Microstructure and Chemical States of Hydroxyapatite/silk Fibroin Nanocomposites Synthesized via A Wet-mechanochemical Route

Hydroxyapaptite (HAp)/silk fibroin (SF) nanocomposites were prepared via a wet-mechanochemical route at room temperature. The results reveal that the inorganic phase in the composites is carbonate-substituted HAp containing 2.9–3.1 wt% of carbonate ions. The primary HAp crystals are rod-like in shape with a typical size of 20–30nm in length and 8–10nm in width, and lattice parameters a = 9.423, c = 6.888. The self-assembled HAp crystals along their c-axes aggregate into bundles, which are connected with SF fibrils. Consequently, a three-dimensional porous network is formed in the composite, which is beneficial to inducing new bone formation in practical implantation.     

电沉积HA/TiO2复合涂层的结合强度和热稳定性研究

HA/TiO₂ composite coating were fabricated via adding TiO₂ powder in the electrolyte by electrodeposition. The influence of current density and deposition time on the content of TiO₂ in the coating, the influence of the content of TiO₂ in the coating on the bonding strength of coating and the influence of sintering temperature on the structure and the bonding strength of coating were investigated. The experiment results show that the content of TiO₂ in the coating increase with reducing the current density and prolonging the deposition time, the bonding strength improve with increasing the content of TiO₂ in the coating, which can obtain 18.7 MPa when the weight percent TiO₂ in the coating attain 72.2 %. The addition of TiO₂ in the coating reduces the thermal expansion coefficient of the coating, improves the bonding strength of coating and changes the fracture mechanism of the coating from adhesion failure to cohesive failure. HA in the composite coatings is decomposed by the catalysis reaction of TiO₂ at the temperature of sinter 850 ℃. Differential scanning calorimetry and X-ray diffractometry analyses showed that the chemical reaction between HA and TiO₂ lead to the product are α-TCP and CaTiO₃ at the temperature of sinter 1200 ℃. In order to prevent the coating from decomposing and attain hign bonding strength, the sintering temperature should be less than 820 ℃.     

Fourier Transform and Multi Dimensional EPR Spectroscopy for the Characterization of Hydroxyapatite Gels

Calcium hydroxyapatite powder was prepared by the sol-gel method, using calcium acetate and PO(OC₂H₅)₃ as initialcompounds, and alcohol(methyl, ethyl, and propyl-alcohol) as solvent. Homogenous solutions andgels were prepared, using a molar ratio of Ca / P = 1.67. Theevolution of the structure was followed by XRD (X-ray diffraction), IR(Infrared), and FT-n(= 1, 2, 3)D-EPR (Fourier transform Electron Paramagnetic Resonance) spectroscopy. The dried gel exhibits a signalcharacterized by a central line and two satellites. The 2D spectrum(Electron Spin Echo Envelop Modulation ESEEM vs. field sweep) showed thesame modulation for the central line. The FT-EPR spectrum vs. field sweep2D-spectrum indicated that the satellites are due to an hfs splitting withwater. The central region of this 2D spectrum is influenced by P and H in a concentration ratio of[H] / [P] = 2.5. TheESEEM spectrum was simulated, assuming the equation for two spin systems S = 1/2 andI = 1/2. This simulation gave, for m and n, the values of 2 and5, respectively. This finding suggests a–P–O–P–O–P– linear evolution of thestructure. It appears that one ethyl group does not hydrolyze in thegelation process. This result was confirmed by IRspectroscopy.     

水热电沉积羟基磷灰石/Ti复合涂层的研究

在水热电沉积羟基磷灰石（Hydroxyapatite，简称HA）涂层的电解液中加入Ti粉，制备了HA/Ti复合涂层，探讨了Ti粉的加入对涂层结合强度和生物活性的影响，并研究了涂层的热稳定性。结果表明，500 ℃焙烧2 h后，HA/Ti复合涂层的结合强度为18.4 MPa，明显高于纯HA涂层的11.2 MPa；模拟体液浸泡7 d后，涂层表层形成一层碳磷灰石。Ti粉的加入明显提高了涂层的结合强度，又不降低涂层的生物活性。500 ℃焙烧不改变涂层的相组成，焙烧温度高于600 ℃时，HA部分发生分解，Ti氧化为金     

