多孔β-磷酸三钙支架材料的制备

采用泡沫浆料与三维凝胶叠层技术,成功制备了具有合适孔径和良好连通性的多孔β-磷酸三钙支架.研究了不同烧结温度和浆料固相含量对支架材料性能的影响.在优选的工艺参数下,所得到的多孔支架气孔率为72.9%～76.0%,抗压强度为4.9MPa～5.8MPa,其性能可以满足骨组织工程的需要.     

多孔钛骨组织工程支架设计及孔结构表征

针对目前骨组织工程支架微孔结构难以准确设计制备的问题,提出了一种基于点云的参数化建模+3D打印新方法。通过提取cube(C)、diamond(D)、gyroid(G)3种结构的型面函数点云数据,完成对不同孔结构特征的参数化建模。通过对模型有限元力学分析,对不同孔结构特征的多孔钛骨组织支架进行力学设计与订制。借助激光选区熔融(SLM)3D打印技术,完成对不同孔特征的骨组织支架快速成型。对多孔钛骨组织支架进行了相关材料学表征,包括孔结构表征与力学性能测试。结果表明:参数化模型的快速成型制造,能够有效地设计制备钛合金骨组织工程支架的孔结构特性,且可有效设计订制支架的力学性能,从仿生的角度实现多孔钛合金骨组织工程支架生物学功能的设计优化。     

钛合金变形Gyroid单元梯度多孔结构设计与分析

研究一种具有径向和轴向孔径梯度的变形Gyroid单元多孔结构参数化设计方法,采用激光选区熔化成形(selective laser melting, SLM)技术,制备出孔隙率为60%和75%的钛合金变形Gyroid单元梯度多孔结构样件。使用有限元法(finiteelementmethod,FEM)对4组梯度多孔支架模型及2组均质模型进行静力学仿真分析,对制备的钛合金梯度多孔样件进行力学性能测试,并与已测试过的均质样件进行力学性能对比分析。有限元计算结果与力学性能试验结果共同表明：变形Gyroid单元多孔结构力学性能随孔隙率的升高而降低,孔隙率相同时,径向梯度多孔支架力学性能优于均质多孔支架,更适用于皮质骨的骨缺损修复,轴向梯度多孔支架力学性能相比均质多孔支架有所减弱,更适用于松质骨。     

多孔金属激光增材制造研究进展

激光增材制造技术具有柔性化程度高、适应性强、材料利用率高、近净成形等特点,被广泛的应用于兼具功能和结构作用的多孔金属的制备。多孔金属激光增材制造技术按孔形成机制的不同可分为直接成孔法、添加造孔剂法以及结构设计成孔法。在介绍多孔金属激光增材制造国内外研究现状的基础上,指出各制备工艺的特点,并展望了多孔金属激光增材制造技术的发展趋势。     

激光选区融化成形多孔硬骨支架的建模、仿真及实验研究

金属3D打印技术成为当前最具有发展潜力和发展前景的工业制造技术之一,通过SLM激光选区烧结技术,选取合理的烧结参数,将金属粉末烧结成型。建立了不同孔径的多孔支架复杂三维模型,并通过有限元分析进行应力、应变的模拟分析,获得了优化后的多孔支架三维模型,为后续的实验研究分析建立理论基础,然后通过SLM烧结技术制备316L不锈钢多孔支架,通过后期热处理实验、压缩试验、金相实验,对多孔试样进行力学性能分析、硬度测试以及表面微观组织分析。通过模拟分析获得优化后的多孔支架孔径尺寸,获得了更适于人体骨骼缺损部位承重的多孔支架,可对后续研究进行指导。实验研究发现300μm孔径支架强度和弹性模量都高于天然骨,而成形多孔结构的金属件保证了骨骼修复体的生物力学性能,具有良好的力学性能。     

