生物活性玻璃/聚乳酸组织工程支架在SBF溶液中的降解和矿化性能

利用扫描电镜、X衍射仪以及红外漫反射仪,并通过对生物活性玻璃/聚乳酸组织工程支架在模拟体液（SBF）中失重率及模拟体液pH值的变化的检测,系统研究了生物活性玻璃/聚乳酸组织工程支架在SBF中的降解和矿化性能。结果发现：随着含有生物活性玻璃的聚乳酸支架在SBF溶液中浸泡时间的增长,SBF的pH值不断下降;含有生物活性玻璃...     

生物活性玻璃/PLA-PEG-PLA/聚乳酸组织工程支架在SBF溶液中的降解和矿化

通过测定pH值、质量损失率、SEM、XRD和FTIR,系统研究了生物活性玻璃/聚乳酸-聚乙二醇-聚乳酸嵌段共聚物（PLA-PEG-PLA）/聚乳酸组织工程支架在模拟体液（SBF）中的降解和生物矿化性能。研究结果表明：随着支架在SBF溶液中浸泡时间的延长,SBF的pH值和支架的质量呈下降趋势;生物活性玻璃的存在使pH值升高,而PLA-PEG-PLA嵌段共聚物的存在使pH值降低。XRD、FTIR图谱和SEM图像表明：在SBF中浸泡一定时间后,有无定型或结晶不完善的磷灰石在生物活性玻璃/PLA-PEG-PLA/聚乳酸组织工程支架表面沉积形成,并且PLA-PEG-PLA共聚物降解速度比聚乳酸快;在SBF中浸泡7天后,PLA-PEG-PLA共聚物的含量已经很难通过FTIR检测出来。     

CaO-P2O5-SiO2系统溶胶-凝胶玻璃的生物矿化行为

利用体外实验方法(in vitro)以及XBD、SEM、FTIR、BET、ICP等手段研究了两种溶胶一凝胶生物活性玻璃的显微结构及其在模拟生理溶液(SBF)中的降解过程、表面反应产物和生物矿化机理．结果表明，两种生物活性玻璃都具有较高的生物活性，均具有由纳米尺寸颗粒相互连接而成的微孔结构和较大的比表面积，在模拟生理溶液(SBF)中浸泡后可形成表面类似天然骨中无机矿物的碳酸经基磷灰石层(HCA)，说明两者均具有较高的生物活性和生理环境相应特性．材料表面的硅酸凝胶层及其硅经基团的形成对碳酸经基磷灰石(HCA)微晶的成核有重要作用。     

Sol-gel生物活性玻璃体外矿化沉积的动态/静态体外模拟系统对比研究

采用溶胶-凝胶法制备了CaO-P2O3-SiO2系统生物活性玻璃粉体,并通过成型烧结工艺制成多孔材料,对比研究了样品在动态和静态2种体外模拟实验系统中的材料矿化沉积,通过测量溶液pH值,Ca^2 浓度,及样品的XRD、SEM、FTIR测试,证明了动态体外模拟系统可以更好地模拟体内环境,生物活性玻璃材料在2种模拟系统中表面都有碳酸羟基磷灰石生成。     

Sol-Gel生物活性玻璃降解性能及矿化沉积的体外模拟研究

本研究采用溶胶-凝胶法制备了CaO-P2O5-SiO2系统生物活性玻璃粉体,并通过成型、烧结工艺制成多孔材料,样品在体外模拟实验系统中进行材料降解性能研究.通过测量溶液pH值、Ca2 浓度及样品的XRD、SEM、FTIR测试,认为生物活性玻璃本身发生降解的同时表面有一层类骨碳酸羟基磷灰石生成.     

