HA/PDLLA复合材料的制备及其降解性能研究

首先采用开环聚合合成了PDLLA, 液相-沉淀法合成了HA超微粉, 然后采用液相吸附法制备了HA/PDLLA复合材料. 以纯PDLLA进行对照, 对HA/PDLLA复合材料进行体外降解实验和体内植入实验, 并进行扫描电镜观察. 结果表明HA/PDLLA复合材料较单纯PDLLA材料的降解速度减慢, 机械强度升高, 避免了过早的丧失力学强度. HA颗粒从材料表面脱落后, 成纤维细胞向组织内长入, 并伴有少量新生骨痂的形成, 显示HA/PDLLA复合材料具有良好的降解性能, 一定的成骨性和骨连接性. 24周时, HA/PDLLA材料被组织分隔包裹, 新生骨组织长入材料, 骨愈合情况良好, 具有足够的强度保证实验性松质骨骨折正常愈合.     

亲水性聚氨酯复合材料的体外降解性和细胞相容性

采用摇床法和体外细胞培养法对亲水性羟基磷灰石/聚氨酯(HA/PU)纳米复合材料的体外降解性和体外细胞相容性进行了评估。结果表明:HA/PU纳米复合材料在磷酸缓冲溶液中浸泡不同时间后,材料发生了不同程度的降解。纳米HA含量对复合材料的降解性有一定影响,纳米HA含量较高的复合材料表现出较缓的降解速率。体外细胞相容性实验表明,MG63细胞在纯PU上成球型,抱团生长;而MG63细胞在HA/PU复合材料上生长良好,牢固地黏附在表面,并借助伪足在材料表面充分伸展,这说明HA/PU复合材料为细胞的黏附、增殖以及生存活力的维持提供了有利的环境。这些结果表明该HA/PU纳米复合材料有望用于骨组织工程修复。     

PLGA/HA骨支架材料的降解特性

采用有机泡沫法获得了HA多孔骨架.运用溶胶浇铸法将PLGA溶胶填充入多孔骨架中,制备出骨组织工程用PLGA/HA复合支架材料,并考察了其在模拟体液中的降解性能,通过SEM观察了其表面组织形貌.结果表明,随浆料中HA含量的增加,材料降解后质量损失增大,且随降解时间的延长,PLGA/HA骨支架材料表面粘附的磷灰石相增多,表明该复合材料具有良好的生物活性.     

新型可降解硫酸钙/聚酰胺复合材料的制备和表征

以6-氨基己酸(6-aminohexanoic acid,N6)和丁内酰胺(又名α-吡咯烷酮,α-pyrrolidone,α-P)为原料,通过6-氨基己酸熔融缩聚使丁内酰胺开环制备了一系列新型聚酰胺,优化选取6-氨基己酸与丁内酰胺摩尔比为7∶3的聚合物作为基体与硫酸钙(CS)复合,制备了新型可降解硫酸钙/聚酰胺复合材料。通过乌氏粘度计、万能力学实验机、红外光谱(IR)、差示扫描量热分析(DSC)、X射线衍射(XRD)和X光电子能谱(XPS)对其特性黏数、抗压强度及组成与结构进行了表征,并研究了复合材料在磷酸缓冲溶液(PBS)的体外降解性能。结果表明产物为具有酰胺键结构的聚合物,6-氨基己酸与丁内酰胺摩尔比为7∶3时聚合物既能最大程度地引入丁内酰胺又具有较好的力学性能。复合材料无机相与有机相之间存在化学键作用。体外降解实验表明本文合成的聚酰胺是可降解的;相比于聚合物,硫酸钙/聚酰胺复合材料具有更快的降解速率;随着硫酸钙含量的增加,复合材料的失重率增加;在降解过程中降解液pH值维持在6.6～7.4之间。由于复合材料既具备有机组分良好的力学性能又具备硫酸钙良好的生物相容性和降解性能,所以该硫酸钙/聚酰胺复合材料可望在骨修复领域得到运用。     

羟基磷灰石/淀粉基复合生物材料

淀粉基(starch-based)材料是一类重要的生物降解聚合物,羟基磷灰石(HA)是人体骨骼的主要成分,以淀粉基材料为基体、以HA为增强材料的HA/淀粉基复合材料是一类新型的复合生物材料,其具有良好的生物相容性,在骨修复领域具有巨大的应用潜力.初步对该复合材料进行了归类,并介绍了其制备工艺、性能和应用等方面的研究近况,指出改进复合工艺、采用纳米级HA增强并进行表面改性是其发展趋势.     

