氟磷灰石-氟金云母微晶玻璃的生物活性研究

通过模拟细胞外液浸泡及动物骨内种植的方法研究了氟磷灰石-氟金云母微晶玻璃的生物活性机理。借助于SEM/EDAX,薄膜XRD,IRRS及原子吸收光谱分析等技术,研究了该微晶玻璃在生理环境中表面羟墓碘灰石层的形成过程。根据微晶玻璃中主晶相种类、显微结构特点及溶液中各离子的浓度等讨沦了羟基碑灰石层的形成机理。认为微晶玻璃中残余玻璃相的Ca~(2+)溶出及溶液相对于羟基磷灰石的过饱和状态,对材料表面羟基碑灰石层的形成具有重要意义。形成的羟基磷灰石层具有较低的结晶度,它是由最初的无定形态含水富CaO,P_2O_5薄层晶化转变而成。     

碳酸羟基磷灰石的生物矿化研究

采用湿化学法制备了B型替代为主的碳酸羟基磷灰石(CHA)和羟基磷灰石(HA).利用体外实验方法(in vitro)以及XRD、SEM、FTIR、AAS等手段研究了HA和CHA在模拟生理溶液(SBF)中的降解过程、表面反应产物和生物矿化机理.研究结果表明,CHA具有较高的生物活性,在SBF中浸泡后可形成表面类似天然骨中矿物的碳酸羟基磷灰石层(HCA).材料的组成、溶解度和表面能对矿化层微晶的成核有重要作用.     

生物活性玻璃的红外漫反射光谱研究

对傅立叶变换红外漫反射光谱分析(FTIR)技术在生物玻璃生物活性研究中的应用进行了分析论述，并对生物玻璃在模拟生理溶液(SBF)中反应不同时间其表面碳酸羟基磷灰石(HCA)的形成机理进行了理论探讨。     

稀土氧化钇改性磷酸钙骨水泥的研究

磷酸钙骨水泥是一种新型的自固化的非陶瓷羟基磷灰石人造骨材料,具有良好的生物相容性、自固化能力、易于塑形、与成骨活性相协调的溶解性能可作为药物、生物活性因子缓释载体等优越的性能。稀土掺杂羟基磷灰石,对羟基磷灰石的合成有促进作用,并且使其具有更稳定的性质。钇的加入有助于羟基磷灰石生物活性的提高。笔者利用钇掺改善羟基磷灰石生物活性作为探讨。其采用氧化钇对磷酸钙骨水泥进行改性研究,考察磷酸钙骨水泥凝结时间、可注射性和孔隙率等基本性能。采用X射线衍射分析骨水泥粉末在水化过程中的变化及其最终产物。采用电镜观察产物的微结构和表面形貌。研究结果表明:钇加入没有影响磷酸钙骨水泥的水化,并且随着钇含量的增加磷酸钙骨水泥的固化体凝结时间逐渐延长,其中氧化钇含量在5%时凝结时间最短;骨水泥浆体的可注射性变大,其中氧化钇含量在1.5%时可注射性最大(壳聚糖溶液)。磷酸钙骨水泥水化最终产物为片状或棒状的羟基磷灰石,其结构呈紧密联系,但表面有较多的孔隙,且随着钇含量的增加孔隙率有增加的趋势。     

溶胶-凝胶法制备铁磁性热种子材料

铁磁性微晶玻璃由于具有良好的磁性和生物活性,可以用来作为温热疗法治疗癌症的热种子材料。本文采用溶胶-凝胶法制备出SiO2-CaO-Fe2O3系基础铁磁性微晶玻璃,以及添加适量的Na2O、P2O5、FeO氧化物的铁磁性微晶玻璃。利用XRD测试样品中的晶相组成,采用VSM测试样品的磁性能数据。在模拟体液浸泡2-3周后,样品表面有羟基磷灰石层的形成,说明样品良好的生物活性。     

沉淀法制备硅酸钙及其体外生物活性的研究

采用沉淀法制备的硅酸钙粉体经成型,在1200℃下常压烧结,制备出高纯的硅酸钙陶瓷,通过模拟体液浸泡对其体外生物活性进行了研究。X射线衍射(XRD)和扫描电镜(SEM)的结果表明:在1200℃下烧结制得的硅酸钙陶瓷主晶相为β型硅酸钙(-βCS);在模拟体液中浸泡14d后其表面可见类骨羟基磷灰石生成,28d后生成大量羟基磷灰石。因此,沉淀法合成的硅酸钙具有良好的诱导类骨羟基磷灰石形成能力和体外生物活性。     

熔融法生物玻璃与溶胶-凝胶法生物玻璃的矿化特性研究

采用X射线衍射(XRD)、傅立叶转换红外光谱(FTIR)、扫描电镜(SEM)等方法对比分析了熔融法生物玻璃45S5与溶胶-凝胶法生物玻璃58S及77S的体外生物矿化性能,对它们表现出来的生物矿化性能差异进行初步的机理研究.结果表明,这3种生物玻璃中,58S具有最好的生物矿化性能,在37℃的模拟体液(simulated body fluid,SBF)中浸泡反应8 h即能在表面矿化形成结晶度较好的碳酸羟基磷灰石(HCA).     

