溶胶-凝胶法制备镁蔷薇辉石的体外生物活性研究

用溶胶-凝胶法制备出纯相镁蔷薇辉石(Ca3MgSi2O8)粉体,并在10MPa的轴向压力下,将其压制成尺寸为Ф10mm×5mm的圆柱状块体,通过模拟体液浸泡对其体外生物活性进行研究.用X射线衍射(XRD)及扫描电镜(SEM)分别对粉体以及浸泡后形成的羟基磷灰石(Hap)的物相和表面形貌进行表征.结果表明:在约1400℃的煅烧温度下可以得到纯相镁蔷薇辉石粉体,其粒径约为1～3μm;圆柱状镁蔷薇辉石在模拟体液浸泡7d后就能明显检测到表面有羟基磷灰石生成,浸泡14d后呈结晶较好的蠕虫状结构.因此,溶胶-凝胶法合成的镁蔷薇辉石具有良好的诱导羟基磷灰石形成能力和体外生物活性.     

含锶硼酸盐基生物玻璃经晶化处理后对其溶解性能及体外生物活性的影响

通过对含锶硼酸盐基玻璃进行微晶化处理,以考察该玻璃由玻璃态转化为晶态时体外生物活性和降解性的改变。采用熔融法制备不同锶含量(n(SrO)=0、2%、6%)的硼硅酸盐生物玻璃,然后在700℃/4h条件下微晶化处理,分别获得微晶化前后的试样。将各组玻璃及微晶化的样品浸泡在类似于生理模拟液的0.02mol/L的K2HPO4溶液中(以1g玻璃对应100mL浸泡液的比例),置于37℃恒温条件下,进行体外生物矿化反应。用XRD和FT-IR对反应后产物进行表征,并测定不同浸泡时间下样品的质量损失率以及浸泡液的pH值。结果表明,微晶化处理前后的含锶的硼硅酸盐玻璃试样在浸泡实验中都可以转化成含锶羟基磷灰石,即微晶化后的试样仍然具有体外生物活性;并且微晶化后试样的离子溶出速度能够减缓,降低了原玻璃相对骨组织生长来说的较高的降解速度,可以更加匹配骨组织生长的周期。因此,微晶化处理硼硅酸盐玻璃可实现对降解速度的调控,使该微晶化的生物玻璃有可能在骨组织修复中得到临床应用。     

生物玻璃的原位复合及其生物活性

以正硅酸乙酯(TEOS)、磷酸三乙酯(TEP)、四水硝酸钙为无机前驱体,采用溶胶凝胶法原位复合聚乙烯醇(PVA)制备钙磷硅生物玻璃,研究了工艺流程、无机相前驱体的水解时间及模板的使用等对生物玻璃性能的影响.结果表明,在生物玻璃的原位复合中PVA模板与钙磷硅前驱体混合的工艺顺序不同,则样品的韧性不同.600℃热处理去除有机模板得到的生物的玻璃粉体表现出较高的比表面积和较大的中孔体积,在体外生理模拟液中浸泡7 d后矿化形成的活性碳酸钙与羟基磷灰石(HAP)微晶具有较高的生物活性.     

玻璃基生物骨水泥内部纳米羟基磷灰石的形成研究

以CaO-SiO2-P2O5系统生物玻璃和磷酸铵调和液混合制得玻璃基生物骨水泥(GBC),利用XRD、FTIR和SEM对GBC的产物晶相、化学组成和内部显微结构进行了分析,并对其力学性能进行了测试。实验结果表明,随着浸泡时间的增加GBC中的玻璃相逐步向羟基磷灰石(HAP)微晶转化,生成的磷灰石为弱结晶度的类骨状碳酸羟基磷灰石微晶,这些微晶主要分布于玻璃粉末的界面之间,端面尺寸在30～50nm,这表明GBC中所生成的HAY晶体与人体骨有很大的相似性,因而会具有良好的生物活性。对力学性能测试的结果表明,随着浸泡时间的增加GBC的抗压强度逐步增加,在30天时可达到80MPa。因而GBC不仅具有良好的生物活性,而且具有一定的力学强度。     

