bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of Hydroxyapatite Film by Powder Jet Deposition after Artificial Aging
Authors: Akatsuka Ryo , Matsumura Ken , Noji Miyoko , Nishikawa Chihiro , Sato Kei , Hagiwara Takayuki , Anada Takahisa , Suzuki Osamu , Kuriyagawa Tunemoto , Sasaki Keiichi
Published: November 2012

This study aimed to create a thick hydroxyapatite (HAp) film on the surface of a human tooth by using a newly developed powder jet deposition (PJD) device for dental handpieces, and sought to examine the microstructural and mechanical properties of the resulting HAp film. The film was evaluated on three-dimensional view, surface roughness, Vickers hardness, and bonding strength before and after artificial aging through thermal cycling (555°C) for 500 cycles (30 sec for each cycle, 20 sec of dwell time).The HAp particles in the deposited film were densely packed, and the HAp films three-dimensional microstructure and its rough surface were maintained after thermal cycling. There was no significant difference in either the HAp films Vickers hardness or the bonding strength between the film and the enamel substrate before and after thermal cycling. The HAp films created in this study demonstrated excellent microstructural and mechanical properties even after the application of thermal stress. We demonstrated the possibility of using a new type of powder jet deposition (PJD) method we developed to form a new type of interface between the tooth and biomaterials. Consequently, we propose the use of this method in new dental treatments.
Formation of Oriented Hydroxyapatite Crystals in a Hydrogel
Authors: Yokoi Taishi , Kim Ill Yong , Masakazu Kawashita , Ohtsuki Chikara
Published: November 2012

Calcium phosphatepolymer composites have been produced for bone-repairing. We have focused development of composites by a crystal growth technique in a hydrogel matrix, that is regarded as gel-mediated processing. Under the gel-mediated condition, reaction temperature is one of the major parameter to determine microstructure of the precipitated crystals. In the present study, we investigated effects of the reaction temperature on formation of calcium phosphates through gel-mediated processing where double diffusion technique was applied. Crystalline phases of calcium phosphate formed in the hydrogel were varied from octacalcium phosphate (OCP) to hydroxyapatite (HAp) with increasing the reaction temperature. OCP crystals formed at 4 and 40 °C had granular or spherical shape, while HAp crystals formed at 80 °C had rod shape. The HAp crystals were composed of a large number of fibrous crystals. The rod-shaped HAp crystals were oriented in the direction of ion diffusion. Formation of oriented HAp crystals was generated by increase in diffusion rate of ions in the hydrogel matrix after increasing reaction temperature in gel-mediated processing.
Electrolytic Deposition of Calcium Phosphates Films on Nitinol Stents
Authors: Kondo Daisuke , Yoshioka Tomohiko , Ikoma Toshiyuki , Takamatsu Kensuke , Ohta Kunihiro , Tanaka M.
Published: November 2012

Calcium phosphates films were deposited onto pipes and stents of nitinol alloys by an electrolytic deposition (ELD) method. Monocalcium phosphate (Ca (H2PO4)2·H2O) solutions were used as the electrolyte, and electric depositions were carried out at the constant cathode current of 1.59 mA/cm2 at 65°C for 60 min. From the deposition on nitinol pipes, deposition rates were changed in 15 minutes and the precipitates were identified to be octacalcium phosphate (Ca8H2(PO4)6·5H2O) and dicalcium phosphate anhydrous (CaHPO4). The electrolytic depositions on the nitinol alloys were useful for the formation of calcium phosphates films on the complex shape of stents.
Effects of Hydrothermal Treatment on Properties of Titanium Nitride Coating for Dental Implants
Authors: Shi Xing Ling , Tsuru Kanji , Kawachi Giichiro , Kunio Ishikawa
Published: November 2012

To improve surface hardness of dental implant made of pure titanium (Ti), titanium nitride (TiN) coating was introduced. However, studies revealed that TiN only showed osseointegration similar or inferior to that of Ti. Therefore it is necessary to improve the biocompatibility of TiN for dental implant coating. In the present study, TiN coating was prepared on pure Ti substrates and hydrothermal treatment was conducted to modify its surface properties. It was found that, TiN surface was partially oxidized after treatment and calcium (Ca) was successfully combined onto its surface. Surface morphology, roughness and hardness were not affected after treatments below 140°C and wettability was obviously improved.
Autologous Bone vs. Allograft Bone in Ridge Augmentation
Authors: Ratiu Cristian , Cavalu Simona , Miclaus V.
Published: November 2012

Most of edentulous areas need reconstructive procedures of hard tissues for an ideal implant position. In this perspective, guided bone regeneration with semi-permeable membranes or onlay bone grafts harvested from intra-or extra-oral sites is indicated. Establishment of well regulated tissue banks allows surgeons use of allograft bone. This study compares two clinical cases, where a relevant horizontal deficit was present: first one reconstructed with allograft bone + titanium mesh and the other one with onlay graft + autogenous cortico-spongiosa bone particles, harvested from ramus. In both cases plasma rich in growth factors and fibrin membranes were used in order to enhance graft vascularization and osseous regeneration, as well as faster healing.
In Vivo Comparative Study of Two Injectable/Moldable Calcium Phosphate Bioceramics
Authors: Miramond Thomas , Aguado E. , Goyenvalle E. , Borget Pascal , Baroth Serge , Daculsi G.
Published: November 2012

