HA（＋ZrO2＋Y2O3）／Ti6Al4V复合涂层的微结构与生物活性

采用射频磁控溅射法成功制备了HA（＋ZrO2＋Y2O3）／Ti6Al4V生物复合涂层。借助于XRD、SEM、FTIR及AFM等对溅射涂层的相组成、微观形貌和界面结合进行了研究，并以模拟体液试验探讨了涂层的生物活性。实验结果表明：磁控溅射的复合涂层呈非晶态，经过退火处理，可以使其完全转化为晶态；复合涂层的微观表面凹凸不平，并呈现网状结构和较多的孔隙，其孔隙直径约为0．5μm-2μm；涂层的生长模式为层状加岛状生长；复合涂层在模拟体液中浸泡一段时间后，表面覆盖一层新生物质——含有CO^2-3的类骨磷灰石，其晶粒非常小，它与自然骨中无机相的结构成份相似．因此复合涂层具有良好生物相容性和生物活性。     

Ti基生物医用材料表面K2Ti6O13涂层的制备与表征

目的 新型表面改性技术和改性材料的开发是当今生物医学材料研究的主要方向，羟基磷灰石(HA)是一种最重要的表面改性材料，但较高的脆性和较低的结合强度严重制约了它在临床中的应用。方法本研究首次选用K，Ti6O13作为生物医用Ti合金的表面改件材料，利用KDC法尝试制备了K2Ti6O13涂层，并对涂层的微结构、结合强度和生物活性进行了观察分析与评估。结果利用KDC方法可以成功地原位合成K2Ti6O13涂层，涂层与钛合金基体间结合牢固，结合强度可达24MPa，热膨胀系数的良好匹配是结合强度提高的主要原因。结论涂层粗糙的表面和气孔可为骨的向内生长提供有利位置。经模拟体液浸泡，涂层表面形成了钙磷比接近人体骨骼的钙磷层，表明涂层具有良好的生物活性。     

HA(+ZrO2+Y2O3)/Ti6A14V复合涂层的微结构与生物活性

采用射频磁控溅射法成功制备了HA(+ZrO2+Y3O3)/Ti6A14V生物复合涂层.借助于XRD、SEM、FTIR及AFM等对溅射涂层的相组成、微观形貌和界面结合进行了研究,并以模拟体液试验探讨了涂层的生物活性.实验结果表明磁控溅射的复合涂层呈非晶态,经过退火处理,可以使其完全转化为晶态;复合涂层的微观表面凹凸不平,并呈现网状结构和较多的孔隙,其孔隙直径约为0.5 μm～2 μm;涂层的生长模式为层状加岛状生长;复合涂层在模拟体液中浸泡一段时间后,表面覆盖一层新生物质--含有CO32-的类骨磷灰石,其晶粒非常小,它与自然骨中无机相的结构成份相似,因此复合涂层具有良好生物相容性和生物活性.     

用磁控溅射技术制备钛合金表面HA生物涂层

目的 探讨磁控溅射法制备的HA生物涂层组织结构以及涂层与基体的界面结合性能。方法 利用射频磁控溅射技术在Ti-6Al-4v基体表面制备HA生物涂层，利用扫描电镜(SEM)观察HA生物涂层表面形貌和断面形貌，利用X射线衍射仪(XRD)分析涂层的相结构，利用能量分散谱仪(EDS)分析涂层的Ca／P比，采用环氧树脂E-7对接法测定HA涂层与基体的界面结合强度。结果 溅射HA生物涂层的Ca／P比为1．7，后处理生物涂层中不存在其它钙磷杂质相，HA的晶化程度高，HA涂层与基体的界面结合强度为51．2MPa。结论 射频磁控溅射技术制备的HA生物涂层，表面形貌良好，涂层与基体的界面结合强度较高。     

