Na_2O-CaO-SiO_2-P_2O_5系统生物玻璃析晶对其生物活性及强度的影响

Na2 O- Ca O- Si O2 - P2 O5系统生物活性玻璃具有较高的生物活性 ,是一种理想的骨缺损填充材料。为了提高该生物玻璃的力学强度 ,对其进行了微晶化处理 ,并利用 XRD、SEM、FTIR分析及 SBF浸泡等技术对其生物活性与母体玻璃进行了分析比较 ,并测定和比较了晶化前后材料的抗折强度和断裂韧性 ,对材料的生物活性机理进行了理论分析     

HA混合生物玻璃制备TCP陶瓷支架及其性能的研究

磷酸钙陶瓷以其优良的生物兼容性与生物可降解性在组织工程学里被广泛应用,但较低的力学性能制约了其发展。羟基磷灰石(HA)混合一定量的生物玻璃,调节羟基磷灰石的磷钙比制得多孔磷酸三钙(TCP)陶瓷支架。实验表明当羟基磷灰石与生物玻璃的混合比在8:2的时候,并在1 400℃下灼烧3 h,可制得磷酸三钙陶瓷支架,经力学测试结果此支架的抗压强度为9.98 MPa;通过模拟人体体液分析得出此支架具有良好的生物活性,并通过9 h的细胞增殖实验得出此支架具有较好的生物相容性。因此用羟基磷灰石与生物玻璃制得的磷酸三钙支架不但具有较好的力学性能,而且具有良好的生物活性与生物相容性,在生理环境中能促进细胞的分裂增殖,最终使骨缺损部位完全被新的骨组织所取代。     

羟基磷灰石与生物活性玻璃的 口腔临床对比研究

随机选择种植体周围炎和骨缺损的病人进行羟基磷灰石 HA和生物活性玻璃 BAG治疗的对比研究 ,所有病人均采用常规翻瓣手术 ,植入 HA( 10例 )或 BAG( 8例 ) ,通过临床观察发现 HA均存在一定的排异现象 ,而 BAG明显无排异性 ,效果良好。作者认为 BAG具有骨引导和骨形成性 ,与机体骨组织形成化学键合 ,与骨组织和软组织有良好的亲和性 ,有良好的临床运用前景     

多孔TCP陶瓷支架的制备及其性能研究

目的 生物陶瓷作为骨修复材料已经得到广泛使用,研究多孔磷酸三钙(TCP)生物陶瓷的制备方法及性能.方法 以羟基磷灰石(HA)为原料,通过加入钙磷生物玻璃调节钙磷比,在高温加热过程中实现多孔TCP陶瓷支架的制备.结果 经测试用这种方法制得的TCP支架比单纯用TCP粉末制得的TCP支架具有更高的机械强度,其强度可达9.11...     

R2O—A12O3—B2O3—SiO2系统玻璃、超细α—Al2O3对羟基磷灰石陶瓷的烧结和相变的影响

系统地研究了R2O-A12O3-B2O3-SiO2系统玻璃和超细α—Al2O3对羟基磷灰石(HAP)陶瓷的烧结和相变及机械性能的影响。结果表明α—Al2O3对HAP的烧结有阻碍作用，使烧结温度提高；在烧结过程中能抑制玻璃与羟基磷灰石作用，使羟基磷灰石在烧结温度下避免脱去羟基而分解。同时使用超细α—Al2O3和玻璃复合增强HAP可以取得较好的效果，当α-Al2O3含量为10％(wt)，玻璃含量为20％(wt)时，在1200℃下烧结1h可以获得弯曲强度高达106MPa的复相HAP陶瓷。     

R2O-Al2O3-B2O3-SiO2系统玻璃、超细α-Al2O3对羟基磷灰石陶瓷的烧结和相变的影响

系统地研究了 R2 O- Al2 O3- B2 O3- Si O2 系统玻璃和超细α- Al2 O3对羟基磷灰石 (HAP)陶瓷的烧结和相变及机械性能的影响。结果表明α- Al2 O3对 HAP的烧结有阻碍作用 ,使烧结温度提高 ;在烧结过程中能抑制玻璃与羟基磷灰石作用 ,使羟基磷灰石在烧结温度下避免脱去羟基而分解。同时使用超细α- Al2 O3和玻璃复合增强 HAP可以取得较好的效果 ,当α- Al2 O3含量为 10 % (wt) ,玻璃含量为 2 0 % (wt)时 ,在 12 0 0℃下烧结 1h可以获得弯曲强度高达 10 6 MPa的复相 HAP陶瓷     