磷灰石/硅灰石生物玻璃基骨水泥的溶胶-凝胶法制备及性能

为了获得高性能的玻璃基骨水泥,采用溶胶–凝胶法制备了磷灰石/硅灰石（apatite/wollastonite,AW）生物玻璃,将其作为固相粉末与柠檬酸固化液均匀混合制得了AW玻璃基骨水泥（glass-based bone cement,GBC）,探讨了溶胶–凝胶法制备的AW生物玻璃作为GBC固相粉末的可能性。用X射线衍射、红外光谱和强度测试仪对不同温度热处理的AW生物玻璃粉末的晶相转变以及骨水泥在人体模拟体液中浸泡不同时间后的晶相组成和抗压强度进行了研究。结果表明：AW生物玻璃粉末经700℃热处理后形成了硅灰石和羟基磷灰石晶相,且温度越高晶相越完整;以900℃热处理后的AW生物玻璃粉末作为固相所制备的GBC随着浸泡时间的增加,骨水泥固化体中生成了更多量的CaCO3晶体及少量的羟基磷灰石晶体,且此种GBC的抗压强度最大。     

双相HA/β-TCP陶瓷的多孔结构对类骨磷灰石形成的影响

本文利用添加不同微孔造孔剂的方法来改善双相陶瓷的多孔结构；通过对不同多孔结构磷酸钙陶瓷在静态和动态模拟体液(simulated body fluid,SBF)中类骨磷灰石形成的比较研究，探索磷酸钙陶瓷类骨磷灰石形成的影响因素，从而为理解其体内形成骨的机理提供依据。结果表明：双相HA／β-TCP多孔材料的贯通性和贯通通道尺寸对类骨磷灰石形成的影响大，贯通通道尺寸应大于20μm。     

磷灰石/硅灰石生物玻璃基骨水泥的溶-凝胶法制备及性能

为了获得高性能的玻璃摹骨水泥,采用溶胶-凝胶法制备了磷灰石/硅灰石(apatite/wollastonite,AW)生物玻璃,将其作为固相粉末与柠檬酸固化液均匀混合制得了AW玻璃基骨水泥(glass-based bone cement,GBC),探讨了溶胶-凝胶法制备的AW生物玻璃作为GBC固相粉末的可能性.用X射线衍射、红外光谱和强度测试仪对不同温度热处理的AW生物玻璃粉末的晶相转变以及骨水泥在人体模拟体液中浸泡不同时间后的晶相组成和抗压强度进行了研究.结果表明:AW生物玻璃粉末经700℃热处理后形成了硅灰石和羟基磷灰石晶相,且温度越高晶相越完整;以900℃热处理后的AW生物玻璃粉末作为固相所制备的GBC随着浸泡时间的增加,骨水泥固化体中生成了更多量的CaC03晶体及少量的羟基磷灰石晶体,且此种GBC的抗压强度最大.     

X-ray Photoelectron Spectroscopy Study on the Process of Apatite Formation on a Sodium Silicate Glass in Simulated Body Fluid

The process of apatite formation on the surface of Na₂O–SiO₂ glass in a body environment was investigated, mainly by X-ray photoelectron spectroscopy, as a function of soaking time in a simulated body fluid (SBF). The glass was found to release Na⁺ ions via exchange with H₃O⁺ ions in the SBF to form Si—OH groups on its surface. These Si—OH groups induced apatite formation indirectly, by forming calcium silicate and amorphous calcium phosphate. The formation of the calcium silicate and amorphous calcium phosphate is attributed to electrostatic interactions between the Si—OH groups on the glass surface and the calcium and phosphate ions in the SBF.     

Bonelike Apatite Formation Induced on Zirconia Gel in a Simulated Body Fluid and Its Modified Solutions

Formation of bonelike apatite on zirconia gel in a simulated body fluid (SBF) with ion concentrations almost equal to those in human blood plasma, in modified SBF solutions to have increased pH values, and modified SBF solutions to have increased concentrations of calcium and phosphate ions has been investigated. The zirconia gel forms apatite on its surface in SBF, indicating that Zr-OH groups, abundant on the gel, act as effective apatite nucleation centers. Apatite formation is accelerated by increases in pH and in the concentration of calcium and phosphate ions, which is explained by an increase in the ionic activity product of the apatite in the SBF. These results suggest that zirconia ceramics may exhibit a bone-bonding ability by forming an apatite layer on their surfaces in the living body when they are modified to have many Zr-OH groups on their surfaces.     