C/C复合材料表面等离子喷涂HA涂层在SBF中的试验

目的 探讨不同模拟体液对HA涂层体外生物学行为的影响。方法采用等离子体喷涂法,在碳／碳复合材料表面制备HA涂层,并对涂层进行了热处理。利用X射线衍射仪(X-ray diffraction)、扫描电子显微镜(Scanning electron microscopy)等检测手段,分析该涂层的物相和形貌,观察HA涂层在模拟体液中的影响。结果XRD检测结果表明,在模拟体液浸泡过程中,涂层的主要组成相的相对含量和结晶度不断发生变化。由SEM分析结果可知,在浸泡过程中,内送粉方式下制得的HA涂层的表面沉积物呈现近似网状的结构。同时,在Ringer溶液中,可以观察到HA涂层溶解痕迹。结论通过适当的热处理可以恢复HA的结构完整性,同时提高涂层的结晶度。     

新型钛基溶胶凝胶涂层的细胞相容性研究

目的 通过对涂层的表面结构及其细胞相容性的研究,对新型的钛基溶胶凝胶HA涂层技术进行评价.方法 在纯钛材料表面制备新型的溶胶凝胶HA涂层,采用SEM对涂层表面特征进行测试.体外成骨细胞(MC-3T3)培养测试涂层的细胞相容性,并将钛基HA溶胶凝胶涂层的细胞相容性与传统的钛基等离子喷涂HA涂层做比较.结果 经过水热处理的钛基涂层表面为均一的晶体颗粒表面,细胞学实验发现与等离子HA涂层相比较,水热处理溶胶凝胶表面增强了细胞粘附作用,具有较好的成骨细胞粘附(P＜0.05).结论 本实验结果提示这种新型的水热处理钛基HA溶胶凝胶表面具有良好的成骨细胞粘附特性,因而有待于作进一步研究.     

HAF/YSZ梯度复合涂层的制备及结构和性能

背景：在钛合金基体表面制备涂层的方法多为等离子喷涂法、溶胶-凝胶法、离子束溅射法等,所制备的涂层性能不稳定、成分单一,且涂层物相组成较难控制。 目的：采用射频磁控溅射技术在Ti6Al4V基体上制备含氟羟基磷灰石梯度复合涂层HAF/YSZ。 方法：在Ti6Al4V基体上以射频磁控溅射技术制备含氟羟基磷灰石梯度复合涂层HAF/YSZ,利用X射线光电子能谱、扫描电镜等对涂层的成分分布、形貌、界面结合进行表征。通过模拟体液实验分析和评价HAF/YSZ涂层、HAF1.2涂层及羟基磷灰石涂层的生物性能。 结果与结论：所制备的HAF/YSZ梯度涂层表面粗糙,呈多孔岛状结构,有利于新生骨组织生长;涂层与基体结合紧密,各层间相互扩散,整体一致性较好;经模拟体液浸泡后,涂层表面有新生物质沉积,表现出较好的生物活性及稳定性,且梯度复合涂层较氟含量单一的氟羟基磷灰石涂层具有更好的抗体液溶解能力及稳定性。     

磁控溅射制备HA/Ti6Al4V复合材料种植体体外生物活性研究

研究了射频磁控溅射法制备的HA/Ti6Al4V复合材料种植体在模拟体液(Simulated body fluid,SBF)环境下的生物活性。利用扫描电镜(SEM)、能谱分析(EDS)、红外光谱(FTIR)及X-射线衍射(XRD)分析了该种植体涂层在模拟体液中浸泡前后的表面形貌、界面结合状态、晶体结构和相组成的变化,结果表明:该种植体涂层在模拟体液中存在溶解和新生物质在其表面沉积相伴的过程。其中,HA涂层表面的新生物质是一种缺钙型且含有CO32-的类骨磷灰石,其n(Ca)/n(P)比值约为1.56,晶粒小,结晶度低,接近于非晶态,这与自然骨中无机相的结构成分相似,因此具有良好生物相容性和生物活性。     

PMMA/HA-GF复合材料的体外实验研究

对以无机纤维(GF)增强聚甲基丙烯酸甲酯／羟基磷灰石(PMMA／HA)的复合材料(PDLLA／HA—GF)进行了材料表面结构形貌的观察和体外实验，包括材料的稳定性、体外细胞毒性试验、全身急性毒性试验、过敏试验、溶血试验等。实验结果表明：PMMA／HA-GF复合材料无毒、无过敏刺激性、不引起溶血，具有好的生物相容性。     

