射频磁控溅射法制备羟基磷灰石/β-磷酸三钙生物涂层

目的以粉末冶金烧成的羟基磷灰石(HA)/-β磷酸三钙(β-TCP)陶瓷为靶材,采用磁控溅射法在钛合金(Ti6Al4V)基体上制备HA/β-TCP生物涂层。方法利用XRD研究了复合涂层的晶化程度,讨论了涂层成分与生物降解性及相容性的关系。结果HA/β-TCP生物涂层为非晶态,经700℃,3h大气处理可显著提高涂层的晶化程度,当涂层成分为50wt%HA/50wt%β-TCP时其细胞相容性最好。结论在钛合金基体上制备HA/β-TCP生物涂层,通过HA与β-TCP的复合来控制材料的降解速度,使它的降解速度与周围骨组织的生长速度相匹配,使植入体具有良好的生物降解性、生物活性和力学性能。     

HA的含量对聚氨酯/HA复合材料性能的影响

采用凝胶法制备聚氨酯 /HA复合材料 ,研究 HA的含量对聚氨酯 /HA复合材料力学性能与降解性能的影响。结果表明 ,当 HA含量为 2 0 %～ 30 %时 ,材料具有良好的力学性能 ,通过改变 HA含量可以调节复合材料的降解性能     

Al_2O_3质人工髋关节的强度及其抗裂纹缓慢扩展特性

本文从力学性能的要求出发,研究和分析Al_2O_3陶瓷作为人工骨骼材料的可能性。实验表明,Al_2O_3陶瓷(含95～99％Al_2O_3)和刚玉质人工髋关节的张力强度分别为215～302和336～368MN/m~2;其断裂韧性分别为4.0～4.5和4.5MN/m3/2。人工关节Ⅱ-Al_2O_3和99-Al_2O_3陶瓷的伟布尔模数为9.5,而人工关节Ⅰ-Al_2O_3和97-Al_2O_3陶瓷的伟布尔模数为6.5。两种95-Al_2O_3(A和B)陶瓷的伟布尔模数皆达21,与添加剂无关。Al_2O_3质关节能承受活体骨骼所承受的负载和磨损作用。     

SrHA/PMMA复合骨水泥的制备、理化性能及细胞相容性研究

目的结合PMMA和锶羟基磷灰石(Sr HA)各自的优势,制备出兼具高的力学强度、合适的固化时间、较低的热释放、生物活性和骨整合性能的Sr HA/PMMA复合骨水泥,并系统性地研究Sr HA的引入对复合骨水泥的体外固化性能、力学强度和生物学性能的影响。方法将水热合成法制备的锶羟基磷灰石引入PMMA基体,制备Sr HA/PMMA复合骨水泥。系统性地对Sr HA/PMMA复合骨水泥的力学强度、固化时间、热释放、生物活性进行研究。将复合骨水泥和细胞共培养,利用MTT法、扫描电镜等研究Sr HA/PMMA复合骨水泥的细胞毒性,粘附和增殖。结果结果表明,与纯的PMMA骨水泥(对照组)相比,Sr HA/PMMA复合骨水泥的固化热释放明显降低(约80~84℃),同时又维持了合适的固化时间(8~11分钟)和较好的力学性能(抗压强度为90MPa左右)。Sr HA的引入,不仅赋予了复合骨水泥生物活性,也显著地改善了其细胞/材料的相互作用。浸泡在SBF后,Sr HA/PMMA复合骨水泥显示出更好的体外矿化性能。与成骨细胞MC3T3-E1共培养后,表面沉积的羟基磷灰石能够更好的促进细胞的粘附和爬行。结论兼具优异的理化性能和生物活性的Sr HA/PMMA复合骨水泥,有着广阔的骨科微创修复应用前景。     