Calcium phosphate bioceramic granules associated with hydrosoluble polymers formed putties currently more used in clinical applications as they are easy to handle (injectability, moldability). In this study, 2 kinds of materials were tested in rabbit bone defects. The first one is InOss (Biomatlante), a microporous biphasic CaP granules (BCP, HA/TCP mixture) with polysaccharidic hydrogel; and the second one is Actifuse ABX (Baxter/Apatech), pure hydroxyapatite granules containing silicate (HA-Si) with blocks copolymer hydrogel (poloxamer), . The aim of this study was to compare osteogenic properties of two kinds of CaP putties containing HA-Si versus BCP and the kinetic of resorption of their hydrogel. Data have demonstrated that both hydrogels increase the handling properties. Bone regeneration was observed in the two types of sample, however at 3 weeks, Actifuse ABX hydrogel was not totally absorbed, while InOss hydrogel was no longer observed. The second difference observed was osteoconduction. Newly formed bone over the time period studied was moreover in close contact with BCP granules than with HA-Si granules. Larger granules resorption on time was observed for BCP compared to HA-Si. Resorption of Actifuse ABX remains limited and explains the faster kinetic of absorption for InOss. This study demonstrates biocompatibility, absorbability and bone ingrowth at the expense of the two types of putty injectable/moldable bioceramic used for bone regeneration.
Cortical Bone Tissue Response of Injectable Octacalcium Phosphate-Hyaluronic Acid Complexes
Authors: Suzuki Kentaro , Anada Takahisa , Honda Yoshitomo , Kishimoto Koshi N. , Miyatake Naohisa , Hosaka Masami , Imaizumi Hideki , Itoi Eiji , Suzuki Osamu
Published: November 2012

We have previously shown that synthetic octacalcium phosphate (OCP) displays highly osteoconductive and biodegradable characteristics. However, OCP cannot be sintered without thermal decomposition due to the existence of water molecules in the structure. The acquisition of the moldability and the improvement of the handling property in this material are subjects for the clinical use. In the present study, we prepared OCP complex with hyaluronic acid (Hya) that could be used in the injectable form and further examined the bone tissue reaction to cortical bone by placing the complex directly on an 8-weeks-old ICR mouse calvaria in comparison with the placement of OCP granules only. The granule form of OCP (between 300 to 500 μm in diameter) was mixed with sodium hyaluronic acid with molecular weights 90 x 104. The complex revealed an injectable characteristic if it was utilized in a syringe. After polytetrafluoroethylen ring was mounted on mouse calvaria, the inner space of the ring was filled with the complex and left the complex as it is for 6 weeks. Histological examination using the decalcified specimens indicated that the OCP/Hya complex exhibited greater bone formation than OCP granules only group within the ring at 6 weeks. The results suggested that the OCP/Hya complex could be used as an injectable and osteoconductive bone substitute material in many clinical situations.
Assessment of the Elastic Properties of Human Femoral Bone with Artificial Hip Joint by Ultrasound Transmission
Authors: Suetoshi Ryoichi , Cretin Dorian , Ogawa Shinji , Nakano Takayoshi
Published: November 2012

Following artificial hip joint implantation, a stress inhibition, applied to bone in the surroundings of implants, causes a structural change in bone called bone loss. To evaluate the bone mechanical characteristics, it is essential to investigate the elastic properties of cortical bone. In this article a pair of donor femora was investigated, one with an implant and the other without. Differences in Speed of Sound (SOS), a parameter reflecting elastic properties, were measured in both femora by ultrasound transmission. As a result, in almost all areas, the femur that was implanted showed significantly lower cortical SOS. Our results indicated that the change in the mechanical function of bone, due to the introduction of femoral implants, could be evaluated by the measurement of SOS.
Preclinical and Clinical Cases of New Absorbable Composite Interference Screws in Osteoarticular Surgery
Authors: Uzel André Pierre , Elodie Seris , Henri Stephane , Jouan Gaelle , Borget Pascal , Daculsi Guy
Published: November 2012

The objective of this study deals with preclinical and clinical cases of absorbable composite interference screws of next generation in osteoarticular surgery. These implants are made of resorbable polymers PLA either amorphous or semi-cristalline, associated with granules of microporous biphasic calcium phosphate ceramic. A preclinical study was performed on goats in femoral and tibial epiphysis during 4 and 6 months. Histological and histomorphometric results were obtained by micro CT, light and scanning electron microscopy. The comparative statistical in vivo study of the kinetics of resorption and bone regeneration have shown the superiority of the composite compared to control (polymer alone). Thus the presence of Biphasic Calcium Phosphate granules in the composite has a major role for bone regeneration at the expense of the implant (buffering effect and properties of osteoconduction). An observational and functional study involving 10 patients, with a follow-up from 17 to 33 months (mean 25.7), was performed. Data were analyzed according to Good Clinical Practice and International Conference on Harmonisation. Clinical observations have revealed no complications and no serious event was reported; quantitative functional indices confirm the good observational results. The clinical study supports the functionality and performance of this new composite with properties of osteoconduction related to the osteogenicity of microporous biphasic calcium phosphate granules in the field of knee ligament fixation.
Apatite-Based Microcarriers for Bone Tissue Engineering
Authors: Feng J. , Chong M. , Chan J. , Zhang Z.Y. , Teoh S.H. , Thian Eng San
Published: November 2012

The current available microcarriers were mainly targeted towards pharmaceutical industries, and might not be suitable for therapeutic implantation. As such, apatite-based microcarriers intended for bone tissue engineering applications would be featured here. Hydroxyapatite-Alginate (HA-Alg) suspension was extruded drop-wise into a calcium chloride (CaCl2) crosslinking solution. The HA-Alg microcarriers were then sintered to form microcarriers of uniform size. The physicochemical properties were analysed by scanning electron microscopy (SEM), X-ray diffractometery (XRD), and fourier transform infrared (FTIR) spectrophotometry. Cell viability on these microcarriers was evaluated using human fetal mesenchymal stem cells (hfMSCs). SEM images revealed that sintered apatite-based microcarriers exhibited a rough surface topology with interconnected pores. XRD results showed that these microcarriers remained phase pure since no other secondary calcium phosphate phases were detected. FTIR analysis indicated several sharp phosphate bands coupled with a hydroxyl band (all belonging to HA). Live/dead staining showed that hfMSCs remained viable after 14 days of culture, and cells have spread and covered the surfaces of the microcarriers. Certainly, these cell-loaded microcarriers could be potentially used in bone implant science.
Analysis of Gene Expression and Morphology of P19 Cells Cultured in an Apatite-Fiber Scaffold
Authors: Ishii Hide , Mukai Yuya , Aizawa Mamoru , Kanzawa Nobuyuki
Published: November 2012