不同模拟体液对硼硅酸盐生物活性玻璃基骨水泥矿化性能的影响

硼硅酸盐生物活性玻璃基(Borosilicate bioactive glass-based, BBG)骨水泥由于其优异的生物活性和生物降解性, 在治疗骨质疏松性骨折以及骨肿瘤、骨创伤、骨髓炎等疾病方面具有重要的应用前景, 受到人们的广泛关注。为进一步了解氨基酸对其植入生物体内后的矿化影响, 本研究在常规的SBF溶液中添加了不同种类及浓度的氨基酸物质, 重点研究对植入体表面形貌的影响。同时为在矿化过程中同步形成白磷钙矿(Whitlockite, WH)和羟基磷灰石(hydroxyapatite, HA), 调整了SBF溶液的温度以及酸碱度和Mg²⁺浓度, 研究了不同SBF溶液中BBG骨水泥表面形成的矿化产物。研究结果表明, 不同的氨基酸及浓度的变化对矿化产物的影响有较大差异, 天冬氨酸和赖氨酸的浓度变化影响矿物的长径比, 而甘氨酸对矿物形貌的影响较小。将硼硅酸盐生物活性玻璃压片放置在70 ℃下的高Mg²⁺浓度的酸性(pH=3.5)SBF溶液中浸泡一定时间后, 能够获得HA/WH的复相矿物。     

磷灰石-硅灰石多孔玻璃陶瓷的制备与晶相结构研究

采用溶胶-凝胶法制备磷灰石-硅灰石(AW)生物活性玻璃陶瓷纳米前驱体粉末,前驱体粉末经热处理后,采用有机泡沫漫渍成型,烧结制备了多孔AW生物活性玻璃陶瓷.通过差热和热重分析、X射线衍射分析、红外图谱分析、扫描电镜、透射电镜等分析测试方法,对AW前驱体粉末的微观结构,及其在煅烧过程中的晶相转变进行了研究,确定了制备纳米级AW前驱体粉的最佳工艺条件,推测出微晶玻璃体中各晶相的析出温度,确定了溶胶-凝胶法制备多孔AW玻璃陶瓷的煅烧工艺,体外模拟体液浸泡实验表明材料具有较高的矿化功能和生物活性.     

CaO-P2O5-SiO2溶胶凝胶玻璃在模拟体液中HCA层形成的研究

采用溶胶凝胶法制备了高硅含量的CaO-P2O5-SiO2系统玻璃.组成范围为(mol%)CaO13～18,P2O5 3～6,SiO2 78～83.样品采用体外溶液实验(in vitro)方法,在模拟体液(SBF)内浸泡不同时间.通过测定样品在SBF浸泡不同时间的溶液pH值变化,并对样品采用XRD、SEM等测试技术,研究了样品表面碳酸羟基磷灰石(HCA)层的形成机理及形貌变化.结果表明SiO2含量达78～83 mol%时玻璃仍具有很高的生物活性.玻璃表面在SBF中24 h内已开始形成HCA层,第3天已呈稳定态并布满整个表面,浸泡10d后的HCA由粒径在0.5～2.0 μm的球形颗粒构成.球形颗粒是纳米级HCA微晶聚集而成的多晶体.     

生物玻璃矿化性能及其离子溶出对成骨细胞功能的影响

通过体外矿化实验, 对比研究了熔融法生物玻璃45S5和溶胶－凝胶法生物玻璃58S、77S的生物矿化性能的差异;并运用了这三种生物玻璃的DMEM(Dulbecco’s Modified Eagle Medium)浸提液对MC-3T3细胞进行培养, 以考察不同生物玻璃在培养液中的离子溶出对成骨细胞增殖及ALP(碱性磷酸酶)活性的影响. 通过体外矿化实验可以发现, 77S的生物矿化性能相对45S5和58S较差, 在SBF溶液(模拟体液)中浸泡96h只能形成HA(羟基磷灰石)晶体, 45S5和58S则能生成类骨HCA(碳酸羟基磷灰石)晶体; 但细胞培养实验发现, 77S浸提液中培养的细胞, 其细胞增殖和ALP活性都明显高于45S、58S和对照组. 由此认为, 一定的离子浓度范围内, Si离子的存在有利于成骨细胞的增殖与分裂.     