Anti-Microbial Hydroxyapatite Particles Synthesized by a Sol–Gel Route

Sol–gel route was applied to synthesize anti-microbial hydroxyapatite (HAp) powders by the addition of silver 200–20000 ppm or zinc salts. The bacteria strain, Streptococcus mutans (S. mutans, ATCC 25175) was used in the anti-bacterial tests. HAp phase was reproducibly obtained by the preparation conditions: Ca(NO₃)₂-4H₂O and trietheyl phosphate as sources of calcium and phosphorus sources, respectively, and ethanol as the solvent, aging for 16 h at 80°C, gelation and drying at 80°C for 24 h, then calcining at above 350°C. TGA was used to analyze thermal properties of the as-prepared gel. XRD and FTIR were used to identify the crystalline phase and chemical structure. CaO appeared as an impurity after calcining above 650°C. In the solid-state anti-microbial tests on the brain heart infusion (BHI) agar plates, there formed a microbial inhibition zone surrounding the Ag/Zn added (greater than 2000 ppm) samples. In the liquid-state anti-microbial tests, S. mutans cells readily precipitated with pure HAp powders but not with Ag/Zn added (greater than 2000 ppm) HAp powders. The concentration of silver or zinc ions releasing from the Ag/Zn added HAp powders into the supernatant of the BHI broth was under detection limit of ICP-AES analyses. However, the growth of S. mutans reached same magnitude (6 × 10⁸ CFU/mL) whether pure HAp, 2000 ppm-Ag or 2000 ppm-Zn were added. Therefore, Ag/Zn added HAp powders developed in this research present microbial inhibition properties and are of potential as a solid-state anti-microbial agent.     

介孔生物活性玻璃材料在模拟体液中的用量对考察其体外生物活性的影响

制备了具有骨修复性能的新型介孔生物玻璃(mesoporous bioactive glass, MBG)材料. 在其它条件相同时改变MBG在模拟生理体液(simulated body fluid, SBF)中的用量比(0.0001～0.002 g/mL), 考察了材料的体外生物活性. 用等离子体原子发射光谱测定了不同反应时间SBF中钙、磷、硅物种的浓度; 用傅立叶红外光谱和电子扫描显微镜对材料进行了表征. 结果表明: MBG材料表面羟基磷灰石的形成速度和材料在SBF中的用量比直接相关, 其中用量比在0.001 g/mL时表现出最佳的体外生物活性. 最佳用量比的确定, 对于深入理解MBG材料的结构与体外活性的关联, 筛选具有更佳生物活性的MBG材料有着重要的意义.     

Effect of the type of nanoaddition on the thermal properties of polyacrylonitrile fibres

Thermal properties of precursor polyacrylonitrile fibres containing nanoparticles of additives such as SiO₂, hydroxyapatite and montmorillonite have been examined. The thermal curves of the fibres under investigation obtained by the derivatographic method in air and DSC in a neutral gas atmosphere were interpreted from the point of view of physical and chemical changes in the fibre-forming polymer. Based on the thermogravimetric curves, the coefficients of thermal stability of the fibres were found. It has been found that the thermal stability of PAN fibres is affected by the type of nanoadditives and the value of the as-spun draw out ratio used during fibre spinning.     

Calcium hydroxyapatite solubilisation in the hydrochloric and perchloric acids

Summary Enthalpy of solution of calcium hydroxyapatite Ca₁₀(PO₄)₆(OH)₂ (CaHap) in hydrochloric and perchloric acid solutions is measured by an isoperibol calorimeter and a C80 microcalorimeter. The former device is adapted to reactions occurring in concentrated acid solutions, whereas the microcalorimeter is suitable for slow processes happening in diluted acid solutions. Some solution mechanisms are suggested for different pH ranges. They are confirmed by complementary solution in the same solvent of the entities produced by the reaction between CaHap and the acid. These entities are CaCl₂; Ca(ClO₄)₂·nH₂O; Ca(H₂PO₄)₂ and H₃PO₄. Extrapolation of solution enthalpies to pH=7 leads to the solution enthalpy of (CaHap) in pure water, which is -406.2 kJ mol^-1 from HCl and -437.3 kJ mol^-1 from HClO₄.     

Apatite-Silica Gel Composite Materials Prepared by a New Alternate Soaking Process

Novel apatite/silica composite materials were synthesized by modifying the surface of silica gel beads or plates with apatite. An alternate soaking process, which involves alternate soaking in a CaCl₂/tris-HCl aqueous solution (pH 7.4) and a Na₂HPO₄ aqueous solution, was utilized to prepare a composite of silica gel and apatite. The characteristics of apatite formed on the surface of silica gel have been studied using X-ray diffraction, Fourier-transform infrared spectrophotometry (FT-IR) and scanning electron microscopy (SEM). Data clearly showed surface modification of silica with the crystalline apatite. Pore volume and specific total surface area, which were measured using nitrogen gas adsorption apparatus, were decreased after apatite deposition on the surface of silica gel beads, whereas the external surface area was increased drastically. The alternate soaking process made it possible to prepare apatite/silica gel composites in a remarkably short period of time, i.e. several hours.     

纳米结构羟基磷灰石的微波固相合成新方法

本文报道了一种简单的室温下微波辅助合成羟基磷灰石(HAP)的新方法。与常规方法相比，该方法具有反应条件温和、反应时间极短的优点。合成中，以Ca(NO₃)₂·4H₂O和Na₃PO₄·12H₂O为原料，经过研磨和微波加热得到了HAP纳米粒子和纳米棒。用XRD、FTIR，BET和SEM等对产物进行了表征。在反应过程中，微波辐射作为一种加热处理手段对HAP的形成起到非常重要作用。同时