磁性生物活性陶瓷的制备

采用溶胶-凝胶法制备前驱体,经高温烧结制备出磁性生物活性陶瓷。利用体外实验方法,结合X射线衍射、扫描电子显微镜和红外光谱分析了材料结构、晶相和生物活性。结果显示,溶胶-凝胶法可制备出微细的非晶态前驱体粉末,经1 050℃烧结的玻璃陶瓷主晶相为β-硅灰石和铁酸钴、磷硅灰石。陶瓷粉末平均粒径为300 nm。烧结的材料在模拟人体血浆浓度的模拟体液中浸泡7 d,在材料表面可生成大量磷灰石,显示出较好的生物活性。     

溶胶-凝胶法与两步沉淀法制备的镁黄长石粉体的体外生物活性比较

通过溶胶-凝胶法和两步沉淀法分别合成镁黄长石(Ca2MgSi2O7)粉体,并通过模拟体液浸泡对这两种方法合成的镁黄长石的体外生物活性进行比较。用X射线衍射、扫描电镜、原子发射光谱(ICP-AES)以及pH计分别对浸泡后形成的羟基磷灰石的物相、形貌以及浸泡后模拟体液的离子浓度变化、pH值进行表征。结果表明：两步沉淀法合成的镁黄长石在浸泡5d后就能明显检测到羟基磷灰石生成,而溶胶-凝胶法合成的镁黄长石在浸泡7d后才能检测到羟基磷灰石生成;两步沉淀法合成的镁黄长石诱导的羟基磷灰石呈结晶较好的虫状结构,而溶胶-凝胶法合成的镁黄长石诱导的羟基磷灰石呈结晶不完整的圆形颗粒结构;而且,两步沉淀法合成的镁黄长石具有更快的Ca离子释放能力。因此,两步沉淀法合成的镁黄长石相对于溶胶-凝胶法合成的镁黄长石具有更好的诱导羟基磷灰石形成能力和生物活性。     

生物活性β-硅酸二钙的喷雾干燥-微波快速烧结制备与性能表征

将微波烧结工艺与喷雾干燥技术相结合,成功探索了一种制备β-Ca2SiO4陶瓷的新工艺,考察了制备的β-Ca2SiO4陶瓷的生物活性。用扫描电子显微镜、X射线衍射和红外光谱分析对前驱体和β-Ca2SiO4陶瓷进行了表征。结果表明:前驱体为四水硝酸钙、硝酸钙及硅溶胶的混合物,由80～300nm的粒子团聚而成;新工艺制备的β-Ca2SiO4陶瓷可在30min内于900℃烧成,并且不发生β→γ的相变。通过模拟体液浸泡实验考察了制备的β-Ca2SiO4陶瓷的生物活性,结果表明:制备的β-Ca2SiO4陶瓷,通过模拟体液浸泡可在72h内诱导类骨磷灰石沉积在表面,显示出良好的生物活性。由此得出结论:采用喷雾干燥-微波烧结工艺制备β-Ca2SiO4陶瓷,与传统工艺相比,能显著降低烧结温度,缩短烧结所需时间,并且制备的β-Ca2SiO4陶瓷具有良好的生物活性。     

热压烧结制备硅酸钙生物陶瓷的工艺与生物活性研究

以分析纯的四水硝酸钙(Ca NO3·4H2O)和正硅酸乙酯(Si(OC2H5)4)为原料,采用溶胶凝胶法制备纳米硅酸钙粉体,通过热压烧结设备对粉体进行烧结,研究了烧结温度、烧结压力与保温时间对陶瓷性能的影响,并对所制备的陶瓷试样进行体外生物活性测试。结果表明:在烧结压力40 MPa,950℃保温25 min时所制备的硅酸钙陶瓷的抗强度达到241 MPa,维氏硬度达到668,模拟体液培养1天后试样表面出现羟基磷灰石(HA),培养15天后陶瓷表面的HA膜层厚度不断增加。     

58S生物玻璃陶瓷的力学性能及体外生物活性

以溶胶-凝胶58S生物玻璃为原料在1200℃煅烧制备了玻璃陶瓷块体。与700℃煅烧的玻璃(58S-700)相比，1200℃煅烧后的玻璃陶瓷(58S-1200)显示出较高的抗弯强度和致密度，X射线衍射分析其结晶相主要为硅灰石和二氧化硅。体外模拟体液浸泡实验表明：58S-700玻璃和58S-1200玻璃陶瓷都能诱导羟基磷灰石的沉积。体外成骨细胞培养结果显示：58S-700玻璃有利于细胞早期贴附，而58S-1200玻璃陶瓷较低的离子释放速度对细胞后期增殖有利。研究结果表明：58S-1200玻璃陶瓷不仅能诱导羟基磷灰石沉积，而且具有良好的细胞相容性和较高的力学强度，有可能成为一种骨替代和修复材料。     