Heart disease is the second most common cause of mortality in Japan. Most cases of late stage heart failure can only be effectively treated by a heart transplant. Cardiac tissue engineering is emerging both as a new approach for improving the treatment of heart failure and for developing new cardiac drugs. Apatite-fiber scaffold (AFS) was originally designed as a substitute material for bone. AFS contains two sizes of pores and is appropriate for the three dimensional proliferation and differentiation of osteoblasts. To establish engineered heart tissue, a pluripotent embryonal carcinoma cell line, P19.CL6, was cultured in AFS. P19.CL6 cells seeded into AFS proliferated well. Generally, cardiac differentiation of P19.CL6 cells is induced by treating suspension-cultured cells with dimethyl sulfoxide (DMSO), after which the cells form spheroids. However, our results showed that P19.CL6 cells cultured in AFS differentiated into myocytes without forming spheroidal aggregates, and could be cultured for at least one month. Thus, we conclude that AFS is a good candidate as a scaffold for cardiac tissue engineering.
Influence of Micro-/Nano-Particles on Osteoblast-Like Cells: A Static and Time Lapse Observation
Authors: Iwadera Nobuki , Abe Shigeaki , Akasaka Tsukasa , Yawaka Yasutaka , Watari Fumio
Published: November 2012

Cytotoxicity and cell behavior to micro / nanoparticles of TiO2 and CuO was evaluated using the viability measurement and time-lapse observation. After cultured, osteoblastic cells MC3T3-E1 were exposed to particles. After 24 hour exposure, their morphology was observed using a SEM and the viability was measured. Cells exposed to TiO2 indicated no or very low decrease of viability. The results were independent of the particle size. On the other hand, the viability of cells exposed to CuO decreased with the concentration, and showed the size dependence. The nanosized CuO indicated higher toxicity compared with micro-sized one. Dynamic behavior of cells exposed to nanoparticles, was succeeded to observe in a time-lapse method for 24 hours. The observation showed that the cells exposed to CuO became dead after forming a spherical shape. This is consistent with the image taken by SEM. Time-lapse observation made it possible to see the dynamic reaction process from cell contact to particles at first, the following cell activity response and finally to cell death, which revealed a considerably different morphology from the static cell observed after fixation by conventional method.
Study of the C60 Fullerene on Differentiation of Mouse Embryonic Stem Cells
Authors: Imai Koichi , Watari Fumio , Nakamura Kazuaki , Tanoue Akito
Published: November 2012

The risks of nanomaterials for future generations should be elucidated. Thus, it is important to establish an experimental method to accurately examine embryotoxicity. We have conducted an in vitro embryotoxicity test with mouse ES cells to examine the embryotoxicities of various nanomaterials. In this study, the C60 fullerene did not influence the differentiation of ES-D3 cells and "non embryotoxicity". In the future, the biological safety should be comprehensively examined by improving dispersion in medium.
In Vitro Evaluation of Silicon-Containing Apatite Fiber Scaffolds for Bone Tissue Engineering
Authors: Kinoshita Y. , Best S.M. , Aizawa Mamoru
Published: November 2012

The aim of the present investigation was to examine Si release from the silicon-containing apatite fiber scaffold (Si-AFS) and the biocompatibility of the Si-AFS. We have successfully synthesized silicon-containing apatite fibers (Si-AF) by a homogenous precipitation method. Three-dimensional Si-AFS were fabricated using these Si-AFs. The concentrations of Si in the starting solution were 0 (AF) and 0.8 (0.8Si-AF) mass%. The 0.8Si-AFS1000 were fabricated by firing Si-AF slurry compacts (carbon/Si-AF [w/ ratio: 10/1) at 1300 °C for 5 h. Solubility experiments were carried out in 0.05 mol/dm3 Tris-HCl buffer solutions at pH 7.30 using 0.8Si-AFS1000 (porosity: ~98%), together with Si-free AFS1000 (~98%) for 21 days. The Ca2+, PO43- and SiO44- concentrations in the solution were determined by inductively-coupled plasma atomic emission spectrometry (ICP-AES). The biocompatibility of the Si-AFS was examined in vitro using osteoblastic cell, MC3T3-E1 for 21 days. The results of the ICP-AES analysis indicated that the amount of SiO44- ions released from 0.8Si-AFS1000 rapidly increased at 1 day, and then the released SiO44- ions remained constant over a period for 21 days. The cells seeded on/in the 0.8Si-AFS1000 well-proliferated as compared to those on/in the AFS1000. Consequently, we can conclude that the 0.8Si-AFS offers as a potential novel scaffold material, creating a three-dimensional cell culture environment.
Surface Design and Water Vapor-Adsorption Characteristics of Biomimetic Composite Materials Derived from Salmon Resource
Authors: Akazawa Toshiyuki , Murata Masaru , Ito M. , Nomura Takafumi , Shigyo Tatsuhiro , Sakai Katsuyoshi , Minamida Y. , Kabir Md. Arafat , Yamagishi Tohru , Iida Shunji , Nakamura Katsuo , Miyazaki Satoshi
Published: November 2012