生物玻璃-纳米羟基磷灰石梯度涂层的生物相容性研究

目的对生物玻璃-纳米羟基磷灰石(BG-nHA)梯度涂层的生物相容性作初步的评价。方法用低温烧结法在钛合金表面制备生物玻璃纳米羟基磷灰石梯度涂层,利用L929细胞检测梯度涂层材料的细胞毒性。取体外分离培养扩增的人骨髓基质干细胞(hBMSC),接种于涂层材料上,通过绿色荧光蛋白染色、扫描电镜和MTT法观察细胞的黏附和生长情况。结果生物玻璃-纳米羟基磷灰石梯度涂层的细胞毒性分级为1级,人骨髓基质干细胞可以在涂层材料表面黏附和生长。结论生物玻璃-纳米羟基磷灰石梯度涂层有良好的生物相容性,具有潜在的临床应用前景。     

生物玻璃-纳米羟基磷灰石梯度涂层的生物相容性研究

目的 对生物玻璃-纳米羟基磷灰石(BG-nHA)梯度涂层的生物相容性作初步的评价.方法 用低温烧结法在钛合金表面制备生物玻璃纳米羟基磷灰石梯度涂层,利用L929细胞检测梯度涂层材料的细胞毒性.取体外分离培养扩增的人骨髓基质干细胞(hBMSC),接种于涂层材料上,通过绿色荧光蛋白染色、扫描电镜和MTT法观察细胞的黏附和生长情况.结果 生物玻璃-纳米羟基磷灰石梯度涂层的细胞毒性分级为1级,人骨髓基质干细胞可以在涂层材料表面黏附和生长.结论 生物玻璃-纳米羟基磷灰石梯度涂层有良好的生物相容性,具有潜在的临床应用前景.     

钛合金表面新型生物玻璃/羟基磷灰石涂层的体内动物实验

目的为促进钛合金植入体与骨的结合,在其表面制备了生物玻璃/羟基磷灰石复合涂层,并植入兔子股骨内进行动物试验,采用等离子喷涂羟基磷灰石涂层和未涂层的Ti6Al4V合金作为对照。方法种植到期的植入体取出后进行组织学切片,采用品红-苦味酸染色后进行组织学观察,采用SEM高倍观察种植体与骨的结合界面,并对骨接触率和凹槽内骨长入量进行了统计分析和比较。结果三种植入体都具有良好的生物相容性。Ti6Al4V合金与骨之间是一种形态固定,而生物玻璃/羟基磷灰石涂层、等离子喷涂羟基磷灰石涂层可与骨形成骨键合。生物玻璃/羟基磷灰石涂层在植入期间与基体没有脱落,同时其与骨的接触率和凹槽内骨长入量要明显高于其余两个植入体,显示出促进骨生长的作用。结论由于具有良好的生物相容性和促进新骨生长的能力,生物玻璃/羟基磷灰石涂层可加快植入体与骨的愈合速度,在骨替代修复方面显示出优势和广阔的应用前景。     

生物活性玻璃/壳聚糖/羟基磷灰石复合骨修复材料制备及细胞相容性研究

目的设计一种生物活性玻璃/壳聚糖/羟基磷灰石(BG/HA/CS)复合材料的骨组织工程支架,并对其理化性能和细胞相容性进行检测。方法不同比例的BG/HA/CS混合液用冷冻干燥法制备成支架。通过计算支架孔隙率;扫描电镜、X线衍射和傅立叶红外光谱分析其微观形貌和组成;采用材料试验机进行支架的机械性能检测,并评价生物活性玻璃的加入对支架的影响。将第3代兔骨髓间充质干细胞接种于支架上,使用扫描电镜检测支架对其粘附作用,采用MTT法检测细胞在支架上增殖,并评价生物活性玻璃的加入对支架的细胞相容性影响。结果合成的BG/CS/HA支架与模具拥有同样的大小及几何形状,具有相互贯通的多孔结构,未见生物活性玻璃聚集,孔隙率最高可达86.96%,孔径大小合适(100~300um),最大压缩强度为(1.95±0.13)Mpa。X射线衍射图可以看到特征性的BG衍射峰;傅立叶变换红外光谱可见特征的BG吸收峰,这表明材料内有明确的BG;第3代兔骨髓间充质干细胞在支架上共培养1天后,细胞在支架表面粘附。部分细胞伸展,并伸出伪足。共培养5天后,可见细胞数目增多,团聚,细胞表面可见微绒毛,细胞已开始向材料内部迁移。采用MTT法测量骨髓间充质干细胞在支架上的增殖情况可以看出骨髓间充质干细胞在BG/CS/HA支架上表现出了明显的增殖。结论采用溶液共混、冷冻干燥法可以制备出BG/CS/HA支架;支架具有良好的孔隙率,较好的机械强度,良好的组织相容性,可用于骨组织工程。     