稀土对激光熔覆生物陶瓷涂层性能的影响

采用激光熔覆的工艺方法制备出含稀土的硼CaP陶瓷涂层,通过X射线衍射仪(XRD)、扫描电镜(SEM)和体外模拟体液(SBF)浸泡实验,对涂层物相组成、组织形貌和生物活性进行了研究。结果表明添加稀土氧化物La2O3之后,羟基磷灰石衍射峰明显上升,晶粒明显细化,涂层表面沉积的类骨磷灰石明显增多,生物活性明显改善。     

焦磷酸盐微晶玻璃对β-磷酸三钙生物陶瓷的抗弯强度及生物活性的影响

通过熔融法制备组成为Na2O-MgO-CaO-P2O5的基础玻璃,在800℃进行热处理,得到主要组成为Na4P2O7和β-Ca2P2O7(β-calcium pyrophosphate,β-DCP)的焦磷酸盐微晶玻璃(pyrophosphate glass,PG).将PG和β-磷酸三钙(β-tricalcium phosphate,β-TCP)按质量比为10:90混合,干压成型,烧结制得PG/β-TCP生物陶瓷.采用差热分析、X射线衍射、扫描电镜、能谱、模拟体液浸泡等方法研究了基础玻璃的析晶、PG/β-TCP生物陶瓷材料体系的相组成、力学性能和生物活性.结果表明:PG能有效提高PG/β-TCP陶瓷的抗弯强度,1300℃烧结3h制备的PG/β-TCP陶瓷的弯曲强度与纯β-TCP陶瓷相比,由87.4MPa提高至113.2MPa;同时,PG可有效改善β-TCP基体的生物活性,在模拟体液中浸泡14d后,PG/β-TCP陶瓷表面形成Ca与P摩尔比为1.46的叶状磷灰石.     

Mg/HA复合生物材料的制备及表面生物活性评价

用纯镁做基体,以化学沉淀法制备的类球状纳米羟基磷灰石(HA)粉体为增强体,采用粉末冶金法制备了含HA40%的HA/Mg复合材料。对所制备复合材料的组织、物相以及在模拟体液(simulated body fluid,简称SBF)中的生物活性进行了研究。结果表明:HA相均匀分布于镁基体中,形成理想的网状组织结构;复合材料在烧结后内部相组成以HA和Mg为主,烧结过程中没有发生化学反应;随着浸泡时间的延长,表面沉积物质增多,对其进行能谱分析发现沉积物质富含Ca、P和C元素,分析认为生成物为含碳酸根的羟基磷灰石,说明复合材料具有较好的生物活性。     

富含钙磷的多孔氧化钛膜及其生物活化机理

在不同电压下,钛经微弧氧化在表面形成富含钙磷的多孔氧化钛膜。通过模拟体液浸泡实验检测磷灰石的形成以确定样品的生物活性。实验结果表明：不同电压制备的微弧氧化样品在模拟体液浸泡后,只有400 V和450 V的样品表面生成磷灰石层,说明高电压制备的样品具有生物活性;而低电压制备的微弧氧化样品在模拟体液中浸泡长达50 d仍未见到任何物质沉积,表明其不具有生物活性。分析认为,粗糙多孔的表面虽有利于磷灰石的成核,但高电压下出现的CaTiO_3相及其水解吸引钙、磷沉积才是磷灰石形成的主要原因。     

固化液组成对磷灰石/硅灰石生物玻璃骨水泥性能的影响

为了进一步提高磷灰石/硅灰石(apatitv-wollastonite,AW)生物玻璃骨水泥的性能,采用不同组成的柠檬酸/磷酸盐溶液作为固化液,与溶胶-凝胶法制备的AW生物玻璃调合制备了AW-玻璃骨水泥(AW-glassbone cement,AW-GBC).利用X射线衍射和扫描电镜对骨水泥的晶相组成和显微结构进行了研究,探讨了固化液组成对骨水泥固化时间、生物活性及力学性能的影响.结果表明:采用柠檬酸/K2HPO4/KH2PO4复合固化液制备的骨水泥固化后,浸泡于模拟体液7 d,即生成较多的羟基磷灰石,且抗压强度较高,说明复合固化液更有利于获得较高生物活性和力学性能的AW生物玻璃骨水泥.     