SPS烧结制备生物活性镁黄长石陶瓷

钙硅基生物陶瓷具有良好的生物活性和细胞相容性, 在生物医疗领域具有广阔的发展前景。但是其粉体烧结性能差的缺点导致很难获得致密的陶瓷材料, 阻碍了其应用的进程。本研究采用化学共沉淀法制备了纯度高且烧结活性好的镁黄长石粉体, 然后采用放电等离子烧结技术(SPS)制备了镁黄长石陶瓷材料。通过X射线衍射(XRD)和扫描电子显微镜(SEM)表征了样品的组成结构和显微形貌, 并通过阿基米德法和模拟体液浸泡法分析了镁黄长石陶瓷样品的致密度和生物活性。研究结果表明, 采用SPS技术在1170℃、70 MPa保温5 min条件下可获得致密度超过99%的镁黄长石陶瓷材料。在模拟体液中浸泡3 d, 陶瓷样品表面出现磷酸盐的沉积, 浸泡7 d后生成了类骨羟基磷灰石, 说明SPS技术制备的致密镁黄长石生物陶瓷具有良好的诱导沉积类骨磷灰石能力。     

溶胶-凝胶法在多孔钛表面制备二氧化钛生物涂层

室温下利用溶胶-凝胶法在多孔钛表面制备TiO2薄膜,并分别于不同温度热处理.利用电化学工作站测试不同温度煅烧后的TiO2薄膜在0.9%NaCl生理盐水中的耐腐蚀特性;利用XRD、SEM测试技术研究样品在模拟体液(SBF)内浸泡不同时间后的生物活性和显微结构.结果表明,600℃退火的TiO2薄膜的生物活性最强,只在SBF中浸泡10天就形成表面致密的磷灰石涂层,并且涂层的结晶细小而薄,没有破坏多孔钛的孔隙结构;800℃退火的TiO2薄膜因其最为致密,在生理盐水中的耐腐蚀性最好.     

电泳沉积制备羟基磷灰石/生物玻璃梯度涂层的研究

本文研究了羟基磷灰石颗粒、生物玻璃颗粒在醋酸介质中的电泳沉积规律 ,利用它们不同的沉积规律设计了羟基磷灰石 /生物玻璃梯度沉积装置。用电子探针分析了涂层横截面元素分布 ,表明所设计的装置可实现羟基磷灰石和生物玻璃的梯度涂层     

羟基磷灰石涂层材料的制备及其性能表征

设计并采用类似搪瓷涂覆的工艺制备了羟基磷灰石－Ｔｉ６Ａｌ４Ｖ复合材料．使用ＸＲＤ、ＳＥＭ对复合材料的相组成和显微结构进行分析和表征,在模拟体液中观察了获得材料的生物相容性．结果表明;在涂层中,羟基磷灰石粒子均匀地分散在玻璃基体中,它们保持原有的晶格结构,未发生相分解等现象．烧成温度对中间层玻璃涂层的显微结构有着较为明显的影响．中间层玻璃涂层与钛合金的结合强度或不小于２９．７３ＭＰａ,远高于等离子喷涂,达到使用要求．在模拟体液中浸泡一段时间后,ＸＰＳ分析表明复合材料表面有新生羟基磷灰石粒子析出,表明复合涂层有优良的生物相容性．     

电泳沉积制备羟基磷灰石／生物玻璃梯度涂层的研究

本文研究了羟基磷灰石颗料，生物玻璃颗粒在醋酸介质中的电泳沉积规律，利用它们不同的沉积规律设计了羟基磷灰石／生物玻璃梯度沉积装置，用电子探针分析了涂层横截面元素分布，表明所设计的装置可实现羟基磷灰石和生物玻璃的梯度涂层。     