Bioactivity of three CaO-P2O5-SiO2 sol-gel glasses

Three gel glasses containing 25 mol % of CaO and SiO(2) + P(2)O(5) contents (in mol %): 75 + 0 (S75); 72.5 + 2.5 (S72.5P2.5); and 70 + 5 (S70P5), respectively, were obtained, characterized, and studied when soaked in a simulated body fluid (SBF). The influence of composition in both textural properties (surface area and porosity) and in vitro behavior of glasses was studied. In as prepared S72.5P2.5 and S70P5 glasses, crystalline phosphate nuclei were detected through XRD and FTIR. In addition, N(2) adsorption and Hg porosimetry measurements showed that the surface area increased, whereas the pore volume and the pore diameter decreased as P(2)O(5) in glasses increased. These variations were explained on the basis of the withdrawal of calcium from the glass silica network, due to the calcium-phosphorous bonding. In vitro studies showed that the three compositions were bioactive, because an apatite layer was formed after soaking in SBF. S75 presented the highest initial reactivity but the lowest crystallization rate of the apatite-like phase. For S72.5P2.5, and S70P5 the amorphous calcium phosphate formation was slower than for S75, but the crystallization of apatite was observed after shorter periods in SBF. Furthermore, after 7 days of soaking, the layer thickness decreased as P(2)O(5) in glasses increased.     

Calcium-phosphate metabolism parameters and erythrocyte Ca2+ concentration in autosomal dominant polycystic kidney disease patients with normal renal function

Introduction

The aim of this study was to assess calcium-phosphate metabolism of autosomal dominant polycystic kidney disease (ADPKD) patients with a special consideration to the following serum parameters: calcium (Ca²⁺), inorganic phosphate (Pi), parathyroid hormone (PTH) and intracellular erythrocyte calcium ([Ca²⁺]_i) concentrations.

Material and methods

The study included 49 adult ADPKD patients (19 males, 30 females) aged 36 ±11 years with normal renal function and no diagnosis of diabetes as well as 50 healthy controls (22 males, 28 females) matched for age and gender. Serum concentrations of sodium (Na⁺), potassium (K⁺) and magnesium (Mg²⁺) ions and Pi were determined with an indirect ion-selective method, while Ca2+ concentration was measured with a direct ion-selective method. The PTH was detected using a radioimmunometric method. [Ca²⁺]_i concentration was determined with the Ca²⁺ sensitive fluorescent dye Fura-2 method.

Results

In the ADPKD group, when compared to controls, the following concentrations were significantly higher: serum Ca²⁺ (1.18 ±0.06 mmol/l vs. 1.15 ±0.06 mmol/l, p = 0.0085), [Ca²⁺]_i (146.9 ±110.0 nmol/l vs. 96.5 ±52.7 nmol/l, p = 0.0075), serum Na+ (139.4 ±2.7 mmol/l vs. 138.5 ±2.1 mmol/l, p = 0.060, borderline significance), and PTH (15.5 ±6.8 pg/ml vs. 13.6 ±5.3 pg/ml, p = 0.066, borderline significance), while serum Mg²⁺ was significantly lower (0.81 ±0.09 mmol/l vs. 0.85 ±0.05 mmol/l, p = 0.021). In the ADPKD group we observed significant negative correlations of PTH with Ca²⁺ serum concentrations (Rs = –0.32, p = 0.025) and with estimated glomerular filtration rate (Rs = –0.31, p = 0.033).

Conclusions

The erythrocyte Ca²⁺ concentration is elevated in ADPKD patients with normal renal function. It may result from a dysfunction of mutated polycystins which can affect various aspects of electrolyte metabolism.     

