Bio-Medical Materials and Engineering - Volume 19, issue 1
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Bio-Medical Materials and Engineering is to promote the welfare of humans and to help them keep healthy. This international journal is an interdisciplinary journal that publishes original research papers, review articles and brief notes on materials and engineering for biological and medical systems.
Articles in this peer-reviewed journal cover a wide range of topics, including, but not limited to: Engineering as applied to improving diagnosis, therapy, and prevention of disease and injury, and better substitutes for damaged or disabled human organs; Studies of biomaterial interactions with the human body, bio-compatibility, interfacial and interaction problems; Biomechanical behavior under biological and/or medical conditions; Mechanical and biological properties of membrane biomaterials; Cellular and tissue engineering, physiological, biophysical, biochemical bioengineering aspects; Implant failure fields and degradation of implants. Biomimetics engineering and materials including system analysis as supporter for aged people and as rehabilitation; Bioengineering and materials technology as applied to the decontamination against environmental problems; Biosensors, bioreactors, bioprocess instrumentation and control system; Application to food engineering; Standardization problems on biomaterials and related products; Assessment of reliability and safety of biomedical materials and man-machine systems; and Product liability of biomaterials and related products.
Abstract: The interactions between carbon nanotubes and important biomolecules, above all collagen molecules, have not been studied in detail. This situation is partly due to the fact that CNT are solid entities, while most of the biomolecules can be prepared in solution. We used turbidity as a means of evaluating the interaction between CNT and collagen molecules. To a stable suspension of CNT (10 ppm in 0.1% Triton), collagen solution was added to obtain a final concentration of 25 ppm. The degree of aggregation was evaluated by measuring the turbidity of the suspension at 660 nm. It was found that native…collagen induced distinct aggregation with CNT, while denaturation of this protein at 60°C for 1 hr deprived the molecules of their ability to aggregate with CNT. Also other globular molecules, albumin and lysozyme, did not induce aggregation of CNT. These results indicate that the rigid rod-like structure of the native collagen triple helix is essential for interaction with CNT to cause aggregation. The mechanisms are considered to be dependent upon geometric properties of rod-like collagen molecules. The findings in this paper will open a new avenue to clarify the detailed mechanism of the interaction between collagen molecules and CNT.
Abstract: Three types of multiwalled carbon nanotube (MWCNT) monoliths without any binders were obtained by spark plasma sintering (SPS) treatment at 2000°C under 80 MPa sintering pressure. Three MWCNTs with different diameters: thin (∅20–30 nm, CNT Co., Ltd., Korea), thick (∅100 nm, Nano Carbon Technologies Co., Ltd., Japan) and spherical thin (∅20–30 nm, granulated diameter = 1–3 μm, Shimizu Corporation, Japan) were employed for SPS. SEM observation confirmed that these materials maintained the nanosized tube microstructure of raw CNT powder after SPS treatment. The densest monolith was prepared with the spherical MWCNTs. The mechanical properties of this material were estimated by…the dynamic hardness test. The elastic modulus of the monolith did not depend on the difference of MWCNTs, but the hardness of spherical MWCNTs was higher than that of thick MWCNTs. The high density and hardness of the spherical MWCNTs were caused by the high packing density during the SPS process because of its spherical granulation. Thus, the spherical MWCNTs were most useful for the MWCNT monolith preparation with the SPS process and its application as a bone substitute material and a bone tissue engineering scaffold material was suggested.
