Biomimetic Porous Bone-Like Apatite Coatings on Metals, Organic Polymers and Microparticles

When pH and temperature of simulated body fluid (SBF) are raised, fine particles of calcium phosphate are precipitated. Recently, the authors’ research group found that these fine particles were highly active to induce formation of porous bone-like apatite in SBF, or body fluid, and named them ‘apatite nuclei.’ By using apatite nuclei, the author successfully imparted high bioactivity, that is, apatite-forming ability, to various kinds of bioinert biomaterials such as metals and organic polymers in a series of recent studies. These materials spontaneously formed porous bone-like apatite layer on their surfaces in SBF in a short time and showed high bioactivity in vitro. In addition, thWe author also successfully fabricated microcapsules consisted of porous bone-like apatite by using apatite nuclei

Biomimetic Fabrication of Hydroxyapatite Microcapsules by Using Apatite Nuclei

Edited by Amitava Mukherje

Electrochemical Properties of Cs and La Co-doped CaWO₄ Oxide Ion Conductor

To clarify the contribution of defect structure of CaWO₄-based system on the oxide ion conduction properties, we doped both cesium and lanthanum ions into CaWO₄ as Ca₀.₉CsxLa₀.₁−xWO₄.₀₅−x. Scheelite-type structured solid solution can be obtained for the Cs-rich region (x ≥ 0.05) with oxygen deficiency, while second phase appears for La-rich region (x ≤ 0.025) assuming excess oxide ions. In the present system, a bend in Arrhenius plot of conductivity is observed around 850 °C as the typical CaWO₄-based system even co-doping with La ions. In terms of the compositional dependence, ionic conduction develops from x = 0.05 with the amount of cation vacancy below 800 °C, while the conductivity enhancement starts at the La-rich region above 900 °C. This indicates that not only oxide ion vacancy but also interstitial attribute to the oxide ion conduction at high-temperature, which is also suggested by the activation energy

Synergistic effect of sulfonation followed by precipitation of amorphous calcium phosphate on the bone-bonding strength of carbon fiber reinforced polyetheretherketone

Sulfonation and applications of amorphous calcium phosphate are known to make polyetheretherketone (PEEK) bioactive. Sulfonation followed by precipitation of amorphous calcium phosphate (AN-treatment) may provide PEEK with further bone-bonding strength. Herein, we prepared a carbon-fiber-reinforced PEEK (CPEEK) with similar tensile strength to cortical bone and a CPEEK subjected to AN-treatment (CPEEK-AN). The effect of AN-treatment on the bone-bonding strength generated at the interface between the rabbit’s tibia and a base material was investigated using a detaching test at two time-points (4 and 8 weeks). At 4 weeks, the strength of CPEEK-AN was significantly higher than that of CPEEK due to the direct bonding between the interfaces. Between 4 and 8 weeks, the different bone forming processes showed that, with CPEEK-AN, bone consolidation was achieved, thus improving bone-bonding strength. In contrast, with CPEEK, a new bone was absorbed mainly on the interface, leading to poor strength. These observations were supported by an in vitro study, which showed that pre-osteoblast on CPEEK-AN caused earlier maturation and mineralization of the extracellular matrix than on CPEEK. Consequently, AN-treatment, comprising a combination of two efficient treatments, generated a synergetic effect on the bonding strength of CPEEK

Impartation of hydroxyapatite formation ability to ultra-high molecular weight polyethylene by deposition of apatite nuclei

Special Section: Selected Extended Papers from the International Conference of the 19th Asian BioCeramic SymposiumThe authors aimed to impart hydroxyapatite formation ability to ultra-high molecular weight polyethylene (UHMWPE) by deposition of apatite nuclei (ApN) by the following two methods. The first method was electrophoretic deposition (EPD). A porous UHMWPE was placed between electrodes in the ApN-dispersed ethanol and constant voltage was applied. By this treatment, the ApN were migrated from anode-side surface to the cathode one through the pores by an electric field in the pores of the UHMWPE and deposited inside the pores. The second method was direct precipitation (DP) of the ApN. A porous UHMWPE was soaked in a simulated body fluid (1.0SBF) with higher pH than the physiological one and subsequently, its temperature was raised. By this treatment, the ApN were precipitated in the pores of the UHMWPE directly in the reaction solution. For both methods, the ApN-deposited UHMWPE showed HAp formation ability not only on the top surface but also inside the pores near the surface of the porous UHMWPE in 1.0SBF although the adhesion strength of thus-formed HAp layer was higher in the case of the EPD in comparison with the DP, oxygen plasma treatment before the DP enabled to achieve a similar level of the HAp layer adhesion to the EPD