In-vitro bioactivity of wollastonite materials derived from limestone and silica sand

This paper describes the behaviour of bioactive wollastonite materials containing Malaysian limestone and silica sand. Wollastonite, which is also known as calcium silicate (CaSiO₃), is an industrial mineral composed of calcium, silicon and oxygen. Pseudowollastonite, which is a primary crystal of wollastonite, was synthesised via a solid-state reaction at a temperature of 1450 °C. The in-vitro bioactivity of wollastonite was examined by soaking it in simulated body fluid (SBF) solution for 1–7 days at 36.5 °C. The soaked wollastonite samples were characterised using XRD, SEM-EDX, FTIR and ICP analyses. Apatite particles precipitated on the surface of the wollastonite sample after the sample was soaked in the SBF. The XRD analysis indicated the presence of an increasing amount of the hydroxyapatite phase as the soaking time increased. The SEM and EDX analyses indicated the formation of granules of agglomerated apatite particles on the surface of the soaked wollastonite sample. During the formation of apatite, phosphate ions from the SBF solution were consumed. This process was confirmed by ICP, which revealed a decrease in ion concentration after the soaking process. The FTIR analysis indicated that the peaks of the phosphate ions increase when the apatite layer forms on the surface of the wollastonite sample. After the soaking process, a calcium deficient hydroxyapatite layer was observed on the wollastonite sample. The study concludes that wollastonite produced from Malaysian limestone and silica sand is bioactive and may be used as an implantable biomaterial.     

Dissolution properties of different compositions of biphasic calcium phosphate bimodal porous ceramics following immersion in simulated body fluid solution

Biphasic calcium phosphate (BCP) bimodal porous ceramics were prepared from a mixture of fine powders of hydroxyapatite (HAp) and beta-tricalcium phosphate (β-TCP) with varying HAp/β-TCP ratios. Two types of HAp powders and one type of β-TCP powder were used to produce porous BCP bioceramics with HAp/β-TCP weight ratios of 20/80, 40/60, and 80/20. Dissolution tests were performed to compare the dissolution properties of BCP-based bioceramics with different structural properties. Porous ceramic samples of approximately 0.5 g were individually soaked in 30 ml of simulated body fluid (SBF) solution at 36.5 °C for 1, 3, 7 and 10 days, respectively. The calcium content of the SBF solution was analyzed by ICP. The porous bodies were filtered, dried, and characterized using SEM, XRD, and FT-IR. The results indicate that the sample structural properties seem to have a greater effect than the storage environment on the dissolution properties.     

生理模拟液中的磷酸钙微晶玻璃的表面变化

应用玻璃结晶法制备了以磷酸钙为主体的多孔微晶玻璃载体材料。在一定的条件下对该药物载体材料进行了生理模拟液的浸泡实验,并用Fourier红外光谱和扫描电镜对其表面进行了表征分析。试验结果表明：经模拟液浸泡后,在材料的表面沉积了一定量的类骨磷灰石(碳酸羟基磷灰石),其形貌为球状颗粒,并证实了载体材料的粗糙表面有利于碳酸羟基磷灰石晶体的形成。研究结果有助于分析碳酸羟基磷灰石的形成机理及了解磷酸钙微晶玻璃载体材料在体内的骨诱导机理。     

Fabrication and characterization of 45S5 bioglass reinforced macroporous calcium silicate bioceramics

Bioactive and degradable macroporous bioceramics play an important role in clinical applications. In the present study, 45S5 bioglass reinforced macroporous calcium silicate ceramics (45BG-reinforced MCSCs) were fabricated. The effect of bioglass additives on compressive strength and open porosity of the samples was investigated, and the bioactivity and degradability of the obtained reinforced samples were also evaluated. The 45S5 bioglass additive was found to be effective to increase the strength of the MCSCs by the liquid-phase sintering mechanism. The optimum amount of bioglass additives was 5 wt.% and the compressive strength of the reinforced samples was approximately 2 times higher as compared to the pure macroporous calcium silicate ceramics (MCSCs). The compressive strength of the reinforced samples with about 50% porosity reached 112.47 MPa, which was similar to those of the cortical bones. After soaking in simulated body fluid (SBF), hydroxycarbonate apatite (HCA) layer was formed on the surface of the 45BG-reinforced MCSCs. Furthermore, the degradation rate of the reinforced samples was just about one-third of those pure MCSCs. Our results indicated that degradable 45BG-reinforced MCSCs possess excellent mechanical strength and bioactivity, and may be used as bioactive and degradable biomaterials for hard tissue prosthetics or bone tissue engineering applications.     

Mechanical properties and bioactivity of β-Ca2SiO4 ceramics synthesized by spark plasma sintering

Bioactive beta-dicalcium silicate ceramics (β-Ca₂SiO₄) were fabricated by spark plasma sintering (SPS). The relative density of as-prepared β-Ca₂SiO₄ ceramics reached 98.1% when sintered at 1150 °C, leading to great improvement in bending strength (293 MPa), almost 10 times higher than that of the specimen prepared by conventional pressureless sintering (PLS). High fracture toughness (3.0 MPa m^1/2) and Vickers hardness (5.8 GPa) of β-Ca₂SiO₄ ceramics were also achieved by SPS at 1150 °C. The simulated body fluid (SBF) results showed that β-Ca₂SiO₄ ceramics had a good in vitro bioactivity to induce hydraxyapatite (HAp) formation on their surface, which suggests that β-Ca₂SiO₄ ceramics are promising candidates for load-bearing bone implant materials.     