α-磷酸三钙/HA晶须/羧甲基壳聚糖-明胶复合增强多孔骨水泥的制备研究

为研究羟基磷灰石(HA)晶须和羧甲基壳聚糖-明胶(CMC-Gel)对多孔磷酸钙骨水泥(CPC)力学性能的影响,将α-磷酸三钙(α-TCP)粉、HA晶须和致孔剂L-谷氨酸钠按一定的质量比进行混合,加入调和液制备成α-TCP/HA晶须复合多孔骨水泥,然后将其浸润到一系列不同CMC和Gel质量比的溶液中以制备α-TCP/HA晶须/CMC-Gel复合增强多孔骨水泥,对其进行抗压强度测试和扫描电镜观察。结果显示,当HA晶须含量为4%,未添加CMC和Gel时,α-TCP/HA晶须复合多孔骨水泥的抗压强度达到2.57MPa,与未复合HA晶须的骨水泥相比提高了81%;当CMC和Gel的质量比为50∶50时,α-TCP/HA晶须/CMC-Gel复合多孔骨水泥的抗压强度达到最大值3.34MPa,与单纯的多孔α-TCP骨水泥相比提高了135%,同时韧性也有较大改善。     

熔融共混制备PLLA/HA/α-Fe2O3复合界面螺钉的力学性能研究*

目的采用熔融共混及注塑成型工艺制得新型磁性界面螺钉聚左旋乳酸/羟基磷灰石/α-Fe_2O_3,(PLLA/HA/α-Fe_2O_3),并对PLLA/HA/α-Fe_2O_3,界面螺钉力学性能进行初步研究。方法运用注塑机制得2种界面螺钉PLLA/HA(24wt%)/α-Fe_2O_3,和PLLA/HA(4wt%)/α-Fe_2O_3。电子万能试验机对界面螺钉实施拉伸及弯曲试验,记录试验结果并进行统计学分析,并对材料断面进行扫描电子显微镜观察。结果PLLA/HA(4wt%)/α-Fe_2O_3,组在拉伸及弯曲试验中最大载荷和最大位移均高于PLLA/HA(24wt%)/α-Fe_2O_3,组(P0.05)。扫描电镜示螺钉断裂面粗糙、不平整,PLLA/HA(4wt%)/α-Fe_2O_3,中HA大致均匀分布于PLLA中,HA与PLLA界面结合紧密。结论熔融混合注塑成型工艺具有操作简单、利于加工成型及便于实施批量生产等优点,制备的界面螺钉PLLA/HA(4wt%)/α-Fe_2O_3,比PLLA/HA(24wt%)/α-Fe_2O_3,有更好的力学性能。     

溶胶-凝胶生物活性玻璃/胶原复合多孔支架的力学性能研究

目的研究溶胶-凝胶生物活性玻璃/胶原组织工程支架的力学性能及降解性能,为胶原基复合支架的进一步应用,提供理论基础。方法以纳米溶胶-凝胶生物活性玻璃为添加相,利用冷冻干燥法制备了4种溶胶-凝胶生物活性玻璃/胶原基复合多孔组织工程支架。结果(1)溶液中胶原纤维的聚集状态,制备出具有直径约为400～600nm的粗胶原纤维束支架材料,这种粗胶原纤维束对改善胶原基组织工程支架的力学强度和减慢其降解速度具有重要作用,其中胶原与生物活性玻璃质量比为40∶60时,具有最高的抗压强度(1.5469±0.0995)MPa。(2)利用FTIR和Raman等技术综合分析研究了溶胶-凝胶生物活性玻璃对胶原蛋白的二级结构的影响,当复合材料中胶原含量小于20%时,胶原蛋白二级结构破坏严重。结论当胶原与生物活性玻璃质量比为40∶60时,所制备的复合支架具有最好的抗压性能和降解性能,为进一步应用提供了研究基础。     

电沉积HA-Ti/HA复合涂层及其生物学性能

为了提高HA涂层的结合强度，采用两步电沉积法制备HA—Ti／HA复合涂层，对涂层的组分结构、表面形貌和结合强度进行了研究，并对涂层进行模拟体液和体外细胞实验，以考察涂层的生物学性能。实验结果表明：HA—Ti／HA复合涂层的结合强度明显高于HA涂层，当涂层中Ti的质量分数为51．2wt％时，涂层与基体的结合强度达到21．2MPa，约为纯HA涂层的3倍。涂层经模拟体液浸泡后，表面覆盖一层碳磷灰石（Carbonate—apatite），表明涂层具有良好的生物活性。体外细胞实验表明，骨髓基质细胞能在涂层表面黏附繁殖生长，表明涂层具有良好的生物相容性。     