Bioactivity Treatment to Polylactic Acid Fabric Cloth and Foam by Precipitation of Apatite Nuclei

An aqueous solution with doubled ion concentration of simulated body fluid (2.0SBF) was prepared. In order to impart hydroxyapatite formation ability to polylactic acid (PLA) matrixes, the PLA fabric cloth and foam were immersed in 2.0SBF and the pH value was increased. By this treatment, apatite nuclei were precipitated on the PLA matrixes. By immersing in physiological SBF, hydroxyapatite layer was formed on the surface of the PLA matrixes and hydroxyapatite formation ability was successfully performed

INVESTIGATION OF EFFECTIVE PROCEDURES IN FABRICATION OF BIOACTIVE PEEK USING THE FUNCTION OF APATITE NUCLEI

We made micropores on the surface of a polyether ether ketone (PEEK) by immersing in sulfuric acid. In order to provide bioactivity to PEEK, we treated the surfaces of the specimens with glow-discharge in O2 gas atmosphere and precipitated Apatite Nucleus (AN) in the micropores. We evaluated apatite-forming ability of the specimens by using SBF and measured adhesive strength of formed apatite layer. In this study, we researched which treatment is effective to give bioactivity to PEEK

アパタイト カク キノウ ニ ヨル セイタイ カンキョウ テキゴウ ザイリョウ ノ カイハツ

京都大学0048新制・課程博士博士(エネルギー科学)甲第14962号エネ博第205号新制||エネ||46(附属図書館)27400UT51-2009-M876京都大学大学院エネルギー科学研究科エネルギー基礎科学専攻(主査)教授 八尾 健, 教授 尾形 幸生, 教授 森井 孝学位規則第4条第1項該当Doctor of Energy ScienceKyoto UniversityDA

Development of Apatite Nuclei Precipitated Carbon Nanotube-Polyether Ether Ketone Composite with Biological and Electrical Properties

We aimed to impart apatite-forming ability to carbon nanotube (CNT)-polyether ether ketone (PEEK) composite (CNT-PEEK). Since CNT possesses electrical conductivity, CNT-PEEK can be expected to useful not only for implant materials but also biosensing devices. First of all, in this study, CNT-PEEK was treated with sulfuric acid to form fine pores on its surface. Then, the hydrophilicity of the substrate was improved by oxygen plasma treatment. After that, the substrate was promptly immersed in simulated body fluid (SBF) which was adjusted at pH 8.40, 25.0 °C (alkaline SBF) and held in an incubator set at 70.0 °C for 1 day to deposit fine particles of amorphous calcium phosphate, which we refer to as ‘apatite nuclei’. When thus-treated CNT-PEEK was immersed in SBF, its surface was spontaneously covered with hydroxyapatite within 1 day by apatite nuclei deposited in the fine pores and high apatite-forming ability was successfully demonstrated. The CNT-PEEK also showed conductivity even after the above treatment and showed smaller impedance than that of the untreated CNT-PEEK substrate

Fabrication of Bioactive Co-Cr-Mo-W Alloy by Using Doubled Sandblasting Process and Apatite Nuclei Treatment

Roughened surface was formed on the surface of Co-Cr-Mo-W alloy substrate by applying doubled sandblasting method using silicon carbide grinding particles with 14 μm and subsequently 8 μm in average diameter. In order to impart hydroxyapatite formation ability to the Co-Cr-Mo-W alloy, the substrate was immersed in simulated body fluid (SBF) with ion concentrations nearly equal to those of human blood plasma adjusted at higher pH in comparison with those of physiological SBF and heated. By this treatment, apatite nuclei were formed on the Co-Cr-Mo-W alloy. By immersion in physiological SBF, hydroxyapatite covered whole surface of the substrate within 3 days and high hydroxyapatite formation ability was performed. The formed hydroxyapatite layer was adhered by mechanical interlocking effect between the substrate with roughened surface and the hydroxyapatite layer