生物玻璃涂层性能的研究

本实验所用涂层为磷硅酸盐玻璃系统,涂层以Sol-gel工艺制得.对该工艺制得的涂层于不同温度(700℃、800℃、900℃)下烧成后的各项性能进行比较,对涂层断面进行分析,以确定不同烧成温度下涂层-基体的界面状态.结果表明800℃烧成的涂层具有最好的综合性能:晶型简单;表面虽有裂纹存在,但基体并未裸露,实现了有效涂层的目的;层间扩散明显,涂层-基体界面处有良好过渡;与基体的结合强度高(2层为10.50MPa,4层为7.11MPa);在模拟体液(SBF)中浸泡30天后表面有大量羟基磷灰石(HA)生成,表明其具有良好的生物活性.     

Hydroxyapatite/Bioactive Glass Films Produced by a Sol–Gel Method: In Vitro Behavior

Hydroxyapatite (HA) and HA/bioactive glass (49S) films were deposited on Si(100) substrates by a sol–gel dip‐coating method. The microstructure and in vitro bioactivity of the films were investigated by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X‐ray photoelectron spectroscopy (XPS). Polycrystalline HA and amorphous bioactive glass films were obtained after annealing at 600 and 400 °C, respectively. The crystallization temperature of HA was determined to be around 568 °C. The surfaces of the HA films were covered with an apatite layer consists of spherulites formed by nanosized needle‐like aggregates after the soaking in simulated body fluid (SBF) for 10 days, while amorphous HA/bioactive glass surface was covered with larger spherical crystallites. Both XPS and EDS results obtained from HA/bioactive glass film, after soaking in SBF, showed increasing P amounts on the surface at the expense of Si. The higher density of the newly formed layer on HA/bioactive glass surface than that of the HA surface after 10 days of soaking was evidence of increased reaction rate and apatite forming ability when bioactive glass layer is present on the HA films.     

Fabrication and corrosion behavior of HA/Mg-Zn biocomposites

The thermal-treated hydroxyapatite (HA) particles, Mg and Zn powders were used to prepare the HA/Mg-Zn composites with different HA contents by means of powder metallurgy technology. The microstructures, formation phases, and corrosion behaviors in simulated body fluid (SBF) were studied in comparison with pure magnesium and HA/Mg composites fabricated by the same preparation technology. As a result, no evident reaction happened between HA particles and Mg matrix during sintering process, and Zn atoms diffused into Mg matrix to form a single phase Mg-Zn alloy matrix. The addition of HA particles changed the corrosion mechanism of Mg matrix. During the corrosion process, HA particles would adsorb and Ca²⁺ ions efficiently and induce the deposition of Ca-P compounds on the surface of composites. HA could improve the corrosion resistance of magnesium matrix composites in SBF and restrain the increase of pH of SBF. Furthermore, the addition of Zn was favorable to improve the corrosion resistance of HA/Mg composites due to the densification of composites and the formation of Mg-Zn alloy matrix.     

溶胶-凝胶生物活性玻璃纤维的制备及其体外矿化性能研究

采用溶胶-凝胶法制备出CaO-P2O5-SiO2系统生物活性玻璃纤维．通过倒置相差显微镜、SEM、FTIR等测试手段考察了生物活性玻璃纤维的微观形貌和显微结构；采用生物材料的体外实验方法以及XRD、SEM、FTIR等测试手段研究了生物活性玻璃纤维在模拟生理体液（SBF）中浸泡后的表面反应产物的形成机理、结晶程度和微观形貌．结果表明，这种生物活性玻璃纤维是一种不连续的短纤维，具有较好的纤维形态和较高的生物活性，在短时间内即可在模拟生理体液（SBF）中形成茸毛状A类碳酸羟基磷灰石（HCA）层．     