Biomimetic composites of hydroxyapatite (HAp) and collagen with fast bio-absorption and good biocompatibility were designed utilizing salmon bone and skin at 283-293 K and pH 7.5-7.9 by a dissolution-precipitation method. Simultaneously, dissolved-precipitated HAp (dp-HA) was prepared at pH 9-10 using the calcined bone. The HAp/collagen composites (HA-C) were constituted by Ca2+-deficient HAp, I type-collagen and gelatin. At the synthetic temperature of 283 K, collagen fiber and HAp microcrystals were seen, while at 293 K, frock like-agglomerated particles or fiber like-oriented columnar ones were observed depending on the composition ratio (H/C) of HAp to collagen. Specific surface areas and total pore volumes for the HA-C synthesized at 293 K clearly increased with increasing the H/C, although there were micro-and-meso-pores in the pore diameters of 3-30 nm. Concerning water vapor-adsorption isotherms at 298 K for the HA-C powders, hysteresis-curves of the amounts of water vapor adsorbed (V) were recognized in the adsorption-desorption processes. The V values increased with increasing the H/C under the low relative pressures (P/PS) of 0-0.3 that mean monolayer-adsorption of water molecule. However, for H/C=2.2, the V values were the highest under the high P/PS of 0.70-0.90 that mean multilayer-adsorption and the biggest hysteresis-curve was found under the P/PS of 0.45-0.60, suggesting that the HA-C (H/C=2.2) powder not only adsorb water molecule on the surfaces but also absorb one into the crystal structure. Accordingly, the biomimetic HA-C powders will be applied as water-absorbable adsorption materials for cosmetic products or bone-regeneration therapy.
Effects of Heat Treatment on Apatite Formation of CaO-SiO2-PEEK Composites
Authors: Cho S.B. , An E.M. , Lee Sujeong , Jang H.D. , Kim Ill Yong , Ohtsuki Chikara , Kim Y.J.
Published: November 2012

Osteoconductive bone-repairing materials with mechanical properties analogous to those of human bone can be prepared through the combination of an osteoconductive ceramic filler with an organic polymer. Osteoconduction is archived from apatite formation on substrates. Previously, we reported that novel osteoconductive spherical particles in a binary CaO-SiO2 system were produced through a sol-gel process as ceramic filler for the fabrication of composites. In this study, we fabricated the composites consisting of polyetheretherketone (PEEK) and 30CaO·70SiO2 (CS) spherical particles and evaluated the effects of heat treatment in the range of 320-360 °C on apatite formation of the composites in a simulated body fluid. The prepared composites of PEEK and CS particles form hydroxyapatite on their surfaces in the simulated body fluid. The induction periods of hydroxyapatite on the composites decreased with increasing the amount of CS particles and decreasing the temperature for heat treatment. The apatite formation was affected by exposure of ceramic filler on the polymer matrix.
Behavior of Human Blood Adsorption to Biomimetic Functionally Graded Hydroxyapatite
Authors: Tazaki Junichi , Yodogawa S. , Murata Masaru , Ito K. , Akazawa T. , Hino J. , Kabir Md.A. , Nagayasu H. , Arisue M. , Shibata T. , Hanawa T.
Published: November 2012

Our approach to the design of biological material scaffolds for bone regeneration is the creation of cell environments that mimic natural tissues. Recently, we confirmed hitologically that the material surfaces of conventional, nonabsorbable ceramics shed body fluid. For bone engineering, it is known that ideal scaffolds should be bioabsorbable, mimetic, and hydrophilic materials that allow for the permeation of liquid components, such as blood and/or extracellular fluid. In our previous study showed functionally graded hydroxyapatite (fg-HAp) absorbed body fluid including albumin. In this study, we investigated the behavior of human blood adsorption to the fg-HAp by using the scanning electron microscope (SEM). The adsorption of the platelets and the formation of the fibrinous network were observed in the fg-HAp group incubated 20 minutes.
Therapeutic Effect of Lipophilic and/or Hydrophilic Zinc Related Compound Injections on Alveolar Bone Mass in Zinc-Deficient Osteoporosis Rats
Authors: Otsuka Makoto , Tokudome Yoshihiro , Otsuka Kuniko , Ito Atsuo
Published: November 2012

The purpose of this research is improvement of therapeutic treatment for periodontitis by using lipophilic and/or hydrophilic zinc materials. The sample suspension injections were prepared from zinc octanate, zinc stearate, zinc sulfate hepta-hydrate and tricalcium phosphate containing 6.17w/w% zinc. After administrating of all injections to around alveolar bone of zinc-deficient osteoporosis rats, plasma Zn concentration, bone mineral content and bone mechanical strength of jawbone and femur of Zn deficient rats were measured as therapeutic scores.
Adsorption of Alendronate onto Biomimetic Apatite Nanocrystals to Develop Drug Carrier Coating for Bone Implants
Authors: Bosco Ruggero , Iafisco Michele , van den Beucken Jeroen , Leeuwenburgh Sander C.G. , Jansen John A.
Published: November 2012

The possibility to develop a bone implant with bioactive aspects and in situ drug-delivery properties, in order to provide local treatment in vivo, is a big challenge. Where conventional surface modifications for bone implants focused on the deposition of ceramic (mostly calcium phosphate, CaP) coatings, current surface engineering approaches attempt to incorporate active features to render bone implant surfaces capable to direct biological performance. Biomimetic apatite nanocrystals (nAp) represent, among the CaPs, an elective material for bone applications and their surface functionalization with drugs allows them to act as a drug-delivery vehicle. Since load-bearing bone implants are increasingly used in patients with compromised health conditions, surface engineering is important to warrant the performance of these implants under such conditions. In view of this, bisphosphonates (BPs) represent a treatment modality for a variety of disorders of bone metabolism associated to bone loss, including Paget's bone disease, osteoporosis, fibrous dysplasia and bone metastases. In this work, we have synthesized and characterized bioinspired nAp and evaluated their functionalization with alendronate. In vitro tests will be used to evaluate the efficacy of the functionalized compound to impede the formation of osteoclasts and to show that alendronate-functionalized nAp can significantly reduce osteoclasteogenesis. Finally, alendronate-functionalized nAp (FnAp) has been deposited on titanium implants via the electrospray deposition technique in order to develop inorganic-organic coatings for bone implants with improved functionality.
FGF-2-Zinc-Apatite Composite Layers on External Fixation Rod for Promoting Cell Activity
Authors: Wang Xiu Peng , Ito Atsuo , Li Xia , Sogo Yu , Oyane Ayako
Published: November 2012