选择性激光熔化成形自生长多孔支架的建模与实验研究

3D打印技术制备医用生物多孔支架是目前最有前景和吸引力的生物医学应用之一。采用建模软件(C4D)通过随机域建立自生长多孔结构支架,最大程度地模拟松质骨的形态和结构。通过选择性激光熔化技术获得默认尺寸120%、160%、200%和240%比例的的三维结构模型。通过金相分析、热处理、硬度测试和压缩实验,对自生长多孔支架试样进行微观组织和力学性能分析。实验研究发现,自生长多孔支架在200%比例的孔径下,力学性能高于其它孔径比例的自生长多孔支架和天然骨。自生长多孔支架的表面形态和结构与人类松质骨相似,具备较高的细胞曲率驱动效应,有利于成骨细胞的富集,因此,具备更适合修复人体患病骨骼的可能性。     

生物活性多孔钽支架的构建及其初步生物学评价

表面生物活性涂层构建是提升金属内植物骨整合能力的有效途径,本研究利用电化学沉积技术在多孔钽支架表面构建生物活性羟基磷灰石(HA)涂层。通过接触角和比表面积测试发现,HA涂层的构建显著提升了多孔钽表面亲水性,并增加了其比表面积。利用模拟体液浸泡试验评估支架生物活性,发现仅浸泡3天后,多孔钽支架表面就已被类骨磷灰石沉积所覆盖。建成骨细胞培养模型,通过激光共聚焦观察及细胞增殖测试发现,所有支架均具有良好的细胞相容性。并且,细胞共培养5天后,HA涂层化多孔钽支架表面细胞的增殖率分别是未改性材料组和空白对照组的1.1和1.4倍,呈现了更大的促细胞增殖潜力。本研究中所制备的生物活性多孔钽支架具备快速诱导类骨磷灰石沉积能力,能够促进成骨细胞在其表面的贴附和增殖,在骨修复领域具有较大的临床应用前景。     

空间网格状多孔316不锈钢的选区激光熔化制备

制备出尺寸可控的空间网状金属多孔材料,对所制备的多孔材料进行组织分析.分析试样的微观结构,并讨论选区激光熔化多孔金属材料的成形机制及工艺参数对多孔结构特征的影响规律.结果表明:通过CAD制图确定扫描路径图,确定了骨架每根梁之间的扫描间距,决定了金属多孔材料的孔隙大小、孔隙形状及分布.制备出试件的每片薄壁、方孔分布均匀,孔隙大小统一且形状规则.骨架连接结点紧密,骨架的组织严密无开裂和弯曲现象.选区激光熔化制备空间网格状多孔材料骨架的形成机理分为颗粒表面局部熔化、形成金属熔池和粉末粘接三个阶段.     

心血管支架用Mg-Nd-Zn-Zr生物可降解镁合金的性能研究

以Mg-3.13Nd-0.16Zn-0.41Zr(质量分数,%,JDBM)镁合金为研究对象,研究挤压态JDBM的细胞毒性和腐蚀性能。通过热挤压工艺制备出心血管支架用镁合金微管,并观察其组织。采用激光切割、电化学抛光等工艺制备出心血管支架,测试支架表面粗糙度和径向支撑力。结果表明,JDBM镁合金对内皮细胞无毒性,具有理想的耐蚀性能和腐蚀方式;制备出的心血管支架的径向支撑力超过正常成年人血管收缩压的4倍,满足心血管支架对力学性能的要求。     

仿生非光滑耦合模具的耐磨损和热疲劳性能研究

采用激光仿生数控制备系统,在H13热锻模具表面进行仿生非光滑耦合处理,并研究了仿生非光滑耦合处理对模具表面硬度、耐磨损性能和热疲劳性能的影响。结果表明,适当的激光工艺参数可制备出网格状的仿生非光滑耦合单元体,单元体横截面为凸包状单元体结构;与未进行表面处理的H13钢热锻模具相比,仿生非光滑耦合处理使模具的表面平均硬度增加19%,800℃磨损体积减小81.7%;1000次20~800℃冷热循环后模具的主裂纹平均宽度减小91.2%,平均深度减小87.3%。     

Development of porous medical implant scaffolds via laser additive manufacturing

The objective was to develop and evaluate the porous medical implant scaffolds designed via digital method and fabricated by laser additive manufacturing. A porous artificial femur model and several vessel scaffolds with customized design were created based on the widely used computed tomography (CT) technology and Pro/Engineer software, and then were obtained by selective laser melting of powdered titanium-alloy material. The fabricating results show that supports are not required with the improvement of the processability of lattice, and porous scaffolds with good interconnectivity can be fabricated. Some issues also appear, such as the low geometric accuracy of lattices. The exploited design freedom is an expected benefit in medical field due to the individual characteristic of each patient. It is expected that more scaffolds will be developed and applied in practical fields with further study on design, process and biocompatibility.     