Gallium-containing phospho‐silicate glasses: Synthesis and in vitro bioactivity

A series of Ga-containing phospho-silicate glasses based on Bioglass 45S5, having molar formula 46.2SiO₂·24.3Na₂O·26.9CaO·2.6P₂O₅·xGa₂O₃ (x = 1.0, 1.6, 3.5), were prepared by fusion method. The reference Bioglass 45S5 without gallium was also prepared. The synthesized glasses were immersed in simulated body fluid (SBF) for 30 days in order to observe ion release and hydroxyapatite (HA) formation. All Ga-containing glasses maintain the ability of HA formation as indicated by main X-ray diffractometric peaks and/or electronic scanning microscopy results. HA layer was formed after 1 day of SBF soaking in 45S5 glass containing up to 1.6% Ga₂O₃ content. Moreover, gallium released by the glasses was found to be partially precipitated on the glass surface as gallium phosphate. Further increase in gallium content reduced the ion release in SBF. The maximum of Ga³⁺ concentration measured in solution is ~ 6 ppm determined for 3.5% Ga₂O₃ content. This amount is about half of the toxic level (14 ppm) of gallium and the glasses release gallium till 30 days of immersion in SBF. Considering the above results, the studied materials can be proposed as bioactive glasses with additional antimicrobial effect of gallium having no toxic outcome.     

Biomimetic apatite formation on a CoCrMo alloy by using wollastonite,bioactive glass or hydroxyapatite

A biomimetic method was used to promote a bioactive surface on a CoCrMo alloy (ASTM F75). To enhance the nucleation of apatite on the metallic substrate, wollastonite ceramics (W), bioactive glass (BG) or hydroxyapatite (HA) were used in the biomimetic method. Metallic samples were chemically treated and immersed for 7 days in SBF on a bed of bioactive material (W, BG or HA) followed by an immersion in 1.5SBF for 7 or 14 days without bioactive system.A bonelike apatite layer was formed on the surface of all the samples tested. The samples treated with wollastonite showed a higher rate of apatite formation and the morphology of the layer was closer to that of the existing bioactive systems. A higher crystallinity of the apatite layer was also observed by using wollastonite. The pH of the SBF, the Ca/P ratio and the thickness of the layer on the samples treated with wollastonite and bioactive glass increased as increasing the immersion time. The thickness of the layer on the samples treated with hydroxyapatite also increased with time, but the pH of the SBF and the Ca/P ratio changed with no a defined trend.     

MAS-NMR support for Hench model in the case of bioactive glass microspheres

The structural changes occurred in bioactive glass microspheres belonging to the system SiO₂–Na₂O–P₂O₅–CaO–K₂O–MgO incorporating yttrium were investigated before and after soaking in simulated body fluid (SBF) by X-ray diffraction (XRD) and ³¹P and ²⁹Si magic angle sample spinning nuclear magnetic resonance (MAS-NMR). The addition of yttrium to the bioactive glass composition induces changes in the behavior of the glass microspheres in SBF. The XRD analysis proves that after the immersion in SBF a crystalline hydroxyapatite-like phase is developed on the microspheres surface. The ²⁹Si and ³¹P MAS-NMR results show that silicate species with two and three bridging oxygens per SiO₄ tetrahedra and PO₄ monomeric units are present in the glass structure. After immersion in SBF, new silicate species with four bridging oxygens appear as result of silica-gel layer formed on microspheres surface. The formation of crystalline hydroxyapatite-type layer is reflected by the occurrence of narrow components in ³¹P MAS-NMR spectra. The NMR results support the Hench model for bioactive glasses behavior in biological environments.     

Characterisation of the bioactive behaviour of sol–gel hydroxyapatite–CaO and hydroxyapatite–CaO–bioactive glass composites

The fabrication and characterization of sol–gel derived hydroxyapatite–calcium oxide (HAp–CaO) material is investigated focusing on the effect of the addition of a bioactive glass on the material bioactive behaviour through the fabrication of a novel HAp–CaO (70 wt.%)–bioactive glass (30 wt.%) composite material. The bioactive behaviour of the materials was assessed by immersion studies in Simulated Body Fluid (SBF) and the alterations of the materials surfaces after soaking periods in SBF were characterized by Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR). A brittle and weakly crystalline carbonate hydroxyapatite (HCAp) layer was found to develop on the surface of all samples, few hours after immersion in SBF, confirming the high bioactivity of the material. Alterations of the morphology of the developed HCAp layer, which led to a more compact structure, were observed on the surface of composite samples after 7 days of immersion in SBF. The presence of the CaO phase seems to accelerate the formation of HCAp, while the bioactive glass affects both the morphology and cohesion of the developed layer.     