Study of the bioactivity of fluorophlogopite–whitlockite ceramics

Fluorophlogopite–whitlockite phase compositions containing ceramics were prepared using Egyptian raw materials. The in vitro studies confirmed the bioactivity of the prepared mixtures. Finely divided HA layer was formed on the surface of the ceramic samples after immersion in SBF. The morphology of finely divided HA grains was found to be needle-like crystalline aggregates. The contents of calcium cations measured in SBF increased on the seventh day, compared with the first day of immersion which is attributed to dissolution. The values of phosphorous cations were slightly reduced on the seventh day, compared with the first day of immersion that is attributed to the successive dissolution and precipitation.     

Synthesis and characterization of hydroxyapatite/β-tricalcium phosphate nanocomposites using microwave irradiation

Microwave assisted synthesis method is a relatively new approach employed to decrease synthesis time and form a more homogenous structure in biphasic calcium phosphate bioceramics. In this study, nanocrystalline HA/β-TCP composites were prepared by microwave assisted synthesis method and, for comparison reason, by conventional wet chemical methods. The chemical and phase composition, morphology and particle size of powders were characterized by FTIR, XRD and SEM, respectively. The use of microwave irradiation resulted in improved crystallinity. The amount of hydroxyapatite phase in BCP ranged from 5% to 17%. The assessment of bioactivity was done by soaking of powder compacts in simulated body fluid (SBF). The decreasing pH of the solution in the presence of β-TCP indicated its biodegradable behavior. Rod-like hydroxyapatite particles were newly formed during the treatment in SBF for microwave assisted substrate synthesis. In contrast, globular particles precipitate under same conditions if BCP substrates were synthesized using conventional wet chemical methods.     

Ultrafast bone-like apatite formation on bioactive tricalcium silicate cement using mussel-inspired polydopamine

The growing bone-like apatite layer at the tissue-implant interface is the essential condition for materials to bond robustly to surrounding bone and may provide a favorable environment for living bone formation. Inspired by versatility of mussel adhesive proteins, we developed an ultrafast and accessible route to accelerate effectively the formation of amorphous calcium phosphate (ACP), the precursor phase of bone-like apatite, on the surface of polydopamine (PDA)-coated tricalcium silicate (TCS) within 5?min in simulated body fluid (SBF). The key of the method lies in successful preparation of PDA coating on the surface of hydrated TCS by simple dip-coating of hydrated TCS in an aqueous solution of dopamine. A strong adsorption between PDA coating and surface of hydrated TCS could be formed via bidentate hydrogen and electrostatic bonds. After 7 d of soaking in SBF, the bone-like apatite layer on the surface of PDA-coated TCS disk, about 91.1?µm in height was thicker than that on the surface of pristine TCS disk, determining about 49.5?µm. The results indicate that PDA coating can facilitate the kinetic deposition of bone-like apatite on its surface. The abundant Ca²⁺ ions and the lower interface energy of ACP at the interface between ACP and surfaces of PDA-coated TCS disks are responsible for the ultrafast precipitation of ACP and formation of bone-like apatite layer which is carbonated hydroxyapatite (HA) confirmed by different analytical tools. The route can open avenues for development of PDA-coated TCS biomaterials for hard tissue repair and substitution.     

Characterization and in vitro-bioactivity of natural hydroxyapatite based bio-glass–ceramics synthesized by thermal plasma processing

Natural bovine hydroxyapatite/SiO₂–CaO–MgO glass–ceramics were produced using the transferred arc plasma (TAP) processing method. Homogeneous mixtures of HA/25 wt% SiO₂–CaO–MgO and HA/50 wt% SiO₂–CaO–MgO batches obtained by dry mixing the respective compositions in a ball mill were processed in argon plasma using the TAP torch at 5 kW for 1, 2 and 3 min, respectively. The synthesized glass–ceramic samples were studied for phase composition, microstructure and bioactivity. The phase study of the synthesized glass–ceramics revealed the formation of calcium phosphate silicate with traces of calcium silicate. The structural study by SEM revealed that the prepared samples possessed smooth glassy surface morphology. The in vitro-bioactivity of the TAP synthesized glass–ceramics was examined in simulated body fluid (SBF). The SBF test results confirmed the development of crystalline carbonated apatite phase after 12 days of immersion. The cytocompatibility was evaluated through human fibroblast cell proliferation. The fibroblasts culture results showed that the sample was non-toxic and promoted cell growth.