FGF-2-apatite and FGF-2-zinc-apatite composite layers were formed on commercially available anodically oxidized Ti external fixation rods using FGF-2-and ZnCl2-containing supersaturated calcium phosphate solutions. The FGF-2-zinc-apatite composite layers precipitated on the Ti external fixation rods significantly enhanced proliferation of fibroblastic NIH3T3 and osteoblastic MC3T3-E1 cells in vitro.
Calcium Phosphate Coated Hydroxyapatite/Collagen Nanocomposite Membrane for Surface-Mediated Gene Transfer
Authors: Bodhak Subhadip , Kikuchi Masanori , Oyane Ayako , Sogo Yu , Tsurushima Hideo , Ito Atsuo
Published: November 2012

Calcium phosphate (CaP) coating is an effective technique for surface functionalization of biomaterials. The objective of our research is to prepare calcium phosphate (CaP) coatings on a hydroxyapatite/collagen (HAp/Col) nanocomposite and subsequently provide it with gene delivery function through the immobilization of DNA in the coating. We have specifically selected the HAp/Col nanocomposite since it has the high potential as bone substitutes due to its similar composition, nanostructure, and biological properties to those of human bone. CaP coatings consisting of different sized particles were prepared on the HAp/Col nanocomposite membrane by immersing it in supersaturaterd CaP solutions (so-called RKM solutions) with the varied Ca and P concentration levels. We immobilized DNA in the CaP coatings together with lipid and fibronectin by supplementing DNA, lipid, and fibronectin to the RKM solutions (DLF-RKM solutions). Gene transfer capability of the resulting HAp/Col nanocomposite membrane was improved with decreasing concentration level of the DLF-RKM solution. It was confirmed that the present CaP coating technique was effective in providing the HAp/Col nanocomposite membrane with gene transfer capability and that the Ca and P concentration level of the DLF-RKM solution was a controlling factor affecting the gene transfer efficiency.
Effect of Structure and Composition on Ibuprofen Drug Delivery by Calcium Phosphate Nanocarriers
Authors: Madhumathi K. , Sampath Kumar T.S.
Published: November 2012

The effect of structure and composition of calcium phosphate (CaP) nanoparticles namely hydroxyapatite (HA), calcium deficient hydroxyapatite (CDHA) with Ca/P ratio ranging from 1.33 to 1.61 and tricalcium phosphate (β-TCP), on the efficiency of nanoparticles as an ideal drug carrier have been investigated. Ibuprofen, an anti-inflammatory drug was chosen for this study. The CaP nanoparticles were prepared by microwave accelerated wet chemical synthesis method and were characterized by X-ray powder diffraction, infrared spectroscopy, and electron microscopic techniques. The loading and release profiles of ibuprofen from the nanocarriers was studied using UV-Vis spectroscopy. Maximum loading of the drug was observed in β-TCP (75%) followed by CDHA of Ca/P ratio 1.5. Both samples have same Ca/P ratio but have different crystal structure. Low amount of drug loading was observed in HA and other CDHAs which have Ca/P ratio different from 1.5. Although, all the samples exhibits sustained release of ibuprofen for about 7 days, the maximum release was also shown by β-TCP (26%). Among HA and CDHAs, the amount of ibuprofen release increases with increasing Ca/P ratio. The loading and release profile of ibuprofen drug seems to be strongly related to the Ca/P ratio and structure of CaP nanocarriers.
Phosphorylated Pullulan Bioadhesive for Regeneration and Reconstruction of Bone and Tooth
Authors: Yoshida Yasuhiro , Okihara Takumi , Nakamura Mariko , Matsumoto Takuya
Published: November 2012

A biodegradable material that bonds to hard tissues such as bones and teeth is urgently needed for medical and dental applications. However, such materials are not available in today’s clinical practice of orthopedics and dentistry. Therefore, we synthesized biodegradable phosphorylated pullulan to develop a biomaterial that combines primary properties such as high biocompatibility, good bonding potential to hard tissue, high strength, biodegradability, and osteoconductivity. The pharmacopoeial polysaccharide pullulan was chemically functionalized with dihydrogen phosphate groups. Phosphorylated pullulan was formed network by adding calcium ion, making the composite less soluble in water. Adhesive force measurement revealed that adhesiveness of the pastes before setting can be controlled through optimization of additives. In addition, histological evaluation revealed that phosphorylated pullulan-based composite possesses high biocompatibility. These results indicate that phosphorylated pullulan can be used as a key material for regeneration and reconstruction of bone and tooth.
Adhesive Strength between Flexible Hydroxyapatite Sheet and Tooth Enamel
Authors: Yamamoto Ei , Kato Nobuhiro , Nishikawa Hiroaki , Kusunoki Masanobu , Hayami Takashi , Yoshikawa Kazushi , Hontsu Shigeki
Published: November 2012

