Bio-Medical Materials and Engineering - Volume 19, issue 2-3
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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: An acid–base resistant zone (ABRZ) has been shown to be created under a hybrid layer in a self-etching adhesive system at the adhesive/dentin interface. The purpose of this study was to assess the nanostructure of the ABRZ by applying all-in-one adhesive systems. Human premolar dentin was treated with one of two all-in-one adhesive systems; Clearfil Tri-S Bond and G-Bond according to the manufacturers' instructions. After placement of a resin composite, the bonded interface was vertically sectioned and subjected to an acid-base challenge. Following this, the nanostructure of the ABRZ was examined by SEM and TEM. The SEM observations of the…adhesive-dentin interface after the acid-base challenge indicated that a hybrid layer less than 1 μm thick was created, and a ABRZ was formed beneath the hybrid layer for each adhesive system. The TEM observations indicated that the ABRZ contained mineral components in both adhesive systems, however, the thickness of the ABRZ was material dependent. The application of the all-in-one adhesive systems created an ABRZ at the underlying dentin, which reinforced normal dentin against dental caries. Therefore, this zone was named ‘Super Dentin’. Formation of ‘Super Dentin’ is a new approach in caries prevention.
Abstract: Finely powdered enamel was used to develop a prosthetic resin composite that has good mechanical properties and no potential to abrade opposing tooth structure. Bovine teeth were ground into powder and then the enamel particles were separated from the powder by centrifugation in bromoform–ethanol solution. The resin matrix consisted of UDMA (60 mole %) and Tri-EDMA (40 mole %). Camphorquinone (0.5 mass %) was added to the monomer as a photo-initiator. Fillers were incorporated directly into the resin matrix in amounts of 80 or 85 mass %. The flexural strength and Vickers hardness (Hv ) were measured. The average flexural…strength and Hv values for specimens having 85 mass % filler that had been subjected to heat treatment at 100°C after light-curing were 95.2 and 109.8 MPa, respectively, which are higher than those for most commercial prosthetic resin composites. These findings suggest that a novel prosthetic resin composite with good mechanical properties can be made by loading finely powdered enamel into the resin matrix.
Abstract: Recent studies have shown that carbon nanotubes (CNTs) can be used as biomedical materials because of their unique properties. CNTs effect nucleation of hydroxyapatite, because of which considerable interest has been generated regarding the use of CNTs in dentistry. However, there are only a few reports on the use of CNTs as dental materials. In this study, we investigated the changes induced in the surfaces of tooth slices by the application of a coating of CNTs by observing CNT-coated tooth slices both macroscopically as well as under a scanning electron microscope. Further, we investigated the effect of CNT coating on…the tensile bond strength of dentin adhesives. CNTs adhered easily to the tooth surfaces when tooth slices were suspended in a CNT-dispersed solution. Interestingly, it was observed that CNTs selectively adhered to the surfaces of dentin and cementum, possibly by adhering to their exposed collagen fibers. In addition, the CNT coating did not affect the tensile bond strength of dentin adhesives. These results indicate that coating of the teeth with CNTs can be a possible application of CNTs as dental materials.
Abstract: The volatile organic compound (VOC) reduction activity of scallop shell powders fired at 300, 600 and 900°C was examined using formaldehyde (HCHO). Raw shells as well as fired shells immediately after firing at several temperatures, except for 600°C, were found to gradually remove HCHO from the air. In the case of shell powders stored for 3 months after firing, the HCHO reduction activity of the powder fired at 900°C was obviously improved, with the HCHO concentrations rapidly reaching zero within 20 min. It has been found by X-ray diffraction measurements that shell powder stored for 3 months after firing at…900°C contains a small amount of calcium hydroxide (Ca(OH)2 ) generated from calcium oxide (CaO). Our results suggest that Ca(OH)2 may be the effective ingredient in the HCHO reduction.
Abstract: The purpose of this study was to determine the effects of heat treatment on the bioactivity of hydrothermal-modified titanium in CaO solution for improved bioactivity by immersion in simulated body fluid (SBF). The hydrothermal treatment of titanium in CaO solution was performed at 121°C at 0.2 MPa for 1 h in an autoclave followed by 1 h heat treatments at 200, 400, 600 and 800°C simultaneously. The bioactivity of titanium was evaluated by hydroxyapatite precipitation during immersion in SBF. Surface microstructure changes after the heat treatments and immersion in SBF were determined by X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS),…and scanning electron microscopy (SEM). Heat treatments at high temperatures (600 and 800°C) promoted the synthesis of anatase, increased the thickness of the titanium oxide layer on the modified titanium surface and promoted the synthesis of calcium titanate, which possibly promoted the precipitation of apatite in SBF. The extent of precipitations increased with the time of immersion in SBF and the temperature of the heat treatment. Island-like deposits of needle-like crystals were observed only on the surface of the 600 and 800°C heat-treated specimens after two or four week immersions in SBF. The results suggested that treatments of the surface of hydrothermal-treated titanium specimens at high temperatures (600 and 800°C) could be effective for the surface modification of titanium as an implant material offering better osseointegration.