Abstract: To evaluate the role of particle size in cytotoxicity tests of nanomaterials (NMs), we exposed Chinese hamster cells to polystyrene (PS) spheres with defined diameters ranging from 0.1 to 9.2 μm. We found that the 4.45-μm PS particles were most cytotoxic while sizes 0.1 and 0.2 μm showed no cytotoxicity up to 1000 μg/ml. In the chromosome aberration test, the 4.45-μm PS particles induced polyploidy in a mass concentration-dependent manner in 24- and 48-h treatments. The 5.26-μm PS particles induced polyploidy only at 1000 μg/ml for 48 h. Next, we performed the cytotoxicity test with as-grown single walled carbon nanohorns…(NHas). These were suspended in DMSO and then transferred into the culture medium followed by sonication. Six suspensions differently sonicated showed the same apparent toxicity, although the total particle size distributions differed. However, the sizes of NHas particles predicted to be most toxic from the experiments with PS particles, i.e. 1.01–4.47 μm constituted 40–60% of all particles in all six suspensions. The results suggest that the cytotoxicity of NMs in suspension depends on specific sizes of aggregates and therefore suspensions should be checked with regard to particle size distributions in assays of toxic effects. The uptake of particles into cells was confirmed by confocal microscopy.
Abstract: In-situ TEM (transmission electron microscopy) of silver nanoparticle ink at high temperature was carried out. Into a carbon film tube coating the spiral tungsten filament which was attached to the TEM specimen holder, a silver nanoparticle ink was injected. After evaporation, silver nanoparticles with an aggregated structure could be observed. The temperature of the tungsten wire can be controlled by DC current supplied by dry batteries. Fusion of smaller nanoparticles was observed at a higher temperature and some particles were incorporated to larger particles. This technique can be generally used to consider the sintering temperature of such metal nanoparticles.
Keywords: In-situ TEM, silver, nanoparticle, conductive ink, melt
Abstract: Arrays of Carbon nanofibers (CNFs) harness the advantages of individual CNF as well the collective property of assemblies, which made them promising materials in biosensing and tissue engineering or implantation. Here, we report two studies to explore the applications of vertically aligned CNFs. First, a nanoelectrode array (NEA) based on vertically aligned CNFs embedded in SiO2 is used for ultrasensitive DNA detection. Oligonucleotide probes are selectively functionalized at the open ends of the CNFs and specifically hybridized with oligonucleotide targets. The guanine groups are employed as the signal moieties in the electrochemical measurements. Ru(bpy)3 2+ mediator is used…to further amplify the guanine oxidation signal. The hybridization of less than ~1000 molecules of PCR amplified DNA targets are detected electrochemically by combining the CNF nanoelectrode array with the Ru(bpy)3 2+ amplification mechanism. Second, the SiO2 matrix was etched back to produce needle-like protruding nanoelectrode arrays to be used as cell interfacing fibers for investigating gene transfection, electrical stimulation and detection of cellular processes. Our goal is to take advantage of the nanostructure of CNFs for unconventional biomolecular studies requiring ultrahigh sensitivity, high-degree of miniaturization and selective biofunctionalization.
Abstract: Carbon nanotubes (CNTs) have excellent chemical durability, mechanical strength and electrical properties. Therefore, there is interest in CNTs for not only electrical and mechanical applications, but also biological and medical applications. We coated titanium, a common material for dental implants, with multiwalled carbon nanotubes (MWCNTs). First, titanium was aminated and covered with collagen. Then, the carboxylated MWCNTs were coated onto the collagen attached to the titanium plate. The collagen-coated titanium plate had a homogeneous MWCNT coating, which showed strong attachment to the titanium surface as a thin layer. The surface roughness was significantly increased with the MWCNT coating. MC3T3-E1 cells…were cultured on the MWCNT-coated Ti plate, and showed good cell proliferation and strong cell adhesion. Therefore, the MWCNT coating for titanium could be useful for improvement of cell adhesion on titanium implants.