Tooth enamel cannot be reconstructed once it is destroyed immoderately. Hydroxyapatite (HAp) thin sheet can potentially be used for a novel dental biomaterial to repair the enamel. Using a pulsed laser deposition (PLD) method, we have successfully created a flexible HAp sheet of less than a few micrometers in thickness. Due to its flexibility, the HAp sheet is tightly adhered on curved surfaces at the target site. In the present study, we newly developed double-layered sheets composed of HAp film coated with tricalcium phosphate (TCP) thin layer. The HAp/TCP sheet was adhered to the extracted human teeth using a calcium phosphate solution for 3 days. The adhesive strength between the HAp/TCP sheet and tooth enamel was evaluated by quasi-static tensile tests. Moreover, the interface structure between them was observed by a scanning electron microscopy. As a result of the mechanical evaluation, the adhesive strength was greater than approximately 2.5 MPa. The electron microscopic observation revealed that the sheet was partially fused with the enamel. These findings suggest the possibility that enamel defects are repaired using the HAp/TCP sheet for a short duration.
Effects of Ammonium Hexafluorosilicate Concentration on Crystallinity of Hydroxyapatite Powder and Enamel
Authors: Suge Toshiyuki , Matsuo Takashi
Published: November 2012

Ammonium hexafluorosilicate [SiF: (NH4)2SiF6] solution was prepared in order to overcome the tooth discoloration caused by diamine silver fluoride [AgF: (NH3)2AgF] application. However, it is still unclear how the concentration of SiF solution affects the crystallinity of enamel. The aim of this study was to evaluate the effects of changing concentrations of SiF solution on the crystallinity of hydroxyapatite powder and structure of human enamel. Hydroxyapatite powder was treated with several concentrations of SiF solution (from 10 to 19,400 ppm) for five min. The crystallinity of hydroxyapatite powder before and after SiF treatment was then measured by powder X-ray diffraction (XRD) analysis. The angular width (β) of the 002 diffraction peak was measured at 1/2 the height of the maximum intensity. Also, enamel specimens were prepared from a human extracted tooth. Several concentrations of SiF solution were applied to polished or phosphoric acid etched enamel specimens. The enamel surface was then observed using scanning electron microscopy (SEM). XRD peaks became sharper after SiF treatment indicating that the crystallinity of apatite powder was increased. The 1/β value was increased from 2.8±0.1 to 4.3±0.1 after treatment with 1,000 ppm SiF solution. The amount of CaF2 formed in hydroxyapatite powder was gradually increased with increasing concentrations of SiF solution. The XRD pattern was consistent with CaF2 in case of over 9,000 ppm SiF solution. SEM photographs demonstrated that exposed enamel rods with acid etching were filled with CaF2-like precipitate after SiF treatment regardless of the concentration of SiF solution. It was concluded that SiF treatment increased the crystallinity of apatite powder and repaired the demineralized enamel surface with the formation of CaF2 or CaF2-like precipitate, and thus, SiF treatment would be useful for the prevention of dental caries.
Formation of Calcium Phosphate/Titanium Oxide/Titanium/ Plastic Composite Implant
Authors: Watazu Akira , Sakai Takuya , Teraoka Kay , Sonoda Tsutomu , Morinaga Kenzo , Kido Hirofumi
Published: November 2012

Calcium phosphate/ titanium oxide/ titanium/ plastic composite implants with 1.6-mm diameter and 7-mm length were successfully formed using a DC/ RF magnetron sputtering machine. The sample had no cracks and the surface of the sample was uniformly smooth. The chemical composition of the >10-nm-thick calcium phosphate layer was Ca: P: O=1.0: 0.79: 2.8. The sample was implanted into the tibia of an male 8-week-old SD rat for 28 days. When 0.70-μm sections of the tibia were prepared, the titanium layer with titanium oxide layer of the implant was not broken and the surfaces of the layer of the implant had not decomposed. The interaction between living bone and the implant could be clearly observed by light microscope and TEM.
Hydrothermal Modification of Products Fabricated by Electron Beam Melting
Authors: Fukuda Hidetsugu , Ueda Masato , Ikeda Masahiko , Nakano Takayoshi
Published: November 2012

Electron beam melting (EBM) method is one of the free-form fabrication techniques that enable near-net-shape manufacturing of complex three-dimensional, porous, and graded products, and is expected to facilitate the development of new methods for manufacturing biomaterials that could be used for hard-tissue substitutes. Titanium and its alloys have been used widely as biomaterials for hard-tissue substitutes because of their excellent mechanical properties and biocompatibility. However, the osteointegration of these materials is less than that of bioactive ceramics. Therefore, various surface-modiﬁcation techniques have been developed to improve the osteointegration. The simplest way is to synthesize bioactive ceramic ﬁlms on the surface of titanium or its alloys. The purpose of the present work was to synthesize a bioactive TiO2 film on Ti-6Al-4V (hereafter, abbreviated as Ti-64) substrates fabricated from powders using the EBM method and treated by a combination of chemical and hydrothermal treatment. Ti-64 plates fabricated by the EBM method were chemically treated with a H2O2/HNO3 aqueous solution under appropriate conditions. The plates were then hydrothermally treated with a NH3 aqueous solution. TiO2-gel films were produced by chemical treatment with a H2O2/HNO3 aqueous solution on the surface of a Ti-64 substrate. Anatase-type TiO2 ﬁlms with high crystallinity were synthesized by the hydrothermal treatment of the TiO2-gel ﬁlms.
Effect of Polarization Treatment Time on Inhibition of Low Temperature Degradation in Y-Doped ZrO2
Authors: Tsuchiya Yu , Horiuchi Naohiro , Nakamura Miho , Nozaki Kosuke , Nagai Akiko , Hashimoto Kazuaki , Yamashita Kimihiro
Published: November 2012