羟基磷灰石复合骨组织工程支架的研究进展

近年来,以生物活性陶瓷、聚合物等材料为基础复合而成的人工骨骼材料得到了广泛的研究并取得了巨大的进展。纳米羟基磷灰石(nano Hydroxyapatite,n HA)因其具有良好的生物相容性和生物活性,被大量应用于骨组织的移植与修复,但由于现有工艺制备的磷灰石本身力学性能不够完美,进而限制了其应用的广泛性,因此,制备综合性能优越的纳米羟基磷灰石/聚合物复合生物材料是当今骨组织工程中研究的热点。在此,就纳米羟基磷灰石与壳聚糖、胶原、聚乳酸等高分子材料复合而成的新型骨移植替代材料的合成方法、力学性能和生物相容性进行简单的介绍。     

聚D,L-乳酸/羟基磷灰石复合纤维的力学性能研究

采用熔融纺丝法制备PDLLA／HA复合纤维，探讨PDLLA／HA复合纤维的力学性能及影响因素和性能变化规律。实验结果表明：在分子量为12万的PDLLA中，加入一定量4～20μm的HA颗粒能提高复合纤维的力学性能。在PDLLA基体中添加HA的质量分数以10％为宜，以此配比制备的复合纤维的断裂强度高于其它配比复合纤维的断裂强度。采用分子量为20～30万的PDLLA制备的复合纤维断裂强度高，性能优异。复合纤维断裂强度随纤维直径的增加而下降，在直径为40～60μm时，复合纤维断裂伸长率高，弹性好。     

Laminated and functionally graded hydroxyapatite/yttria stabilized tetragonal zirconia composites fabricated by spark plasma sintering

Hydroxyapatite (HA) ceramics have been conventionally strengthened and toughened in the form of composites and coatings. New microstructural designs and processing methodologies are still needed for the improvement of the mechanical properties of HA-based ceramics. This study was to prepare laminated and functionally graded HA/yttria stabilized tetragonal zirconia (Y-TZP) composites by the relatively new process of spark plasma sintering (SPS). The microstructure and the mechanical properties of the laminated and functionally graded composites were studied for possible orthopedic applications. It was found that the laminated and functionally graded HA/Y-TZP composites could be densified at 1200 degrees C within 5 min by the SPS process and the average HA grain size in the composite layers was reduced by half due to the well-dispersed Y-TZP second phase. The HA phase in the composite layers was stable up to 1200 degrees C and the Y-TZP second phase remained the tetragonal zirconia (t-ZrO(2)) phase after being processed at the highest temperature of 1250 degrees C. The laminated and functionally graded HA/Y-TZP composites exhibited much improved mechanical properties compared with the pure HA ceramics; the bending strength of the composites reached about 200 MPa, double the strength of the pure HA ceramics.     

Novel porous hydroxyapatite prepared by combining H2O2 foaming with PU sponge and modified with PLGA and bioactive glass

Porous hydroxyapatite (HA) scaffolds have been intensively studied and developed for bone tissue engineering, but their mechanical properties remain to be improved. The aim of this study is to prepare HA-based composite scaffolds that have a unique macroporous structure and special struts of a polymer/ceramic interpenetrating composite and a bioactive coating. A novel combination of a polyurethane (PU) foam method and a hydrogen peroxide (H(2)O( 2)) foaming method is used to fabricate the macroporous HA scaffolds. Micropores are present in the resulting porous HA ceramics after the unusual sintering of a common calcium phosphate cement and are infiltrated with the poly(D,L-lactic-co-glycolic acid) (PLGA) polymer. The internal surfaces of the macropores are further coated with a PLGA-bioactive glass composite coating. The porous composite scaffolds are characterized in terms of microstructure, mechanical properties, and bioactivity. It is found that the HA scaffolds fabricated by the combined method show high porosities of 61-65% and proper macropore sizes of 200-600 microm. The PLGA infiltration improved the compressive strengths of the scaffolds from 1.5-1.8 to 4.0-5.8 MPa. Furthermore, the bioactive glass-PLGA coating rendered a good bioactivity to the composites, evidenced by the formation of an apatite layer on the sample surfaces immersed in the simulated body fluid (SBF) for 5 days. The porous HA-based composites obtained from this study have suitable porous structures, proper mechanical properties, and a high bioactivity, and thus finds potential application as scaffolds for bone tissue engineering.     

