Weeks Of Soaking Research Articles

2822 骨置換能を有するセラミックス複合材料の作製とその特性(J08-2 バイオメカニクス,J08 生体・環境適合材料の創製・強度評価技術開発)

A material for medical application is required to have extended sustainability of mechanical strength together with fast bone replacement ability in human body. Composite material is preferred in the application because monolithic material does not meet the requirement. In this study, we have developed HAp/TCP composite. The mechanical property of the material is evaluated by the bending strength test. The bone replacement ability is evaluated by soaking the material in simulated body fluid (SBF). Measured result of concentration of Ca^<2+> ion in SBF indicated that the developed material has excellent bone replacement ability. The bending strength is maintained after I week of soaking in SBF due to precipitation of HAp on the surface proceeding to degrease of the strength at early stage of soaking due to dissolution of TCP.

Preparation of a Bioactive Poly(ε-Caprolactone) Triol/Silica Composite

Effect of poly(ε-caprolactone) structure on the mechanical properties and apatite-forming ability of poly(ε-caprolactone)/silica composite was investigated. Star-shaped poly(ε-caprolactone) was used in the experiment and it was end-capped with 3-isocyanopropyl triethoxysilane following the reaction with tetraethyl orthosilicate by sol-gel method. It was heat-treated at 150 oC for 24 hours and then tensile mechanical and dynamic viscoelastic testings were conducted, respectively. Its bioactivity was evaluated by the apatite forming ability in simulated body fluid at 36.5 oC. Its tensile strength was about 22 MPa while elastic modulus was about 2.6 GPa when the content of poly(ε-caprolactone) was 60 wt.%. The formation of apatite crystals on its surface was confirmed after 1 week of soaking in the SBF. The high elastic modulus of this composite was explained in terms of its 3-dimensional network structure.

Preparation of β-Tricalcium Phosphate Containing Silica by CO&lt;sub&gt;2&lt;/sub&gt;-Laser-Irradiation

Silicon is one of the essential ions with a stimulating effect on bone formation. β- tricalcium phosphate ceramic (β-TCP) with a modified surface containing silica was prepared in order to accelerate the bone formation. Sintered β-TCP pellets were spin-coated with a prehydrolyzed silica sol, and subsequently laser-irradiated using CO2 laser at the power of 6.5W. Scanning electron microscopy attached with X-ray energy dispersive spectrometry (SEM-EDS) showed that the silica was doped into the β-TCP surface. The silicon ion was released into a trisbuffer solution at pH 7.4 at 37 oC during one week of soaking.

Use of PLGA scaffold for mucociliary epithelium transfer in airway reconstruction: a preliminary study

Conclusion. A PLGA biodegradable membrane can be used as a scaffold for mucociliary epithelium transfer. Objectives. The aim of this study was to examine the usefulness of the PLGA membrane as a biodegradable scaffold for mucociliary epithelium transfer in order for it to be used as a substitute for a skin graft for restoring mucosal defects in the airway. Methods. A PLGA biodegradable membrane was synthesized using the immersion precipitation method, and morphologic characterization was carried out using scanning electron microscopy (SEM). The degradation test was performed by soaking the PLGA membrane in a culture medium, and the morphological changes were observed by SEM. Human nasal basal epithelial (HNBE) cells were cultured on the newly synthesized PLGA membrane, and the morphological changes were analyzed using SEM. The MUC5AC and MUC8 mRNA levels were analyzed by RT-PCR. Results. The PLGA membrane for the mucociliary epithelium transfer was successfully fabricated. It had a 24 mm diameter, a 50 µm thickness, and many pores with diameters of approximately 3 µm. The PLGA membrane began to degrade from 7 days after it was soaked in the culture medium. It rapidly degraded from 3 weeks and severe destruction of the pore structure was noted from 4 to 6 weeks of soaking. The HNBE cells were well differentiated into the mucociliary epithelium on the PLGA membrane both phenotypically and genotypically.

In vivo studies of polypyrrole/peptide coated neural probes

Neural probes are micromachined multichannel electrode arrays that facilitate the functional stimulation and recording of neurons in the peripheral and central nervous system. For long-term implantations, surface modification is necessary for maintaining the stable connection between electrodes and neurons. The conductive polymer polypyrrole (PPy) and synthetic peptide DCDPGYIGSR were co-deposited on the electrode surface by electrochemical polymerization. The stability of PPy/DCDPGYIGSR coatings was tested in soaking experiments. It was found that the peptide was entrapped in the PPy film and did not diffuse away within 7 weeks of soaking in DI water. Coated probes were implanted in guinea pig brain for periods of 1, 2 and 3 weeks. Recording tests were performed and the impedance was monitored. The explanted probes and tissue were examined by immunocytochemical studies. Significantly more neurofilament positive staining was found on the coated electrode which indicated that the coatings had established strong connections with the neuronal structure in vivo. Good recordings were obtained from the coated sites that had neurons attached. First week tissue sections had no significant gliosis. In week 2, a layer of non-neuronal tissue consisting of mostly meningeal fibroblasts and ECM protein including at least fibronectin was formed around the probe tracks of both coated and uncoated probes. Astrocytes started to form a loosely organized layer by the end of the third week.

Microstructural characterization and in vitro apatite formation in CaO–P2O5–TiO2–MgO–Na2O glass-ceramics

Abstract Bulk calcium phosphate glass and glass–ceramic with CaO/P 2 O 5 molar ratio=1.25 were prepared through introducing small amounts of Na 2 O, MgO, and TiO 2 into the glass. Using XRD analysis, biocompatible β-Ca 2 P 2 O 7 (β-DCP) and more soluble Ca and Na-containing phases were clearly identified in the microstructure. In vitro bioactivity was assessed by immersion testing in SBF-simulated body fluid and apatite crystals were formed after 4 and 8 weeks of soaking. Porous microstructure was produced through dissolution of soluble phases and desirable porous structure may be achieved by controlling size and distribution of these phases and the leaching process. Therefore, this glass–ceramic is expected to be used as bone repair and regeneration implants and drug delivery carrier.

Vapor Phase Reactions of Organoaminosilanes with Quartz

A technique for modifying the natural water-wetting behavior of polished quartz plates is discussed. The method involves chemical bonding of an organoaminosilane in the vapor phase to hydroxyl groups at the quartz surface. The dynamic Wilhelmy plate apparatus provided rapid and convenient evaluation of the silylation reactions. Three different silylation temperatures were investigated for both monofunctional hexamethyldisilazane (HMDS) and bifunctional bis(dimethylamino)dimethylsilane (BDMADMS). With both types of silane, only experiments at the highest temperature, 275°C, resulted in new siloxane bonds at the surface and, hence, strongly oil-wetting behavior. The persistence of the modified surfaces upon immersion of the plates in water varied considerably with the type of silane used. The surface of the HMDS-treated plates started to degrade within 24 h after soaking the plates in water. Plates treated with BDMADMS remained oil wetting in both directions of the wetting cycle for up to 13 weeks of soaking in water and at least 9 additional weeks when soaked in other liquids.