Effect of ZnO addition on bioactive CaO-SiO2-P2O5-CaF2 glass-ceramics containing apatite and wollastonite

Some ceramics show bone-bonding ability, i.e. bioactivity. Apatite formation on ceramics is an essential condition to bring about direct bonding to living bone when implanted into bony defects. A controlled surface reaction of the ceramic is an important factor governing the bioactivity and biodegradation of the implanted ceramic. Among bioactive ceramics, glass-ceramic A-W containing apatite and wollastonite shows high bioactivity, as well as high mechanical strength. In this study, glass-ceramics containing zinc oxide were prepared by modification of the composition of the glass-ceramic A-W. Zinc oxide was selected to control the reactivity of the glass-ceramics since zinc is a trace element that shows stimulatory effects on bone formation. Glass-ceramics were prepared by heat treatment of glasses with the general composition: xZnOx(57.0-x)CaOx35.4SiO(2)x7.2P(2)O(5)x0.4CaF(2) (where x=0-14.2mol.%). Addition of ZnO increased the chemical durability of the glass-ceramics, resulting in a decrease in the rate of apatite formation in a simulated body fluid. On the other hand, the release of zinc from the glass-ceramics increased with increasing ZnO content. Addition of ZnO may provide bioactive CaO-SiO(2)-P(2)O(5)-CaF(2) glass-ceramics with the capacity for appropriate biodegradation, as well as enhancement of bone formation.     

Bone bonding behavior of MgO-CaO-SiO2-P2O5-CaF2 glass (mother glass of A.W-glass-ceramics)

In this study, it was found that a Ca-P layer and a Si layer were formed on the interface of the mother glass of apatite-wollastonite containing glass-ceramics (designated AW) and bone tissue. The dissolution of Si, Ca, and P from glass (MgO-CaO-SiO2-P2O5-CaF2) is necessary to form a chemical film (a Si layer and a Ca-P layer). The three kinds of glasses used were 1) a mirror surface of the mother glass (MgO 4.6, CaO 44.9, SiO2 34.2, P2O5 16.3, CaF 0.5 weight ratio) of AW (designated G-AW (mirror], 2) an abraded surface of G-AW (designated G-AW (#2000)), 3) a mirror surface SiO2 glass (designated G-Si, 100% SiO2). The glass plates (15 mm x 10 mm x 2 mm) were implanted into the metaphysis of tibia of mature male rabbits for 10 and 25 weeks. The failure load, when an implant detached from the bone or when the bone itself broke, was measured by a detaching test and the interface of glass/bone was observed by SEM-EPMA. Failure loads in G-Si, G-AW (mirror), and G-AW (#2000) 10 weeks after implantation were 0.18 +/- 0.24, 3.06 +/- 1.29, and 2.94 +/- 1.77 kg, respectively. Those in G-Si, G-AW (mirror), and G-AW (#2000) 25 weeks after implantation were 1.30 +/- 1.18, 3.88 +/- 1.06, and 3.55 +/- 1.51, respectively. The failure loads in G-Si vs. G-AW (mirror) and those in G-Si vs. G-AW (#2000) differed significantly (P less than 0.01). There were no significant differences in the failure load according to the surface roughness of G-AW. As shown by SEM-EPMA observation, a Si layer next to G was adjacent to a Ca-P layer next to the bone. The chemical film showed no increase in thickness as time passed. A Ca-P layer did not form on the interface of Si-G and bone.     

羟基磷灰石骨水泥中碳酸根存在的意义及其对溶解度的影响

目的探讨羟基磷灰石骨水泥中碳酸根存在的意义及其对溶解度产生的影响。方法制备碳酸化羟基磷灰石骨水泥，定量分析其固化产物晶体中的碳酸根结构。以磷酸钙骨水泥为对照组，分别预制直径为8mm、高为12mm的圆柱体试样。经模拟体液浸泡后，定期观察、测量每一试样的失重率，对照分析其体外溶解性的差别。结果碳酸化羟基磷灰石骨水泥固化产物的晶体中含有质量浓度5．6％的碳酸根，与自然骨的矿物成分更接近。随着时间的改变，材料在模拟体液中逐渐由白色转为微黄色，棱角逐渐变钝。体视显微镜下观察发现材料表面出现点、坑、片状溶蚀，碳酸化羟基磷灰石骨水泥较磷酸钙骨水泥更明显。失重率的检测表明，酸化羟基磷灰石骨水泥的失重率改变明显高于磷酸钙骨水泥。结论羟基磷灰石骨水泥中碳酸根的存在可增加其溶解度，加快降解速度。     

Strengthening of glass-ionomer cement by compounding short fibres with CaO-P2O5-SiO2-Al2O3 glass