Effect of surface charges induced by polarization treatment on Low Temperature Degradation (LTD) in 3mol%Y-doped ZrO2 was studied. Samples were polarized by applying voltage (7kV/cm) at 200°C for various time (1~30min). LTD acceleration test was conducted using polarized samples. LTD was inhibited on negatively charged surface in all the polarized samples, which is independent on polarization time. We carried out thermally stimulated depolarization current (TSDC) analysis for investigate polarization mechanism. Two polarization elements were confirmed: orientation polarization and space charge polarization. A comparison of the result of LTD acceleration test and TSDC analysis indicates that orientation polarization is considered superior element in inhibition of LTD.
Laser Vaporization of Magnetic FexOy and FexOy-SiO2 Nanoparticles for Biomedical Applications
Authors: Stötzel Christian , Kurland Heinz Dieter , Grabow Janet , Müller Frank A.
Published: November 2012

Magnetic iron oxide (FexOy) and iron oxide/silica (FexOy/SiO2) composite nanoparticles were synthesized by CO2 laser vaporization (LAVA) of an α-Fe2O3 raw powder and α-Fe2O3/quartz sand mixtures, respectively. Particle morphology, composition and iron oxide phase formation were investigated by transmission electron microscopy and X-ray diffraction. The resulting nanopowders mainly consisted of magnetite (Fe3O4) and maghemite (γ-Fe2O3). Increasing the oxygen partial pressure in the LAVA process gas an additional iron oxide phase, ε-Fe2O3, occurred. The saturation magnetization of the iron oxide nanoparticles was determined with vibrating sample magnetometry and was found to decrease with increasing oxygen partial pressure in the process gas. FexOy/SiO2 composite nanoparticles are of particular interest for biomedical applications because their silica surface can be functionalized very easily.
Time-Dependent Protein Adsorptive Behavior on/in Mesoporous Silica Materials
Authors: Yokogawa Yoshiyuki , Yamato Yuta , Ito Shinji , Nakamura Atsutomo , Kishida Ippei
Published: November 2012

The Time – Dependent Adsorptive Behavior of Biomolecules on/in Mesoporous Silica Materials (MPS) Have Been Studied by Using Transmission Electron Microscopy (TEM). Highly Ordered Hexagonal Mesoporous Silica Materials (SBA-15) Synthesized Were Immersed in Phosphate Buffer Saline (PBS) Solution Containing Cytochrome C for 2, 48, and 120 Hours at 4 °C. after that, MPS Materials Were Rinsed with PBS Solution, and then Immersed in PBS Solution without Cytochrome C. the Amount of Protein Adsorbed on/in MPS Materials Soaked for 2, 48, and 120 Hours Was 75 Mg/g, 135 Mg/g and 178 Mg/g, Respectively. the Time Profiles for Adsorption of Proteins Can Be Well Described by Intraparticle Diffusion Model. the Holes of MPS Materials Were Observed to Be Overlapped with Stained Proteins for First 2 Hours Immersion. the Stained Proteins Were Observed between Primary Particles and Partly inside the Mesoporous Channels in the MPS Material Immersed for 48 Hours. for MPS Immersed for 120 Hours, Stained Proteins Were Observed in Almost All Meso-Scale Channels of MPS. the Ratio of Desorbed Proteins from those Embedded on/in MPS Materials Was 13 % in Case of the MPS Materials Immersed in PBS Containing Cytochrome C for 2 Hours, while 8 % in Case of the MPS Materials Immersed for 48 and 120 Hours. Cytochrome C May Be Strongly Embedded on/in MPS Materials due to the Electrostatic Effect.
The VSC Adsorption on Hydrotalcite through Topochemical Reactions
Authors: Yokogawa Yoshiyuki , Yagi Yutaro , Sano Hroya , Nakamura Atsutomo , Kishida Ippei
Published: November 2012

Volatile sulfur compounds (VSCs) such as hydrogen sulfide (H2S), methyl mercaptan and dimethyl sulfide produced in mouth. Some oral (Gram-negative) bacteria produce VSCs, which induces permeability of mucous membrane, cause the oral malordor, dental caries, color change of the dental fillings. Thus, material which adsorbs VSCs should be useful to keep health in mouth. Previously, we reported the H2S adsorptive properties of zeolite and hydrotalcite materials having micro pores. The amount of H2S adsorbed on the zeolite or hydrotalcite at room temperature was found to be around 300-400 ppm, and and 3 % of H2S was desorbed when heated at 400 °C. The hydrotalcite, whose compositon is Mg1-xAlx(OH)2Ax/n·mH2O, where A is CO32-, and x is 0.25, was heat-treated at 500 °C, and put into aqueous solution containing H2S. In this study, the relation between heat-treatment tempearture and the sulfide adsorption on hydrotalcite in aqueous solution was investigated. The hydrotalcite materials were hydrothermally synthesized and identified by powder X-ray diffraction method. The change in concentrations of H2S in aqueous solution was measured using FPD gas chromatography (GC). The concentrations of H2S was decreased with time for the hydrotalcite heated at 500 °C or 600 °C, and fell to 20 % for 12 hours. But, the concentration was decreased by 40% for 12 hours for the hydrotalcite materials heated at higher temperatue. XRD and FT-IR analysis revealed that the sulfides were into or out of the hydrotalcite structure through topochemical reactions.
The Size Control of Hydroxyapatite Particles during Spray Pyrolysis
Authors: Cho Jung Sang , Rhee Sang Hoon
Published: November 2012