Abstract: Some metallic materials in dental prostheses may cause allergic hypersensitivity. Symptoms appear not only in the oral cavity, but also on hands, feet or the entire body. Release of metal ions is thought to cause the allergic reactions; micro-particles of the corrosion products of the metal and/or ionic metal hydroxides/oxides may be the allergens. The study purpose was to review clinical surveillance of dental allergic hypersensitivity in our dental hospital. From July 2000 to June 2005, 212 patients with suspected dental metal allergy were patch tested with 26 reagents, including 19 ready-made patch test reagents (Patch test reagents™, Torii Pharmaceutical…Corporation, Tokyo, Japan) and 9 custom-made reagents. One-hundred-and-sixty-seven patients were females (78.8%) and 45 patients were males (21.2%). A total of 148 patients (69.8%) had one or more positive patch test reactions. The most common allergens were nickel (25.0%), palladium (24.4%), chromium (16.7%), cobalt (15.9%) and stannum (12.5%). Typical allergic symptoms and diagnoses were Pustulosis palmaris et plantaris, lichen planus, stomatitis and contact dermatitis. This study indicates that dentists and dental researchers should be concerned about the allergenic potential of dental metal materials.
Keywords: Allergic reactions, dental materials, patch test
Abstract: The purpose of this study was to examine gene expressions of macrophage phagocytizing sub-μ Ti particles by a DNA chip. Human monocytic cell line THP-1 was differentiated into macrophages by culturing for two days in medium supplemented with 200 nM phorbol ester (PMA). The macrophages were then cultured in four media: medium without PMA (control); medium with suspended sub-μ Ti particles (0.5 wt%); medium with 1.0 μg/ml lipopolysaccharide (LPS); and medium with LPS and Ti particles. After 6 hours' culture, total RNA were extracted and gene expressions were evaluated by DNA allergy chip with 205 allergy and inflammation related gene…spots. We found that phagocytosis of sub-μ Ti particles and LPS independently and synergistically up-regulated 17 inflammation-related genes more than two-fold. The extensive expressions of four genes (CCL1, IL1B, IL6 and IL8) were further confirmed by real-time quantitative PCR. It turned out that dual stimulation of LPS and Ti particles most up-regulated three genes (IL1B, IL6 and IL8), followed by LPS while Ti particles moderately but least increased, suggesting that phagocytosis of sub-μ Ti particles induces moderate inflammation with its degree less than LPS, but phagocytosis of sub-μ Ti particles has the potential to worsen inflammation caused by LPS-stimulated macrophages.
Abstract: A new biphasic calcium phosphate ceramic material has been developed in our laboratory. It is composed of 60% of hydroxyapatite and 40% of β-tricalcium phosphate, based on three granulometries (submicron, round microporous 80–200 μm and macro microporous 0.5–1 mm particles) and hydrated with water leading the formation of a putty filler for bone repair. Biocompatibility and osteogenicity were tested by filling femoral epiphyses critical size bone defect and lumbar muscles in rabbit. After 3, 6 and 12 weeks of implantation, explants were treated for histology. Results revealed the biocompatibility of the material and intensive resorption of the submicron particle fraction…followed by important bone ingrowth whereas osteoconduction was provided by the larger particles.
Keywords: Biphasic calcium phosphate, ceramic, nano-microparticles, resorption, bone ingrowth
Abstract: TiO2 nanotube array (TN) on titanium plate was fabricated by using an electrochemical method. The crystal structure and surface morphology of TN array was examined by X-ray diffraction (XRD) and Field Emission Scanning Electronic Microscopy (FE-SEM), respectively. The stability of the nanotube structure and crystal phase transition was studied at different temperatures in dry oxygen ambient. The as-deposited films were found to be amorphous. The tubes crystallized in the anatase phase at a temperature of 450°C. Anatase crystallites formed inside the tubes walls was transformed completely to rutile at 500°C in dry environment. With the heating temperature increased the…intensity of rutile peak increased with decrease in reflection from titanium. Intense rutile peak was observed at 600°C. The average pore diameter as calculated from FE-SEM images was 50–100 nm. At higher temperature tubular structure completely collapsed leaving dense rutile crystallites. A model was proposed to explain the formation mechanism of TN fabricated on titanium plate in HF/H2 SO4 electrolyte.