Fabrication of Bioceramic Bone Scaffolds for Tissue Engineering

In this study, microhydroxyapatite and nanosilica sol were used as the raw materials for fabrication of bioceramic bone scaffold using selective laser sintering technology in a self-developed 3D Printing apparatus. When the fluidity of ceramic slurry is matched with suitable laser processing parameters, a controlled pore size of porous bone scaffold can be fabricated under a lower laser energy. Results shown that the fabricated scaffolds have a bending strength of 14.1 MPa, a compressive strength of 24 MPa, a surface roughness of 725 nm, a pore size of 750 μm, an apparent porosity of 32%, and a optical density of 1.8. Results indicate that the mechanical strength of the scaffold can be improved after heat treatment at 1200 °C for 2 h, while simultaneously increasing surface roughness conducive to osteoprogenitor cell adhesion. MTT method and SEM observations confirmed that bone scaffolds fabricated under the optimal manufacturing process possess suitable biocompatibility and mechanical properties, allowing smooth adhesion and proliferation of osteoblast-like cells. Therefore, they have great potential for development in the field of tissue engineering.     

新型多孔镁压缩性能的有限元分析

利用有限元方法建立了激光打孔制备的直孔型多孔镁样品的压缩模型,系统分析了孔隙率、孔径及孔的排布对多孔镁样品压缩性能的影响,初步探讨了多孔镁在压缩过程中的变形规律.模拟计算结果表明,随着孔隙率、孔径的增加和孔的排布角的减小,多孔镁压缩曲线下移,屈服强度和弹性模量随之下降;多孔镁的压缩变形规律符合金属的最小阻力定律.     

Study on the designing rules and processability of porous structure based on selective laser melting (SLM)

Porous structures are widely used in medical implant, aerospace and other light-weight manufacturing fields. The research on processability and fabricating process are of great importance to laser addictive manufacturing of porous structure, therefore formulating several rules for SLM fabrication of porous structure is necessary. This article had studied the designing rules and the key points to fabricate the porous structure precisely based on selective laser melting (SLM). In order to obtain the fabricating effect of the pre-designed porous structure, besides optimizing fabricating process, there are still a few problems to be solved gradually, including the critical inclined angle, the fabricating resolution, powder adhesion, designing unit cell and porous structure that fit for SLM process. Through the experiments of fabricating overhanging structures with different inclined angles, the critical inclined angle for designing the porous structure was got. Through designing the thin walls and cylinders with different geometrical dimensions, the SLM fabricating resolution is obtained. Then, based on the critical inclined angle and the geometrical resolution, the octahedral unit cell structure and corresponding design rules that fitted for SLM process were proposed. At last, the experiment of fabricating porous structure was conducted and the pore's sizes were also measured. The results proved that the porous structure can be well fabricated by SLM. This study provides theoretical basis for designing and manufacturing of controllable porous structure based on SLM technique.     

Effect of porosity on mechanical properties of porous tantalum scaffolds produced by electron beam powder bed fusion

The effect of porosity on compressive, bending, and tensile properties of the porous tantalum scaffolds fabricated by electron beam powder bed fusion (EB-PBF) was investigated. The porous tantalum scaffolds with porosity from 69% to 77.8% were obtained by varying the designed porosity and adjusting the processing parameters. It is found that the pores and unfused powder decrease with the increase of deposited energy density. The decrease of porosity leads to an improvement in mechanical properties. The relevancy between compressive/bending/tensile yield strength and relative density can be described appropriately by exponential model, while the relationship between elastic modulus and relative density is in good agreement with the Gibson?Ashby model. All the porous tantalum scaffolds exhibit good ductility in compressive, bending and tensile tests. No fragmentation of struts is observed during the compression process, but cracks are formed on the strut surface after 90° bending, mainly due to the high sensibility to defects caused by the oxide.     