Microwave energy-assisted formation of bioactive CaO–MgO–SiO<Subscript>2</Subscript> ternary glass from bio-wastes

Regeneration technique is extensively being sought after as a means of achieving bone repair without adverse immunological response. Silicate-based bioactive glasses containing Mg are gaining increasing attention for their biocompatibility. The current work has been focused on designing a facile and economic route using bio-wastes for synthesizing bioactive glasses in the CaO–MgO–SiO₂ system. Rice husk ash (RHA) obtained from burning rice husk was used as silica source, while Ca was extracted from eggshells for preparing the glass through a modified sol–gel approach. The gel formed was irradiated in microwave before sintering at 950^°C for 3 h. Thereafter, bioactivity test was conducted on the samples in simulated body fluid (SBF) at physiological conditions for a maximum of 14 days. Characterization of samples were performed before and after immersion in SBF to evaluate the composition, morphology and phases present in the glass using energy-dispersive X-ray analysis, scanning electron microscopy and X-ray diffraction. Apatite formation was confirmed using Fourier transform infrared spectroscopy. Results obtained showed the presence of diopside, wollastonite and pseudo-wollastonite as major bioactive phases. Hydroxyapatite formed on the material within 3 days in SBF, indicating good bioactivity.     

Synthesis,bioactivity and preliminary biocompatibility studies of glasses in the system CaO–MgO–SiO<Subscript>2</Subscript>–Na<Subscript>2</Subscript>O–P<Subscript>2</Subscript>O<Subscript>5</Subscript>–CaF<Subscript>2</Subscript>

New compositions of bioactive glasses are proposed in the CaO–MgO–SiO₂–Na₂O–P₂O₅–CaF₂ system. Mineralization tests with immersion of the investigated glasses in simulated body fluid (SBF) at 37°C showed that the glasses favour the surface formation of hydroxyapatite (HA) from the early stages of the experiments. In the case of daily renewable SBF, monetite (CaHPO₄) formation competed with the formation of HA. The influence of structural features of the glasses on their mineralization (bioactivity) performance is discussed. Preliminary in vitro experiments with osteoblasts’ cell-cultures showed that the glasses are biocompatible and there is no evidence of toxicity. Sintering and devitrification studies of glass powder compacts were also performed. Glass-ceramics with attractive properties were obtained after heat treatment of the glasses at relatively low temperatures (up to 850°C).     

Fabrication and corrosion behavior of HA/Mg-Zn biocomposites

The thermal-treated hydroxyapatite (HA) particles, Mg and Zn powders were used to prepare the HA/Mg-Zn composites with different HA contents by means of powder metallurgy technology. The microstructures, formation phases, and corrosion behaviors in simulated body fluid (SBF) were studied in comparison with pure magnesium and HA/Mg composites fabricated by the same preparation technology. As a result, no evident reaction happened between HA particles and Mg matrix during sintering process, and Zn atoms diffused into Mg matrix to form a single phase Mg-Zn alloy matrix. The addition of HA particles changed the corrosion mechanism of Mg matrix. During the corrosion process, HA particles would adsorb PO₄³⁻ and Ca²⁺ ions efficiently and induce the deposition of Ca-P compounds on the surface of composites. HA could improve the corrosion resistance of magnesium matrix composites in SBF and restrain the increase of pH of SBF. Furthermore, the addition of Zn was favorable to improve the corrosion resistance of HA/Mg composites due to the densification of composites and the formation of Mg-Zn alloy matrix.