牡蛎壳为原料制备医用CaCO3/HA复合生物材料

以牡蛎壳为原材料,通过水热法制备了碳酸钙(CaCO3)/羟基磷灰石(HA)复合材料,拟达到降低HA生产成本并改善其降解性能的目的。通过物相分析和SEM、TEM观察发现制得的CaCO3/HA复合材料呈现片层状,其微观形貌呈现纳米颗粒状。实验通过控制钙、磷元素的投料比例制备了HA含量为20%、40%、60%的三种CaCO3/HA复合材料(20%HA、40%HA、60%HA),通过ICP测试计算得出HA的实际含量为17.52%、34.30%、43.24%。随着HA含量的增加, CaCO3/HA复合材料的比表面积和热稳定性显著提升。体外降解实验结果表明,三种不同HA含量的复合材料在PBS模拟体液中14d的降解率分别为15.2%,12.0%和10.8%,降解率随HA比例的增高而降低。这些结果表明:水热法合成CaCO3/HA复合材料可通过钙、磷元素的投料比例来调控HA的转化率,进而调控CaCO3/HA复合材料的降解速率,实现其在骨科领域的潜在应用。     

纳米HA/PA6复合材料的体外生物活性

研究了PA6和纳米HA/PA6复合材料在模拟体液(SBF)中的行为变化,用IR,XRD,SEM和EDS等手段对材料的表面变化进行了分析,讨论了PA6和纳米HA/PA6复合材料的稳定性、亲水性和生物活性。结果表明:在SBF中PA6的吸水率大概在6%左右,纳米HA/PA6复合材料的吸水率有少量下降,PA6和纳米HA/PA6复合材料出现一定的溶解和降解。在SBF中,PA6表面形成Ca,P化合物中的Ca/P比例为1.12,与HA的理论值1.67有一定的差别;HA/PA6复合材料在其表面形成了HA沉积物和碳酸取代的磷灰石沉积物,Ca/P逐步变化为1.67,表现出较好的生物活性。复合材料表面沉积的HA和原来合成的HA具有相近的结晶形貌,该复合材料可作为优良的骨修复填充材料和组织工程支架材料。      

PLGA-HA-TiO2复合材料的制备和性能研究

通过冷压和固化技术成功的制备了PLGA-HA-TiO2复合材料,并考察了其机械性能和在模拟体液中的降解速率,采用扫描电子显微镜观察了其显微组织.结果表明,当复合材料中含25%(质量分数)的HA和2.5%(质量分数)的TiO2时,复合材料具有好的强度和塑性.HA含量少于50%(质量分数)时,对其在模拟体液中的降解速率基本没影响;反之,其降解速率会增加.在降解过程中,PLGA-HA-TiO2的表面形成磷灰石,表明该复合材料具有好的生物相容性.     

羟基磷灰石/聚己内酯-壳聚糖复合材料的制备与表征

为提高复合材料的力学性能和生物活性以聚己内酯(PCL) 、壳聚糖(CS) 、羟基磷灰石(HA)为原料,用Hakke流变仪挤出成型制备了不同 HA含量的HA/ PCL-CS复合材料,并对其进行了拉伸性能的测试,考察了复合材料浸渍于模拟体液(SBF)中的生物活性及其在生理盐水中的降解性能,用X射线衍射(XRD) 、傅里叶变换红外光谱(FTIR) 、扫描电镜(SEM) 、接触角测试仪对材料进行了表征。结果表明：复合材料的拉伸强度和断裂伸长率随 HA含量的增加而降低,而杨氏模量随 HA含量的增加而升高;亲水性能随着HA含量的增加而提高; HA/PCL-CS复合材料在模拟体液(SBF)中浸渍 14d后,在表面形成一层弱结晶的碳磷灰石(CHA)覆盖层 , 显示出良好的生物活性; PCL 的分子量随着降解时间的延长而降低,溶液pH值和质量损失率却增大,浸渍28d后,溶液pH值达到9. 54,失重率达到5.86%,显示出良好的生物可降解性。     

