Interfacial and biological properties of the gradient coating on polyamide substrate for bone substitute

Fabrication of bioactive and mechanical matched bone substitutes is crucial for clinical application in bone defects repair. In this study, nano-hydroxyapatite/polyamide (nHA/PA) composite was coated on injection-moulded PA by a chemical corrosion and phase-inversion technique. The shear strength, gradient composition and pore structure of the bioactive coating were characterized. Osteoblast-like MG63 cells were cultured on pure PA and composite-coated PA samples. The cells'' adhesion, spread and proliferation were determined using MTT assay and microscopy. The results confirm that the samples with the nHA/PA composite coating have better cytocompatibility and have no negative effects on cells. To investigate the in vivo biocompatibility, both pure PA and composite-coated PA cylinders were implanted in the trochlea of rabbit femurs and studied histologically, and the bonding ability with bone were determined using push-out tests. The results show that composite-coated implants exhibit better biocompatibility and the shear strength of the composite-coated implants with host bone at 12 weeks can reach 3.49 ± 0.42 MPa, which is significantly higher than that of pure PA implants. These results indicate that composite-coated PA implants have excellent biocompatibility and bonding abilities with host bone and they have the potential to be applied in repair of bone defects.     

Sol-gel原位相转变矿化制备纳米羟基磷灰石/壳聚糖复合支架材料

为了模拟天然骨组织的结构和成分, 以羟基磷灰石(HA)为钙磷源, 以壳聚糖(CS)为大分子基质材料, 在酸性环境中形成均相溶液, 通过Sol-gel相转变矿化方法和陈化处理, 原位构建了纳米HA/CS复合多孔支架材料, 研究了共沉积时体系的pH值和陈化时间对支架压缩强度、晶相组成及形貌等的影响。结果表明体系pH为10和11时, 支架的力学强度远高于未矿化壳聚糖支架强度, 但是随着体系pH的升高强度逐渐下降。XRD分析结果表明陈化处理有利于磷酸钙盐向HA转化, 随着陈化时间的延长, 纳米HA沿c轴择优生长。SEM观察显示支架材料具有相互贯穿的多孔结构, 纳米级的短棒状或颗粒状HA晶体颗粒均匀分散在孔壁上, 随着陈化处理以及陈化时间的延长, 形成致密的纳米无机/有机均匀复合体。这种快速深度矿化方法为骨支架材料的制备提供了新思路。      

硅烷偶联剂对纳米羟基磷灰石表面改性的研究

采用硅烷偶联剂(KH-560)对纳米羟基磷灰石(n-HA)表面进行处理, 并研究了n-HA与KH-560的界面作用. 傅立叶红外光谱(FT-IR)以及X光电子能谱(XPS)分析表明, 偶联剂在羟基磷灰石表面黏附, 其中硅羟基(Si--OH)与磷酸氢根(HPO ^2-₄)基团之间脱水形成稳定的Si--O--P化学键, 此外, 硅羟基与HA表面--OH间亦脱水形成化学键合. 偶联处理的HA与聚碳酸酯(PC)复合后, 复合材料的力学强度与未经处理的相比有明显提高. 扫描电子显微镜(SEM)结果显示, 经处理后的HA微粒在PC中分散均匀, 两者间结合紧密, 表明无机有机复合材料间良好的界面作用是提高复合材料力学强度的重要途径.     