The size of hydroxyapatite particles during spray pyrolysis was successfully controlled by varying the concentrations of the starting calcium phosphate (CaP) solutions. Three different concentrations of CaP solutions were prepared by dissolving Ca (NO3)2·4H2O and (NH4)2HPO4 into deionized water and then they were sprayed at 900°C with the carrier gas flowing rate of 10 L/min. The size of the resultant hydroxyapatite particles decreased as lowering the concentration of the starting CaP solution. The smaller the particle size, the higher the relative density of the hydroxyapatite disks after sintering at 1100°C for 1 hour. The practical implication of the results is that highly sinterable hydroxyapatite particles can be synthesized during spray pyrolysis by controlling the starting concentration of CaP solution.
Synthesis and Characterisation of Strontium and Magnesium Co-Substituted Biphasic Calcium Phosphates
Authors: Imrie Flora E. , Aina Valentina , Lusvardi Gigliola , Malavasi Gianluca , Gibson Iain R. , Cerrato Giuseppina , Annaz Basil
Published: November 2012

Magnesium and strontium both play important roles in the growth of bone and so are desirable ions for substitution into hydroxyapatite (HA) intended for use as bioinstructive bone substitutes. A range of compositions were prepared by a solid state method based on the nominal composition of HA (Ca10(PO4)6(OH)2), with various levels of strontium and/or magnesium substitution: strontium-substituted HA (Ca8Sr2(PO4)6(OH)2), magnesium-substituted HA (Ca9.8Mg0.2(PO4)6(OH)2 and Ca9Mg (PO4)6(OH)2), and strontium and magnesium co-substituted HA (Ca7.8Sr2Mg0.2(PO4)6(OH)2 and Ca7Sr2Mg (PO4)6(OH)2). Materials were characterised by powder X-ray diffraction, Fourier-transform infrared spectroscopy and Raman spectroscopy. These analyses indicated that the co-substituted materials were composed of mixtures of strontium-substituted hydroxyapatite and magnesium and strontium co-substituted β-tricalcium phosphate. In the magnesium-substituted materials, increased magnesium content was related to increased proportion of β-tricalcium phosphate phase, both with and without strontium co-substitution. The unsubstituted and strontium mono-substituted materials, however, were pure apatite phase, suggesting that magnesium was the destabilising factor in the phase compositions of the magnesium mono-substituted and magnesium and strontium co-substituted materials.
Annihilation Characteristics of Confined 2D Positronium
Authors: Dryzek Jerzy , Lewicka Sylwia
Published: November 2012

The 2D Positronium (2D Ps) atom confined in the 2D cave has been considered and its properties were compared with the 3D Positronium located in the infinity square well potential. Basing on the solution of Schrödinger equation for the 2D hydrogen atom the wave function of the 2D Ps was given. It allows us to calculate, for instance the angular correlation of the annihilation radiation (ACAR) of such a system. It was shown that the ACAR is much broad than ACAR for the 3D Ps and that for the Ps in the bubble model.
Hexadecane in SiO2 Aerogels
Authors: Sláviková Barbora , Miklošovičová M. , Illeková E. , Majerník V. , Šauša O. , Krištiak J. , Jesenák K.
Published: November 2012

This work deals with the use of positron annihilation lifetime spectroscopy (PALS) for the study of hexadecane confined in SiO2 aerogel. The temperature dependencies of the o-Ps lifetime and intensity for this material were compared with values of hexadecane confined in silicagel with a similar average pore size. The results of differential scanning calorimetry (DSC) for both these materials will be discussed.
Phase Transition of Water Confined in Saponites Using Positron Annihilation Spectroscopy
Authors: Maheshwari Priya , Sharma Sandeep Kumar , Dutta Dhanadeep , Sudarshan Kathi , Pujari P.K.
Published: November 2012

The temperature dependent Positron lifetime and Doppler broadening spectroscopy have been carried out to study the phase transition of water confined in interlamellar spaces of saponite clay in the temperature range 300K-200K. The change in slope/discontinuity in S-parameter and Ps lifetime as a function of temperature is an indication of phase transition. Two phase transition temperatures viz. above and below the bulk freezing temperature have been observed for water confined in saponite clay. This indicates the presence of two regimes of water confined in interlamellar spaces. The freezing-melting cycle is also marked by significant hysteresis.
Topological Quasi-Positroniums in Graphite-Alkali Metal Intercalation Compounds
Authors: Saito Makoto , Yamada Kouhei , Kanazawa Ikuzo
Published: November 2012

We have analyzed the positron annihilation Angular Correlation data in the second stage graphite-potassium intercalation C24K with the theoretical formula extended from "topological quasi-positronium model" and have proposed one of the possible origins of the anisotropic narrow component in alkali-metal graphite intercalations compounds (AGICs).
In Situ Positron Lifetime Measurement for the Strained Polyethylene
Authors: Fujinami Masanori , Minei Ryutaro , Liu Chang Gui , Hara Kenta
Published: November 2012

The in situ positron annihilation spectroscopy measurement has been developed and applied to investigate the structural change in free volume on the tensile deformation of linear low-density polyethylene. The pick-off lifetime of ortho-positronium (Ps) decreases by applying the strain and an aging variation cannot be observed. On the contrary the fraction of Ps formation gradually decreases day by day and becomes constant after several days. Further, after release of strain, it returns to the original value. The reason is considered to be that the molecular chains become rigid gradually during deformation and they lose the flexibility.
Positron Annihilation Lifetime of Irradiated Polyimide
Authors: Hirade Tetsuya , Oka Toshitaka , Morishita Norio , Idesaki Akira , Shimada Akihiko
Published: November 2012

Ortho-positronium pick off annihilation lifetime gives the information of the microscopic free volume of polymers. Polyimide polymers such as Kapton are applied in many fields, but it was impossible to apply the positron lifetime method for free volume investigation because of no positronium formation. Here, we apply the idea of the free positron annihilation probability that is sum of the probability of annihilation by the positron and electrons on the molecular chain where the positron localized and that for the annihilation with the electrons on the neighboring molecular chains. The second term is probably affected by the free volume change. We have successfully shown the temperature dependence and the electron beam irradiation effect on the free volume change by observing the free positron annihilation lifetime for Kapton.