The purpose of this study was to determine if short fibres of CaO-P2O5-SiO2-Al2O3 (CPSA) glass possessing a particular aspect ratio (length/diameter) could be used as a reinforcing agent for glass-ionomer cement. The powder of a commercial glass-ionomer cement (not resin modified) was mixed with variously sized CPSA glass short fibres before mixing with the liquid of the glass-ionomer cement. The mixed powders containing 60 mass% CPSA glass short fibres (diameter, 9.7 +/- 2.1 microm, aspect ratio, 5.0 +/- 0.9) obtained maximum values of 18 and 35 MPa for the diametral tensile strength (DTS) and flexural strength (FS) of set cements, respectively, after 24 h. These DTS and FS values were 1.8 and 4.5 times larger, respectively, than those of the set glass-ionomer cement not containing short fibres. Moreover, it was found that the addition of CPSA glass short fibres was remarkably more effective in the strengthening than electric glass (a typical glass fibre) short fibres. The results suggested that the CPSA glass short fibres acted as a reinforcing agent for strengthening the glass-ionomer cement, because of the shape of short fibres and reactivity between the mixing liquid and short fibres.     

In vitro structural changes in porous HA/β-TCP scaffolds in simulated body fluid

Porous scaffolds of biphasic calcium phosphate (hydroxyapatite/β-tricalcium phosphate (β-TCP)) have been fabricated and changes induced both in phase composition and porous architecture by immersion in simulated body fluid (SBF) under static and orbital stirring conditions have been studied. The starting porous scaffolds exhibit a low and randomized micro- and mesoporosity, an interconnected macroporosity centered at 100 and 0.6 μm, a fractal connectivity of D = 2.981 and total percent porosity of ca. 80%. After immersion for up to 60 days the micro- and mesoporosity increase slightly, which could be attributed to dissolution of the β-TCP phase confirmed by transmission electron microscopy. The effects of the change in the porous framework with SBF immersion time favor the bioactive behavior of the tested materials, inducing a nucleation and growth of a nanocrystalline apatite phase as the interconnected macroporosity centered at 0.6 μm is reduced. The macroporosity centered at 100 μm is still stable after 60 days in SBF. Therefore, these biphasic calcium phosphate porous scaffolds combine bioactive behavior with the stability of interconnected macroporosity over large periods of soaking time in SBF under static and orbital stirring conditions.     

Development and in vitro characterization of sol-gel derived CaO-P2O5-SiO2-ZnO bioglass

A CaO-P(2)O(5)-SiO(2)-ZnO bioglass was formed by the sol-gel technique and characterized by Raman spectroscopy, X-ray diffraction, energy dispersive X-ray analysis (EDXA) and scanning electron microscopy (SEM). The surface reactivity of the resultant glass-ceramic specimens was analyzed by immersion studies in simulated body fluid (SBF). SEM-EDXS and inductively coupled plasma atomic emission spectrometry techniques were used to monitor changes in the glass surface and SBF composition. Osteoblast cell culture experiments were performed to assess the biocompatibility and the alkaline phosphatase activity. Cell counts of the osteoblasts cultured on the bioglass samples were studied and compared with the polystyrene plates. The cells cultured on the bioglass disks consistently showed a higher alkaline phosphatase activity and cell counts compared to cells cultured on either polystyrene plates or the base CaO-P(2)O(5)-SiO(2) bioglass. This was due to cell proliferation and differentiation promoted by the zinc-substituted bioglass.     

Activiation of complement C3 by different calcium phosphate powders

The ability of different calcium phosphate to activate the complement system is studied by crossed immunoelectrophoresis demonstrating conversion of C3 to C3b. Complement consumption is determined by a haemolytic assay CH50. Hydroxyapatite powders after sintering induce a significant conversion of C3 and reduction of CH50 value. However the complement system is not activated by sintered tricalciumphosphate (β-whitlockite). This is not related to the adsorption behaviour it depends neither on chemical composition nor on crystal lattice. It is argued that C3 conversion is not triggered by the convertase of the classical pathway.     

The behaviour of apatite-based ceramics in relation to the critical 1150 degrees-1250 degrees C temperature range

Characterization of synthetic calcium phosphates is reported and compared with previous studies. Barium hydroxyapatite was also synthesized. Shrinkage on sintering, water absorption, tensile strength, porosity and X-ray diffraction patterns were studied. Hydroxyapatite and beta-tricalcium phosphate show compositional and mechanical property variation dependent on sintering temperatures. The property change on introduction of barium removes the practical value. X-ray diffraction analysis is considered essential before clinical use due to sensitivity of composition to sintering conditions.