Abstract: The effect of temperature on crystallinity of carbonate apatite (CAp) foam prepared from α-tricalcium phosphate (α-TCP) foam by hydrothermal treatment was investigated in the present study. The α-TCP foams were prepared through a conventional sintering method using polyurethane foam as template. Then, the resultant α-TCP foams were hydrothermally treated with Na2 CO3 aqueous solution at 100°C, 150°C and 200°C for 72 h. After hydrothermal treatment, the cancellous bone-like macroporous structure of the α-TCP foams was maintained. However, microscopic morphology of the foams' frame significantly changed after the 72 h treatment period. The smooth surface of α-TCP foam disappeared and…the whole surface was covered with plate-like deposits. The plate-like deposits treated at 150°C and 200°C had smooth surface while those treated at 100°C were constructed from spherical particles of approximately 200 nm in diameter. The results of X-ray diffraction and Fourier transform infrared analysis showed that α-TCP was completely converted to CAp and the crystallinity of CAp prepared at 100°C was significantly lower than those prepared at 150°C and 200°C. Hydrothermal treatment of α-TCP foam at 100°C allowed the formation of low-crystalline CAp foam but complete conversion needs a longer treatment period.
Abstract: Nano-sized particles have received much attention in view of their varied application in a wide range of fields. For example, magnetite (Fe3 O4 ) nanoparticles have been investigated for various medical applications. In this study, we visualized the distribution of administered magnetic nanoparticles in mice using both X-ray scanning analytical microscopy (XSAM) and magnetic resonance imaging (MRI). After administration, the nanoparticles were rapidly dispersed via the blood circulation, and reached the liver, kidney and spleen. Using the XSAM and MRI methods in a complementary fashion, the biodistribution of nano-sized magnetite particles was successfully visualized.
Keywords: Biodistribution, magnetic resonance imaging, nano magnetite
Abstract: We observed the internal diffusion behavior of inorganic micro/nano particles through oral administration. By oral exposure, the fed particles were absorbed through the digestive system then reached some organs after internal diffusion in the body. For example, TiO2 particles fed to mice were detected in the lung, liver, and spleen after 10 days of feeding. Whereas, the absorption efficiency was extremely low compared with intravenous injection. In a comparison of the simple amount of administration, oral exposure required 102 times or more amount by intravenous injection for detection by an X-ray scanning analytical microscope. During dental treatment, micro/nano…particles from tooth or dental materials would generate in the oral cavity, and some of the particles had a possibility to be swallowed, absorbed through the digestive system, and then diffuse into the body. However, our results suggest that biocompatible microparticles that are naturally taken orally affect animals only rarely because of the low absorption efficiency.
Abstract: Asbestos minerals are thin fiber type of minerals and honorably said as “the minerals of the miracle” because of their valuable natures even in the strategic field. On the other hand, the relation between asbestos exposure and diseases such as lung cancer and malignant mesothelioma was proved around 1970 by epidemiology and an animal experiment in relation to their microstructures. Here, microstructures of chrysotile asbestos, a mainstream of asbestos substances, are shown. It is also shown that in what kinds of environment people are exposed to asbestos and what kinds of biological or epidemical things happen after asbestos exposure. Many…kinds of fibrous materials as the substitutes of asbestos are described in relation to their carcinogenicity.
Keywords: Structure of asbestos, biological influence of asbestos exposure, asbestos substitutes
Abstract: Transfection is a widely used method in molecular biology for the introduction of foreign nucleic acids (DNA or RNA) into eukaryotic cells that permits to control intracellular processes, i.e. the induction or inhibition of protein expression. Nucleic acids alone cannot penetrate the cell membrane, therefore special carriers like cationic polymers or inorganic nanoparticles are required. Single-shell and multi-shell calcium phosphate nanoparticles were prepared and functionalized with DNA and siRNA. Thereby, the expression of enhanced green fluorescing protein (EGFP) can be induced (by using pcDNA3-EGFP) or silenced (by using siRNA). The single-shell nanoparticles were prepared by rapid mixing of aqueous solutions…of calcium nitrate and diammonium hydrogen phosphate. The multi-shell nanoparticles were produced by adding further layers of calcium phosphate and DNA to protect DNA from the intracellular degradation by endonucleases. The size of the nanoparticles according to dynamic light scattering and electron microscopy was up to 100 nm with a zeta potential around −30 mV. The transfection efficiency of the nanoparticles was tested in vitro in cell culture.