共滴定法制备纳米羟基磷灰石/甲壳素复合材料

以饱和氢氧化钙上清液、磷酸、甲壳素为主要原料,在37℃,PH值为9,反应时间6小时的条件下,采用共滴定法制备纳米级羟基磷灰石-甲壳素复合材料,并通过XRD、SEM、TEM、IR检测等测试手段对材料进行分析表征。结果表明:复合材料中的羟基磷灰石为类似于自然骨矿物相的弱结晶的含碳酸纳米晶体,粒径在40-100nm之间,均匀分散于有机相甲壳素中,纳米HAP有择优取向生长的迹象;复合后甲壳素的酰胺谱带向低波数方向发生移动,说明复合材料中两相间发生了某种相互作用。复合材料的真密度为3.06g/cm3。进行注射成型实验,在水料比为1.8ml/g时,材料适合注射成型。此复合材料可望成为较理想的骨修复材料。     

用超声分散法和研磨法制备纳米羟基磷灰石/聚酯型弹性体复合材料的比较

分别用超声分散法和研磨法制备了纳米羟基磷灰石(n-HA)/聚1,2-丙二醇-癸二酸-柠檬酸酯复合材料。通过差示扫描量热法、扫描电子显微镜和透射电子显微镜对复合材料中n-HA的分散性及复合材料的玻璃化转变温度进行了分析,测试了复合材料的溶胶含量、力学性能及降解性能。结果表明,无论是采用研磨法还是超声分散法制备的复合材料,其玻璃化转变温度和溶胶含量都随着n-HA质量分数的增加而降低,降解速率都随着n-HA质量分数的增加而减小。研磨法是改善n-HA在复合材料中的分散性、提高复合材料力学性能的有效方法。用该方法通过改变n-HA质量分数可使复合材料的拉伸强度提高8.2倍,弹性模量提高11.4倍,而扯断伸长率基本保持不变。     

纳米羟基磷灰石的预处理及在聚醚醚酮中的分散性

对纳米羟基磷灰石(n-HA)浆料进行了分析和纯化处理,研究了纯化处理后的n-HA在聚醚醚酮(PEEK)中的分散性,进而采用溶液共混法制备了一系列n-HA/PEEK复合材料。结果表明,n-HA原料(浆料)中含有的Ca、Na元素以及碳酸根可通过洗涤除去。XRD、FT-IR以及SEM等分析表明,添加硅烷偶联剂,以聚乙二醇作为分散剂,并采用超声振荡的方法能使n-HA均匀分散在聚醚醚酮(PEEK)中,其中的硅烷偶联剂与n-HA形成了新的键。     

纳米羟基磷灰石/壳聚糖复合微球的原位仿生制备及表征

为解决纳米羟基磷灰石/壳聚糖(nHA/CS)复合微球中nHA团聚及分散不均的问题, 本研究在油包水的乳液体系中, 原位仿生制备了nHA/CS复合微球, 并与共混法制备的nHA/CS复合微球进行了对比研究。利用扫描电镜(SEM)、X射线能谱(EDS)、X射线衍射(XRD)、红外(FTIR)和激光粒度仪等手段对不同微球的理化性能进行表征。结果表明: 相比共混法, 原位仿生制备的nHA/CS复合微球形态圆整均匀, 分散性好, 粒径分布较窄, 平均粒径为8.62 μm, nHA晶体均匀分布在微球内部及表面, 并与CS基质以化学键结合。该复合微球有望用于骨组织工程及药物控制释放。     

Microstructure and phase composition of Ti-based biocomposites with different contents of nano-hydroxyapatite

Nano-hydroxyapatite （nHA） and titanium （Ti） powders with different ratios were prepared by mechanical ball milling, and then sintered in vacuum environment. The microstructure and phase composition of Ti-based biocomposites with different contents of nHA（5% and 10%, in volume fraction） were investigated. Meanwhile, the phase composition of pure Ti was studied for contrast. The results show that Ti phase forms a finer continuous network microstructure with few porous after milling and sintering. The higher amount of nHA powders are added, the higher amount of porous are achieved, while the fracture morphology becomes coarser. The specimen with contents of 10% nHA has serious interface reaction after sintering at 1100 ℃, it varies with the pure Ti specimen. Combined with the XRD and EDS analysis, it can be founded that elements Ca, P, O and Ti diffuse on the interface, and the phases of Ti, Ti2o, Ti5P3, CaTiO3 and TiOx can be ascertained in nHA/Ti composites.