Effects of hydroxyapatite additive content on the bioactivity and biomechanical compatibility of bioactive nano-titania ceramics

Bioactive nano-titania ceramics with excellent biomechanical compatibility and bioactivity were prepared by using hydroxyapatite (HA) additive as grain growth inhibitor with different contents. After sintered at 1000 degrees C with pressureless sintering method, the grain size of nano-titania ceramic was less than 70 nm. Mechanical test results showed that compressive strengths of the nano ceramics were from 137.5 to 275.6 MPa, elastic moduli from 7 to 8 GPa, and bending strengths from 38.67 to 111.96 MPa by increasing HA additive content from 1 to 20%. The mechanical properties of nano-titania ceramics were analogous to that of the human bone. The content of HA additive played an important role in adjusting the grain/particle size of nano-titania ceramics, which had a great effect on the osteoblasts proliferation in the cell culture experiments. The cell culture experiments also demonstrated that the bioactive HA additive itself also had a great effect on the cytocompatibility of the nano-titania ceramics. The results of the present study indicated that the content of HA additive not only had effect on the bioactivity of the nano-titania ceramics because of the bioactivity of the additive itself, but also had effect both on the biomechanical compatibility and bioactivity of the nano-titania ceramics by adjusting the grain/particle size of the ceramics.     

Correlations between the in vitro and in vivo bioactivity of the Ti/HA composites fabricated by a powder metallurgy method

Ti/HA composites were successfully prepared by a powder metallurgy method and the effect of phase composition on the in vitro and in vivo bioactivity of the Ti/HA composites was investigated in the present study. The correlations between the in vitro and in vivo biological behaviors were highlighted. The results showed that the in vitro and in vivo bioactivity of the Ti/HA composites was dependent on their phase composition. The in vitro bioactivity of the Ti/HA composites was evaluated in simulated body fluid with ion concentrations similar to those of human plasma. After immersion in the simulated body fluid for a certain time, apatite precipitations formed on the surface of the composites with an initial titanium content of 50 and 70 wt.%, and no apatite was found on the surface of the composite with 30% titanium. Ti(2)O was responsible for the apatite formation on the surfaces of the composites. For in vivo analysis, Ti/HA cylinders were implanted in the metaphases of the rabbit femur. At the early stage of implantation, the new bone formed on the surface of the composite with 30% titanium was much less than that on the surfaces of the composites with 50% and 70% titanium. All the Ti/HA composites formed a chemical bone-bonding interface with the host bone by 6 months after implantation. The Ti/HA composites formed the bone-bonding interface with the surrounding bone through an apatite layer. The results in the present study suggested that the in vivo results agreed well with the in vitro results.     

Hydroxyapatite-based composite for dental implants: an in vivo removal torque experiment

Screw-shaped dental implants were fabricated from commercially pure Ti (c.p. Ti) and HA-based composites. The HA-based composites were fabricated by mixing HA with Al(2)O(3)-coated ZrO(2) powders. The mechanical properties of these composites were enhanced by a factor of 3. These were implanted into the rabbit tibiae and the removal torque to loosen the implants in vivo was measured in order to investigate the osteointegration. After a healing period of 6 weeks, the implants were retrieved with a torque gauge instrument. The HA-based composite implants showed an almost 2-times-higher removal torque when compared to the Ti implants (ANOVA, p < 0.05), indicating excellent biocompatibility to bone. Thus, HA-based composites had not only better mechanical properties but also similar bioactivity as HA itself. It is believed that a HA-based composite is suitable for artificial dental implants.     