pH值对溶胶凝胶-燃烧合成纳米晶LaMnO_3粉末的影响

以硝酸镧、硝酸锰和柠檬酸为原料,采用溶胶凝胶燃烧合成技术制备了超细LaMnO3粉末。借助XRD、DTA、SEM、FT-IR等分析仪器研究了溶胶凝胶-燃烧合成技术合成超细LaMnO3粉末的过程,着重讨论了前驱体溶液不同pH值对溶胶凝胶燃烧合成过程及合成产物的影响。结果发现,采用溶胶凝胶燃烧合成技术能合成纳米晶的LaMnO3粉末,随前驱体溶液pH值增加,燃烧反应速率增加,合成粉体的平均晶粒尺寸随pH值增加而减小。通过控制前驱体溶液pH值能一步合成超细LaMnO3颗粒(粒径200nm)。     

Differences in dry and wet grinding with a high solid concentration of coking coal using a laboratory conical ball mill: Breakage rate,morphological characterization,and induction time

This study explored the influence of wet and dry grinding conditions on breakage rate, shape factor and surface roughness of ground particles, induction time (the threshold for particle–bubble attachment to occur), and flotation recovery. The experimental results indicated that the dry grinding breakage rate was much higher than the wet grinding one. The first-order region was limited to a relatively short grinding time, where it was considered that little or no secondary breakage occurred. With the increasing time, the dry grinding breakage rate increased, while it decreased for wet grinding (solid concentration of 70 vol.%). The differences in shape factor and surface roughness of the wet- and dry-ground samples were attributed to different breakage mechanisms and grinding energy amounts generated by those two types of procedures. The wet-ground particles were characterized by more irregular shape factors and smoother surfaces, and thus presented shorter induction times and higher floatation recoveries compared to the dry-ground ones.     

通过仿生法在硅橡胶表面制备磷灰石薄膜的研究

用CaCl2的乙醇溶液和K2HPO4溶液对硅橡胶进行预处理,将处理过的硅橡胶分别浸渍于模拟体液和钙磷饱和溶液中来制备磷灰石薄膜.利用薄膜X射线衍射、红外吸收光谱和扫描电子显微镜对形成的薄膜进行了表征.结果表明,分别在模拟体液中7d和在钙磷饱和溶液中5d后,硅橡胶表面形成了一层磷灰石薄膜;在模拟体液中的薄膜表面呈网状并分布有许多球状晶粒,在钙磷饱和溶液中的薄膜为结晶良好的片状晶体.     

一种新型仿生骨组织工程支架的制备与表征

利用改性生物玻璃粉体和胶原、透明质酸钠、磷酸丝氨酸等天然生物分子复合制备仿生型三维多孔骨组织工程支架材料,利用体外模拟实验结合SEM、FTIR、XRD 等测试方法对材料的显微结构、生物矿化性能进行了综合研究,研究表明该材料具有良好的孔隙结构,在模拟生理溶液(SBF)中反应24h即可在支架表面形成碳酸羟基磷灰石(HCA).     

The mechanism of biomineralization of bone-like apatite on synthetic hydroxyapatite: an in vitro assessment.

The mechanism of biomineralization of bone-like apatite on synthetic hydroxyapatite (HA) has been investigated in vitro, in which the HA surface was surveyed as a function of soaking time in simulated body fluid (SBF). In terms of surface structure by transmission electron microscopy with energy-dispersive X-ray spectrometry, the HA whose Ca/P atomic ratio was 1.67 revealed three different characteristic soaking periods in SBF, i.e. the first soaking period, in which the HA surface increased the Ca/P ratio up to 1.83 to form an amorphous phase of Ca-rich calcium phosphate; the second soaking period, in which the HA surface decreased the Ca/P ratio up to 1.47 to form an amorphous phase of Ca-poor calcium phosphate; and the third soaking period, in which the HA surface gradually increased the Ca/P ratio up to 1.65 to eventually produce the bone-like nano-cerystallites of apatite, which grew forming complex crystal assemblies with a further increase in immersion time. Analysis using electrophoresis spectroscopy indicated that, immediately after immersion in SBF, the HA revealed a highly negative surface potential, which increased to reach a maximum positive value in the first soaking period. The surface potential then decreased to again reach a negative value in the second soaking period and thereafter converge to a constant negative value in the third soaking period. This implies that the HA induces biomineralization of apatite by smartly varying its surface potential to trigger an electrostatic interaction, first with positive calcium ions and second with negative phosphate ions in the SBF.     