经羟基磷灰石涂层的外固定针与骨髓基质细胞生物相容性研究

目的探讨经羟基磷灰石(hydroxyapatite,HA)涂层的外固定材料与骨髓基质细胞(bone marrow stromal cell,BMSc)的生物相容性。方法通过经HA涂层的外固定材料与BMSc体外细胞培养实验,进行细胞形态学观察和细胞增殖、碱性磷酸酶活性测定。结果扫描电镜观察:较空白组和对照组,实验组细胞在涂层表面细胞贴附良好,细胞伸出较多伪足;细胞生长良好;细胞增殖,第5,8,12天有显著差异(<0.05);ALP活性,第6天试验组间有显著性差异(<0.05)。该生物材料对BMSc增殖、分化及分泌功能无抑制作用。结论经HA涂层的外固定材料具有良好的生物相容性。     

Bond strength of plasma-sprayed hydroxyapatite/Ti composite coatings

One of the most important clinical applications of hydroxyapatite (HA) is as a coating on metal implants, especially plasma-sprayed HA coating applied on Ti alloy substrate. However, the poor bonding strength between HA and Ti alloy has been of concern to orthopedists. In this paper, an attempt has been made to enhance the bonding strength of HA coating by forming a composite coating with Ti. The bioactivity of the coating has also been studied. HA/Ti composite coatings were prepared via atmospheric plasma spraying on Ti-6Al-4V alloy substrates. The bond strength evaluation of HA/Ti composite coatings was performed according to ASTM C-633 test method. X-ray diffractometer and scanning electron microscopy were applied to identify the phases and the morphologies of the coatings. The bioactivity of HA/Ti composite coating was qualified by immersion of coating in simulated body fluid (SBF). The obtained results revealed that the addition of Ti to HA improved the bonding strength of coating significantly. In the SBF test, the coating surface was covered by carbonate-apatite, which was testified by X-ray photoelectron spectroscope, indicating good bioactivity for HA/Ti composite coating. The bioactivity of the coating has not been reduced by the addition of Ti.     

In vitro studies of plasma-sprayed hydroxyapatite/Ti-6Al-4V composite coatings in simulated body fluid (SBF)

The bioactivity of plasma-sprayed hydroxyapatite (HA)/Ti-6Al-4V composite coatings was studied by soaking the coatings in simulated body fluid (SBF) for up to 8 weeks. This investigation was aimed at elucidating the biological behaviour of plasma-sprayed HA/Ti-6Al-4V composite coatings by analyzing the changes in chemistry, and crystallinity of the composite coating in a body-analogous solution. Phase composition, microstructure and calcium ion concentration were analyzed before, and after immersion. The mechanical properties, such as tensile bond strength, microhardness and Young's modulus were appropriately measured. Results demonstrated that the tensile bond strength of the composite coating was significantly higher than that of pure HA coatings even after soaking in the SBF solution over an 8-weeks period. Dissolution of Ca-P phases in SBF was evident after 24h of soaking, and, a layer of carbonate-apatite covered the coating surface after 2 weeks of immersion. The mechanical properties were found to diminish with soaking duration. However, slight variation in mechanical properties was found after supersaturation of the calcium ions was attained with the precipitation of the calcium phosphate layers.     

Bioactive hydroxyapatite coatings on polymer composites for orthopedic implants

Hydroxyapatite [HA, Ca10(PO4)6(OH)2] coatings on polymer composite substrates were investigated for their bioactivity and their physicochemical and mechanical characteristics. HA holds key characteristics for use in orthopedic applications, such as for coating of the femoral stem in a hip replacement device. The plasma-spray technique was used to project HA onto a carbon fiber/polyamide 12 composite substrate. The resulting HA coatings exhibited mechanical adhesion as high as 23 MPa, depending on the surface treatment of the composite substrate. The purpose of this investigation was to evaluate the bioactivity of an HA-coated composite substrate. HA- coated samples have been immersed in simulated body fluid (SBF) and maintained within a shaker bath for periods of 1, 7, 14, 21, and 28 days at 37 degrees C. Scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction techniques were performed on the samples before and after immersion into SBF. SBF was analyzed using inductively coupled plasma atomic emission spectrometry for element concentration and evaluation of the solution's purity. SBF conditioning led to the deposition of crystalline HA onto the surface of the coatings. The calcium-to-phosphorous ratios of initial HA coating and of newly deposited HA were respectively 1.72 and 1.65, close to the HA theoretical calcium/phosphorous value of 1.67. Results demonstrated that bioactive HA coatings were produced by plasma spraying, because SBF conditioning induced newly formed HA with high crystallinity. Mechanical adhesion of the HA coatings was not significantly affected upon SBF conditioning.     