Hydroxyapatite nanoparticle loaded collagen fiber composites: microarchitecture and nanoindentation study

Hydroxyapatite (HA) nanoparticle-collagen composite materials with various HA/collagen weight ratios were prepared from HA/collagen dispersions using the solution deposition and electrospinning with static or rotating collectors. The composites with nanoparticle HA to collagen weight ratio of 80:20 can be easily prepared in the solution deposition approach, whereas in the electrospun fibrous composites it was possible to reach a maximum HA/collagen weight ratio of 30:70 while maintaining a good fibrous structure. The structure, surface morphology, and nanoindentation properties of these nanoparticle HA/collagen composites with different microarchitectures were investigated. The values from 0.2 GPa to 20 GPa for nanoindentation Young's modulus and from 25 MPa to 500 MPa for hardness, were obtained depending on the fabrication technique, composition, and microarchitecture of the composites. It was observed that the nanoindentation Young's modulus and hardness of the HA/collagen composite materials seem to achieve maximum values for 45-60% HA content by weight.     

Sol-gel preparation and in vitro test of fluorapatite/hydroxyapatite films

Fluorapatite/hydroxyapatite (FA/HA) films have been demonstrated to be a good alternative to pure hydroxyapatite (HA) ones in medical applications because of their bioactivity and relatively low solubility. In this study, Ca(NO(3))(2), P(2)O(5), and HPF(6) were used to prepare FA/HA films on Ti6Al4V substrate with the use of a sol-gel method. The F contents in the films could be tailored by adjusting the amount of HPF(6) added. The in vitro evaluation of the films was carried out in both SBF9# solution and TRIS buffer solution. The films with appropriate F contents showed a better ability to induce calcium phosphate deposition on their surfaces than either pure HA film and FA/HA films with even higher F content, as well as smaller dissolution amounts than HA film in TRIS buffer solution. Hence, the FA/HA films obtained in this work integrate both good bioactivity and stability, and could be a better choice for bioactive film on titanium alloys to produce high-quality implants.     

Push-out testing and histological evaluation of glass reinforced hydroxyapatite composites implanted in the tibia of rabbits.

In vitro and in vivo bioactivity studies were performed to assess the biocompatibility of CaO-P2O5 glass-reinforced hydroxyapatite (GR-HA) composites. The ability to form an apatite layer by soaking in simulated body fluid (SBF) was examined and surfaces were characterized using FTIR reflection and thin-film X-ray diffraction analyses. Qualitative histology, histomorphometric measurements, and push-out testing were performed in a rabbit model for characterizing bone/implant bonding. Under the in vitro conditions using SBF, an apatite layer could not be formed on GR-HA composites within 8 weeks. Results of push-out testing showed bonding between the composites and bone, ranging from 130-145 N after 2 weeks of implantation. After the longest implantation period, 16 weeks, the GR-HA composite prepared with the higher content of CaO-P2O5 glass showed the highest bonding force, 606 +/- 45 N, compared to 459 +/- 30 N for sintered HA. Development of immature bone and modifications in the turnover of a more mature bone on the surface of GR-HA composites were similar to those on sintered HA.     

Magnesia-doped HA/beta-TCP ceramics and evaluation of their biocompatibility

The sintering behavior, mechanical properties and biocompatibility of magnesia (MgO)-doped HA/TCP biphasic ceramics were studied. Pure HA/TCP ceramics showed poor sinterability due to the phase transformation of beta- to alpha-TCP. MgO-doped HA/TCP ceramics showed high density without any phase transformation of beta-TCP up to 1300 degrees C, for MgO dopants incorporated into the beta-TCP preferably and increased thermal stability of beta-TCP. However, the addition of MgO higher than a critical content, suppressed grain growth of HA/TCP ceramics and lowered sinterability. The optimum amount of MgO doping was 1 wt%, which lead 99% relative density and higher mechanical properties than HA or beta-TCP ceramics. From in vitro test and in vivo test, 1 wt% MgO-doped HA/TCP ceramics showed a good biocompatibility without cytotoxicity. After implantation under the muscle of rabbits, beta-TCP phase was dissolved from the surface and a biological apatite covered the surface. These results proved that MgO addition increased drastically the sintering and mechanical properties of HA/beta-TCP ceramics without altering the biological safety and biocompatibility of the original composite.