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.     

Bioactivity modulation of Bioglass® powder by thermal treatment

A discussion of the effects of Bioglass^® powder crystallisation on the in vitro bioactivity in simulated body fluid (SBF) is presented.Starting from Bioglass^® powder, different glass–ceramics were obtained by thermal treatments between 580 °C and 800 °C, with variable crystallisation content (from 10 to 92 wt%). All samples (glass and glass–ceramics) showed apatite formation at their surface when immersed in SBF. In case of the glass and the samples with lowest crystallinity, the first step of apatite formation involved a homogenous dissolution followed by an amorphous calcium phosphate (CaP) layer precipitation. For the samples with a high crystallisation content, heterogeneous dissolution occurred. For the first time, the Stevels number of the amorphous phase is used to explain the possible dissolution of the crystalline phase present in materials with a similar chemical composition of the Bioglass^®. All samples presented at 21 days of immersion in SBF B-type hydroxycarbonate apatite crystals.     

Preparation of bioactive sodium titanate ceramics

The in vitro bioactivity of sol–gel derived sodium titanates with different sodium contents was investigated. Calcined sodium titanates show bioactive behaviour when exposed to simulated body fluid (SBF). A higher sodium content entails higher bioactivity since a higher amount of sodium ions is available for the exchange with H₃O⁺ ions from SBF, which results in the formation of Ti–OH groups and subsequently in the formation of an intermediate calcium titanate. The local pH increase triggers the formation of a biomimetic calcium phosphate layer on the surface. Sintering the samples leads to more crystalline sodium tri- and hexatitanate structures and a decrease of the sodium content. The amount of Na⁺ ions that can be released from the sodium titanate surface decreases due to a decreasing surface area and the reduced sodium content. As a result bioactivity is lost. Bioactive behaviour can be re-achieved by a subsequent chemical treatment of sintered sodium titanate ceramics in an aqueous NaOH solution.     

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.     

In vitro assessment of degradation and bioactivity of robocast bioactive glass scaffolds in simulated body fluid

In this study porous three-dimensional scaffolds of borate (13-93B3) bioactive glass were prepared by robocasting and in vitro degradation and bioactivity was evaluated. Grid like scaffolds with interconnected pores was assembled using robotic deposition technique which is a direct ink writing method. After binder burnout, the constructs were sintered for 1 h at 560 °C to produce scaffolds (porosity≈60%) consisting of dense glass struts (300±20 μm in diameter) and interconnected pores of width 580±20 μm. Hydroxyapatite formation on borate bioactive glass scaffolds was investigated in simulated body fluid (SBF) using three different scaffold/SBF (S/S) ratios (1, 2 and 10 mg/ml) at 37 °C. When immersed in SBF, degradation rate of the scaffolds and conversion to a calcium phosphate material showed a strong dependence to the S/S ratio. At high solid concentration (10 mg/ml) surface of the glass scaffolds converted to the calcium rich amorphous calcium phosphate after 30 days. At lower solid concentrations (2 and 1 mg/ml) an amorphous calcium phosphate layer formation was observed followed by the conversion to hydroxyapatite.     

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.     

Surface Potential of Poly(lactic acid) Composites Containing Calcium Carbonates in Simulated Body Fluid

The surface of a poly(lactic acid) composite (CCPC) containing calcium carbonate was reported to show apatite formation in simulated body fluid (SBF) within 24 h at 37°C. In the present work, ζ potentials of CCPC were examined to determine the rapid apatite formation mechanism at an early stage after soaking in SBF. The ζ potentials of CCPC showed negatively charged values in SBF. The potential decreased immediately after soaking, and subsequently increased during 1–6 h of soaking. After 6–9 h of soaking, no change in ζ potentials was observed. Laser Raman spectroscopy results suggested that the change in the ζ potential is closely related to the amount of Ca²⁺-coordinated carboxy groups on the CCPC surface. The concentration of phosphate ion in SBF decreased after 6 h. Apatite formation was suggested to begin after 6–9 h of soaking via Ca²⁺ coordination to carboxy groups and the subsequent adsorption of phosphate ions.     

Apatite Formation on Calcium Phosphate Invert Glasses in Simulated Body Fluid

Calcium phosphate invert glasses, which contain P₂O₇²⁻ and PO₄³⁻ ions, have been prepared via the addition of a small amount of TiO₂. The formation of bonelike calcium phosphate apatite on the surface of the phosphate invert glasses was examined in simulated body fluid (SBF) at a temperature of 37°C. Soaking for 20 d resulted in the deposition of leaflike apatite particles on 6CaO·3P₂O₅·TiO₂ invert glass (based on molar ratio). The glass had much-greater chemical durability against SBF, in comparison with a metaphosphate glass; P ions were not dissolved excessively from the 6CaO·3P₂O₅·TiO₂ glass, so the apatite formation was not suppressed.