Activity of plasma sprayed yttria stabilized zirconia reinforced hydroxyapatite/Ti-6Al-4V composite coatings in simulated body fluid

Hydroxyapatite (HA)/yttria stabilized zirconia/Ti-6Al-4V bio-composite coatings deposited onto Ti-6Al-4V substrate through a plasma spray technique were immersed in simulated body fluid (SBF) to investigate their behavior in vitro. Surface morphologies and structural changes in the coatings were analyzed by scanning electron microscopy, thin-film X-ray diffractometer, and X-ray photoelectron spectroscopy. The tensile bond strength of the coatings after immersion was also conducted through the ASTM C-633 standard for thermal sprayed coatings. Results showed that carbonate-containing hydroxyapatite (CHA) layer formed on the surface of composite coatings after 4 weeks immersion in SBF solution, indicating the composite coating possessed excellent bioactivity. The mechanical properties were found to decrease with immersion duration of maximum 56 days. However, minimal variation in mechanical properties was found subsequent to achieving supersaturation of the calcium ions, which was attained with the precipitation of the calcium phosphate layers. The mechanical properties of the composite coating were found to be significantly higher than those of pure HA coatings even after immersion in the SBF solution, indicating the enhanced mechanical properties of the composite coatings.     

In vivo study on biocompatibility and bonding strength of hydroxyapatite-20vol%Ti composite with bone tissues in the rabbit

Biocompatibility and bonding strength of hydroxyapatite-20vol%Ti composite fabricated by hot-pressing technique with bone tissues in the rabbit were investigated by in vivo studies in comparison with those of Ti metal and dense HA ceramic. Although fibrous tissues formed at the interface between the composite and bone tissues at 3 weeks in vivo, bonding strength of the composite increases faster than that of dense HA after 4 weeks. At 3 months in vivo, bonding strength of the composite is higher than that of dense HA and exceeds 6.5 MPa. Moreover, as compared with the visible bonding interfaces between dense HA and new bones, the bonding interfaces for the composite cannot already be distinguished and the composite was osseointegrated fully with bone tissues into one bony body. The shear fracture of bonding strength test for the composite occurred in new bone zones near the interface, which indicates that bonding strength of the composite could even exceed the shear strength of new bones after 3 months in vivo. In conclusion, HA-Ti composite has better osteoconduction and osseointegration abilities than Ti metal and dense HA ceramic after 3 months in vivo and is a promising biomaterial for hard tissue replacement.     

Development and in vitro characterisation of novel bioresorbable and bioactive composite materials based on polylactide foams and Bioglass for tissue engineering applications

Bioactive and bioresorbable composite materials were fabricated using macroporous poly(DL-lactide) (PDLLA) foams coated with and impregnated by bioactive glass (Bioglass) particles. Stable and homogeneous Bioglass coatings on the surface of PDLLA foams as well as infiltration of Bioglass particles throughout the porous network were achieved using a slurry-dipping technique in conjunction with pre-treatment of the foams in ethanol. The quality of the bioactive glass coatings was reproducible in terms of thickness and microstructure. Additionally, electrophoretic deposition was investigated as an alternative method for the fabrication of PDLLA foam/Bioglass composite materials. In vitro studies in simulated body fluid (SBF) were performed to study the formation of hydroxyapatite (HA) on the surface of PDLLA/Bioglass composites. SEM analysis showed that the HA layer thickness rapidly increased with increasing time in SBF. The high bioactivity of the PDLLA foam/Bioglass composites indicates the potential of the materials for use as bioactive, resorbable scaffolds in bone tissue engineering.     