多孔ZnO/羟基磷灰石生物复合材料的制备与性能

利用放电等离子烧结技术制备多孔ZnO/羟基磷灰石（HA）生物复合材料,研究不同纳米ZnO含量对ZnO/HA复合材料微观结构、孔隙特征、力学性能、矿化和降解性能的影响。结果表明:烧结后ZnO/HA复合材料主要由HA相和ZnO相组成;随着ZnO含量提高,多孔ZnO/HA复合材料孔隙率缓慢增大,抗压强度略有减小,弹性模量变化不大;多孔ZnO/HA复合材料的孔隙率>40%,孔径在50～500 μm之间,抗压强度>148 MPa,弹性模量为6.5 GPa左右,能够满足骨修复材料的要求;模拟人工体液中矿化和降解实验表明,多孔ZnO/HA复合材料浸泡7天后表面开始形成大量类骨磷灰石层,且随着ZnO含量增加,磷灰石形成能力明显增强而降解速率加快。      

仿生矿化法制备可降解羟基磷灰石/氧化细菌纤维素复合材料

细菌纤维素是具有天然纳米网状结构的支架材料,对其进行氧化改性后可获得可调控的降解性能。通过仿生矿化氧化改性的细菌纤维素支架,制备了可降解羟基磷灰石/氧化细菌纤维素复合骨组织工程支架材料。观察并分析了仿生矿化过程氧化细菌纤维素的降解和羟基磷灰石的形成,并通过SEM、EDS、XRD对羟基磷灰石在可降解氧化细菌纤维素支架上沉积进行了表征,矿化7天的羟基磷灰石/氧化细菌纤维素复合材料表面和内部均有磷灰石形成,测得磷灰石的钙磷比为1.75,主要为羟基磷灰石,伴有少量碳羟磷灰石。结果表明,使用仿生矿化法成功获得了一种新型可降解羟基磷灰石/氧化纤维素复合材料支架。     

Recent advances in synthesis, characterization of hydroxyapatite/polyurethane composites and study of their biocompatible properties

The development of engineered biomaterials that mimic bone tissues is a promising research area that benefits from a growing interest. Polymers and polymer–ceramic composites are the principle materials investigated for the development of synthetic bone scaffolds thanks to their proven biocompatibility and biostability. Several polymers have been combined with calcium phosphates (mainly hydroxyapatite) to prepare nanocomposites with improved biocompatible and mechanical properties. Here, we report the hydrothermal synthesis in high pressure conditions of nanostructured composites based on hydroxyapatite and polyurethane functionalized with carboxyl and thiol groups. Cell-material interactions were investigated for potential applications of these new types of composites as coating for orthopedic implants. Physical–chemical and morphological characteristics of hydroxyapatite/polyurethane composites were evaluated for different compositions, showing their dependence on synthesis parameters (pressure, temperature). In vitro experiments, performed to verify if these composites are biocompatible cell culture substrates, showed that they are not toxic and do not affect cell viability.     

炭纤维增强羟基磷灰石/聚乳酸复合生物材料的力学性能和体外降解性能

采用溶液共混法制备了炭纤维(CF)增强羟基磷灰石(HA)/聚乳酸(PLA)三元复合生物材料。研究了该复合材料的力学性能和体外降解性能。CF/HA/PLA复合材料具有优异的力学性能, 弯曲强度和弯曲模量均随着HA含量的增加先升高后降低, 存在一个峰值, 可分别达到430MPa和26GPa。在PBS模拟体液中降解3个月, 弯曲强度和弯曲模量分别下降到初始值的30%和36%。SEM照片显示, 降解是从复合材料的界面开始的, 降解3个月后, 界面结合处出现缝隙, 吸水率增加到5%, 质量损失只有1.6%。PBS模拟体液的pH值下降在0.1之内, 有利于骨折部位的愈合。实验结果表明, 该复合材料的机械性能满足骨折内固定材料技术指标的要求。      