Highly adherent bioactive glass thin films synthetized by magnetron sputtering at low temperature

Thin (380–510 nm) films of a low silica content bioglass with MgO, B₂O₃, and CaF₂ as additives were deposited at low-temperature (150°C) by radio-frequency magnetron sputtering onto titanium substrates. The influence of sputtering conditions on morphology, structure, composition, bonding strength and in vitro bioactivity of sputtered bioglass films was investigated. Excellent pull-out adherence (~73 MPa) was obtained when using a 0.3 Pa argon sputtering pressure (BG-a). The adherence declined (~46 MPa) upon increasing the working pressure to 0.4 Pa (BG-b) or when using a reactive gas mixture (~50 MPa). The SBF tests clearly demonstrated strong biomineralization features for all bioglass sputtered films. The biomineralization rate increased from BG-a to BG-b, and yet more for BG-c. A well-crystallized calcium hydrogen phosphate-like phase was observed after 3 and 15 days of immersion in SBF in all bioglass layers, which transformed monotonously into hydroxyapatite under prolonged SBF immersion. Alkali and alkali-earth salts (NaCl, KCl and CaCO₃) were also found at the surface of samples soaked in SBF for 30 days. The study indicated that features such as composition, structure, adherence and bioactivity of bioglass films can be tailored simply by altering the magnetron sputtering working conditions, proving that this less explored technique is a promising alternative for preparing implant-type coatings.     

A study of apatite formation on natural nano-hydroxyapatite/chitosan composite in simulated body fluid

This study is focused on the ability of apatite formation on the surface of nano-hydroxyapatite (HA)/chitosan (CH) composite in simulated body fluid (SBF) in vitro. At first, natural nano-HA was prepared according to a wet-balling method and the composite was prepared by combining the natural nano-hydroxyapatite and chitosan, and then in vitro biomineralization test of natural nano-HA/CH composite was carried out in standard SBF. Subsequently, the quantity of the weight of the particles formed on the composite surface in SBF was measured by analytical balance, and the morphology change on the surface of the composite was observed by a scanning electron microscope (SEM). Lastly, a Fourier transform infrared spectroscope (FTIR) was used to investigate the chemical components of the particles formed on the natural nano-HA/CH composite surface in SBF. The result of quantity assessment shows that the weight of the composite increased with the increase of soaking time. The SEM image shows that the particles were gradually formed on natural nano-HA/CH composite surface, and the FTIR spectrum of the particles on composite surface confirms that these particles were carbonate apatite. This study indicates that the nano-HA/CH composite has a good ability for apatite formation in SBF, which predicts the bone-inducing ability of natural nano-HA/CH composite in vivo.     

A study of apatite formation on natural nano-hydroxyapatite/ chitosan composite in simulated body fluid

This study is focused on the ability of apatite formation on the surface of nano-hydroxyapatite (HA)/chitosan (CH) composite in simulated body fluid (SBF) in vitro. At first, natural nano-HA was prepared according to a wet-balling method and the composite was prepared by combining the natural nano-hydroxyapatite and chitosan, and then in vitro biomineralization test of natural nano-HA/CH composite was carried out in standard SBF. Subsequently, the quantity of the weight of the particles formed on the composite surface in SBF was measured by analytical balance, and the morphology change on the surface of the composite was observed by a scanning electron microscope (SEM). Lastly, a Fourier transform infrared spectroscope (FTIR) was used to investigate the chemical components of the particles formed on the natural nano-HA/CH composite surface in SBF. The result of quantity assessment shows that the weight of the composite increased with the increase of soaking time. The SEM image shows that the particles were gradually formed on natural nano-HA/CH composite surface, and the FTIR spectrum of the particles on composite surface confirms that these particles were carbonate apatite. This study indicates that the nano-HA/CH composite has a good ability for apatite formation in SBF, which predicts the bone-inducing ability of natural nano-HA/CH composite in vivo.     