Comparison of plasma-sprayed hydroxyapatite coatings and zirconia-reinforced hydroxyapatite composite coatings: in vivo study

The clinical use of plasma-sprayed hydroxyapatite (HA) coatings on metal implants has been widely adopted because the HA coating can achieve the firmly and directly biological fixation with the surrounding bone tissue. However, the long-term mechanical properties of HA coatings has been concern for the long-term clinical application. Previous research showed that the concept of adding ZrO2 as second phase to HA significantly increased the bonding strength of plasma-sprayed composite material. The present work aimed to explore the biological properties, including the histological responses and shear strength, between the plasma-sprayed HA and HA/ZrO2 coating, using the transcortical implant model in the femora of canines. After 6 and 12 weeks of implantation, the HA coating revealed the direct bone-to-coating contact by the backscattered electron images (BEIs) of scanning electron microscope (SEM), but the osseointegration was not observed at the surface of HA/ZrO2 coating. For new bone healing index (NBHI) and apposition index (AI), the values for HA implants were significantly higher than that for HA/ZrO2 coatings throughout all implant periods. After push-out test, the shear strength of HA-coated implants were statistically higher than HA/ZrO2 coated implants at 6- and 12-week implantation, and the failure mode of HA/ZrO2 coating was observed at the coating-bone interface by SEM. The results indicate that the firm fixation between bone and HA/ZrO2 has not been achieved even after 12-week implantation. Consequently, the addition of ZrO2 could improve the mechanical properties of coatings, while the biocompatibility was influenced by the different material characteristics of HA/ZrO2 coating compared to HA coatings.     

In vitro stability of plasma-sprayed hydroxyapatite coatings on Ti-6Al-4V implants under cyclic loading

The success of hydroxyapatite (HA)-coated Ti-6Al-4V implants relies on the long-term stability of HA coatings. In this study, the mechanical stability of plasma-sprayed HA coatings on Ti-6Al-4V implants under four-point cyclic bending was systematically investigated in both air and simulated body fluid (SBF) environments at room temperature. To have a clear view of the microscale damage evolution, the surface morphology change of HA coatings during cyclic loading was carefully examined by scanning electron microscopy at the same locations on the coating surfaces after four-point bending for 4, 6.5, 8.5, and 10 million cycles. Also, possible changes of other characteristics such as thickness, weight, crystallinity, and residual stress of HA coatings were measured as a function of loading cycles. Up to 10 million cycles of bending in air and SBF, we found no significant microcracking or coating spalling on the surface of coatings, and no significant changes in thickness, weight, crystallinity, or residual stress of the plasma-sprayed HA coatings. The experiment results indicate that thickness and crystallinity had no effects on the stability of the HA coatings. HA coating resistance to the cyclic four-point bending might result from the stress shielding effects of preexisting microcracks in the coatings.     

Bond strength determination of hydroxyapatite coatings on Ti-6Al-4V substrates using the LAser Shock Adhesion Test (LASAT)

An adhesion test procedure applied to plasma-sprayed hydroxyapatite (HA) coatings to measure the "LASAT threshold" (LAser Shock Adhesion test) is described. The good repeatability and minimal discrepancy of the laser-driven adhesion test data were ascertained for conventional plasma sprayed HA coatings. As a further demonstration, the procedure was applied to HA coatings with diverse characteristics on the ceramic/metal interface. Different preheating and grit blasting conditions and the presence of a thick plasma-sprayed Ti sublayer or a thin TiO(2) layer prepared by oxidation were investigated through LASAT. It was assessed that a rough surface can significantly improve the coating's bond strength. However, it was also demonstrated that a thin TiO(2) layer on a smooth Ti-6Al-4V substrate can have a major influence on adhesion as well. Preheating up to 270°C just prior to the first HA spraying pass had no effect on the adhesion strength. Further development of the procedure was done to achieve an in situ LASAT with in vitro conditions applied on HA coatings. To that end, different crystalline HA contents were soaked in simulated body fluid (SBF). Beyond the demonstration of the capability of this laser-driven adhesion test devoted to HA coatings in dry or liquid environment, the present study provided empirical information on pertinent processing characteristics that could strengthen or weaken the HA/Ti-6Al-4V bond.