymer, gelatin and poly(lactic acid) were used. For determination of their biodistribution, the obtained particles were administered to mice through the tail vein. After administration, the particles in some organs were determined with energy-dispersed X-ray spectrometer. The cupper nanoparticles were observed in the lung and kidney, while the silica particles were in the lung, liver and spleen. The distribution behaviors were quite different from non-polymer coated nanoparticles
Preparation of Porous Wollastonite Microspheres
Authors: Maeda Hirotaka , Okuyama Tatsuya , Ishida Emile Hideki , Kasuga Toshihiro
Published: October 2011

Novel porous wollastonite microspheres for releasing silicate and calcium ions were prepared by electrospraying using a hydrolyzed alkoxide. Wollastonite formed in the microspheres by heating the electrosprayed precursor microspheres at 850 °C for 2 h. Numerous pores of 100-300 nm in diameter were newly formed at the surface of the microspheres. The size of porous wollastonite microspheres was determined to be 1-5 µm in diameter.
The Impact of Sintering Temperature on the Bioactive Glass-Dental Porcelain Composite Material
Authors: Manda M. , Goudouri Ourania Menti , Papadopoulou Lambrini , Kantiranis Nikolaos , Zorba T. , Chrissafis K. , Paraskevopoulos Konstantinos M. , Koidis Petros
Published: October 2011

End temperature of the firing cycle, during processing of dental ceramics, directs the interaction of both sintering and crystallization pathways, tailoring physicochemical properties and bioactivity. Thus, the purpose of the present study was to investigate the influence of end temperature over the structural properties and composition, along with the bioactive behavior of dental porcelain, modified by bioactive glass. Sol-gel derived specimens of bioactive glass (58S)- commercial dental porcelain composites synthesized (BP) and underwent firing cycles at the crystallization temperature (Tc=1040oC) and the temperature just below the melting range (Tm=1080oC), as the composite material. The recommended temperature for the commercial porcelain (Ta=930oC) was examined, too. All specimens were characterized using X-ray diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM). The assessment of bioactivity was performed in vitro, via the detection of apatite layer development. The well-defined particles, observed by SEM, at 930oC, developed contact formation during the stage of neck growth at 1040oC and 1080oC, indicating the initiation of sintering process. Increasing temperature, the complex porei network became smoother, while spherical and closed porei were evident. FTIR revealed the predominance of wollastonite at the increased temperatures, along with the appearance of cristobalite, while XRD confirmed the results. Finally, the in vitro tests evidenced the bioactivity of the specimens independently of the final temperature, though the increased temperature caused delayed apatite layer formation on their surface. The, microstructural and chemical evolution of the studied composite is temperature-dependent. Increased temperature favored the sintering process initiation, along with the surface crystallization, which delays bioactivity.