Bioactivity of wollastonite/aerogels composites obtained from a TEOS–MTES matrix

Organic–inorganic hybrid materials were synthesized by controlled hydrolysis of tetraethoxysilane (TEOS), methyltrimethoxysilane (MTES), synthetic wollastonite powders and polydimethylsiloxane (PDMS) in an ethanol solution. Aerogels were prepared from acid hydrolysis of TEOS and MTES with different volume ratio in ethanol, followed by addition of wollastonite powder and PDMS in order to obtain aerogels with 20 wt% of PDMS and 5 wt% of CaO of the total silica. Finally, when the wet gels were obtained, they were supercritically dried at 260 °C and 90 bar, in ethanol. In order to obtain its bioactivity, one method for surface activation is based on a wet chemical alkaline treatment. The particular interest of this study is that we introduce hybrid aerogels, in a 1 M solution of NaOH, for 30 s at room temperature. We evaluate the bioactivity of TEOS–MTES aerogel when immersed in a static volume of simulated body fluid (SBF). An apatite layer of spherical-shaped particles of uniform size smaller than 5 microns is observed to form on the surface of the aerogels after 25 days soaking in SBF.     

微波辅助法制备镁合金的植酸镁/羟基磷灰石复合涂层及其耐蚀性能

采用微波辅助法在AZ31镁合金表面制备了植酸镁/羟基磷灰石(PA/HA)复合涂层。利用FESEM、EDS、XRD和电化学性能测试等方法表征涂层的表面形貌、物相组成以及耐蚀性能,探究了植酸溶液的pH值对PA/HA复合涂层形貌及耐蚀性能的影响,并通过浸泡实验研究了镁合金及PA/HA复合涂层在模拟体液(SBF)中的降解矿化行为。结果表明:在植酸预处理中,植酸溶液的pH=5.0时制备得到的PA/HA复合涂层表面均匀、无裂纹,与镁合金基底的界面结合良好;并且在此pH值下PA/HA复合涂层包覆镁合金样品的交流阻抗最大,自腐蚀电流密度最小,说明其耐蚀性最好。在SBF中,PA/HA复合涂层能够快速诱导磷灰石的生成,并显著提高镁合金基底的耐蚀性能。     

Seeded growth of hydroxyapatite in simulated body fluid

The precipitation of calcium phosphates was investigated, in simulated body fluid (SBF), pH 7.40 and 37°C. The kinetics of the mineral phase forming in the SBF was measured using the constant supersaturation method. The approach provides a detailed investigation in the processes taking place in the SBF which is widely used for the study of biomineralization. The pH adjustment was done by a pH-stat instead of Tris-Buffer [Tris (hydroxymethyl) Aminomethane] to avoid the presence of organic soluble compounds. The stability of SBF was investigated and the stable supersaturated solutions were seeded. The technique of seeded precipitation was employed for the achievement of accurate and reproducible kinetics measurements. The crystal growth experiments in which SBF solutions of variable supersaturations were seeded with hydroxyapatite [Ca₅(PO₄)₃OH, HAP] crystals showed that the precipitation of calcium phosphates took place exclusively on specific active sites provided on the surface of the synthetic seed crystals. The crystal growth mechanism showed that the process was controlled by surface diffusion. The phase formed was HAP in the lattice of which CO₃²⁻ and Mg²⁺ ions were incorporated. SBF was the source of these ions. Moreover it was found that the less stable calcium phosphate dihydrate (CaHPO₄·2H₂O, DCPD) may form as a transient phase hydrolyzing rapidly into the more stable HAP. Morphological examination of the carbonated apatites formed in the SBF showed appreciable aggregation.