金属生物材料支架的微结构拓扑优化设计及选区激光熔化制造(英文)

生物材料支架的精确设计和制造是骨组织工程系统研究的基础。生物材料支架应该同时满足大孔隙率和与骨组织匹配的力学性能要求。这两个目标相互制约,大的孔隙率会降低其力学性能。利用拓扑优化的方法,在体积分数的约束下,寻求刚度最大的最优材料分布微结构。建立算法,得到了不同体积分数的2D和3D最优微结构,并提取3D拓扑优化的结果,然后将其转化为STL格式的CAD模型文件。微结构在三维方向整列成支架结构,通过选区激光熔化方法制造30%(体积分数)的Ti支架样品。从SEM图像看出,支架样品的结构和孔径与CAD模型基本一致,500μm微结构单元的平均孔径为231μm。复杂形状金属生物材料支架的精确制造证实了选区激光熔化技术在金属生物医学材料制造中的可行性。     

不同类型多孔结构生物材料支架制备及其性能优化

多孔支架是组织工程应用中的关键环节,类似细胞外基质的作用,支撑细胞的粘附和随后细胞向组织的衍化。虽然目前已采用多种制备技术研发出大量的多孔支架,但是多孔生物材料支架的制备和性能优化,仍然是组织工程支架领域的研究热点。结合实验室工作,综述了多种制备不同类型多孔结构生物材料支架的制备技术,主要包括颗粒和纤维堆积型支架、泡沫浸渍法支架和颗粒制孔支架等的制备技术,并阐述了这些制备技术对多孔结构支架的孔结构、贯通性和力学性能的改善效果。其目的旨在提供满足组织工程需求的多孔生物材料支架。     

钽涂层多孔钛合金支架的制备与表征

钽金属是一种理想的医用金属材料,能够与人体软/硬组织发生整合。利用化学气相沉积方法,在可控多孔结构的Ti6Al4V合金支架表面沉积涂覆钽金属涂层,使其同时具备理想的三维孔隙结构和力学相容性,以及钽金属优异的生物学性能。研究结果显示,多孔钛合金支架表面涂层前后色泽发生明显变化,涂层后支架呈现钽金属色泽。扫描电镜和XRD分析进一步证明了多孔钛合金支架表面沉积物为钽金属。与美国Zimmer公司生产的多孔钽小梁金属相比,钽涂层多孔钛合金支架具备与人体皮质骨更相似的弹性模量和抗压强度,是一种理想的骨修复替代物。     

Mechanical properties of AM Ti6Al4V porous scaffolds with various cell structures

Porous scaffolds as succedaneum of natural bone were investigated and applied in medical field.In this work, we carried out studies on mechanical properties of solid parts and porous scaffolds obtained by additive manufacturing(AM) technique.It is found that productions of AM process have a higher yield strength and higher microhardness compared to commercial Ti6Al4V.Roughened surface was observed for layer-by-layer process of AM and sticking of powder particles.The machining accuracy is affected by both dimensions and angles.Meanwhile, mechanical properties of porous scaffolds are influenced by machining accuracy and microdefects.In addition, the unit cell structures also impact the mechanical properties of porous scaffolds in terms of elastic modulus, yield strength and failure mode.Overall,considering the mechanical properties and biological properties, scaffolds with cube(CB) crystal cells are the best choice in our study.     

Three-dimensional chitosan-nanohydroxyapatite composite scaffolds for bone tissue engineering

We describe the structure of biodegradable chitosan-nanohydroxyapatite (nHA) composites scaffolds and their interaction with pre-osteoblasts for bone tissue engineering. The scaffolds were fabricated via freezing and lyophilization. The nanocomposite scaffolds were characterized by a highly porous structure and pore size of ∼50–125 μm, irrespective of nHA content. The observed significant enhancement in the biological response of pre-osteoblast on nanocomposite scaffolds expressed in terms of cell attachment, proliferation, and widespread morphology in relation to pure chitosan points toward their potential use as scaffold material for bone regeneration.