Fabrication and mechanical properties of PLA/HA composites: A study of in vitro degradation

The adverse effects of stress shielding from the use of high-modulus metallic alloy bio-implant materials has led to increased research into developing polymer–ceramic composite materials that match the elastic modulus of human bone. Of particular interest are poly-l-lactic acid–hydroxyapatite (PLA/HA)-based composites which are fully resorbable in vivo. However, their bioresorbability has a deleterious effect on the mechanical properties of the implant. The purpose of this study is to investigate, from a micromechanistic perspective, the in vitro degradation behavior of such composites manufactured using a simple hot-pressing route for two different hydroxyapatite particles: a fine-grained (average particle size ∼5 μm) commercial powder or coarser whiskers (∼ 25–30 μm long, ∼ 5 μm in diameter). We observed that composites with ceramic contents ranging between 70 and 85 wt.% have mechanical properties that match reasonably those of human cortical bone. However, the properties deteriorate with immersion in Hanks' Balanced Salt Solution due to the degradation of the polymer phase. The degradation is more pronounced in samples with larger ceramic content due to the dissolution of the smaller amount of polymer between the ceramic particles.     

纳米羟基磷灰石表面改性研究现状

纳米羟基磷灰石/聚合物复合材料在骨组织工程中得到广泛应用,但是纳米羟基磷灰石与聚合物的相容性非常差,在使用过程中易出现相分离现象,限制了其应用。通过在纳米羟基磷灰石表面接枝有机高分子,可以改变其表面性质、有效地改善HA与聚合物的相容性,从而提高复合材料的性能。文中综述了最近几年纳米羟基磷灰石表面改性的相关研究,着重对纳...     

Improved mechanical properties of HIPS/hydroxyapatite composites by surface modification of hydroxyapatite via in-situ polymerization of styrene

High impact polystyrene (HIPS)/hydroxyapatite (HA) composites are potential biomaterials for bone replacements due to their good biocompatibility and adequate mechanical properties. At the present work, the surface of the micron-sized hydroxyapatite (HA) particles was modified by in situ polymerization of styrene (St), then compounded with HIPS. The effect of the modification of HA surface on morphology and mechanical properties of HIPS/HA composites were investigated. The results showed that the HA particles does not inhibit the polymerization of St. The PS segments coated on the HA surface by in situ polymerization of St enhances the compatibility between HA and HIPS, improves the dispersion of HA particles in HIPS matrix, and enhances the interfacial adhesion between HA and matrix. Thereby, the stiffness, tensile strength and notch impact strength of HIPS/HA composites are improved at the same time. And there is a critical coating thickness of PS on the HA surface for the optimum mechanical properties of HIPS/HA composites.     

Three dimensional printed macroporous polylactic acid/hydroxyapatite composite scaffolds for promoting bone formation in a critical-size rat calvarial defect model

We have explored the applicability of printed scaffold by comparing osteogenic ability and biodegradation property of three resorbable biomaterials. A polylactic acid/hydroxyapatite (PLA/HA) composite with a pore size of 500 μm and 60% porosity was fabricated by three-dimensional printing. Three-dimensional printed PLA/HA, β-tricalcium phosphate (β-TCP) and partially demineralized bone matrix (DBM) seeded with bone marrow stromal cells (BMSCs) were evaluated by cell adhesion, proliferation, alkaline phosphatase activity and osteogenic gene expression of osteopontin (OPN) and collagen type I (COL-1). Moreover, the biocompatibility, bone repairing capacity and degradation in three different bone substitute materials were estimated using a critical-size rat calvarial defect model in vivo. The defects were evaluated by micro-computed tomography and histological analysis at four and eight weeks after surgery, respectively. The results showed that each of the studied scaffolds had its own specific merits and drawbacks. Three-dimensional printed PLA/HA scaffolds possessed good biocompatibility and stimulated BMSC cell proliferation and differentiation to osteogenic cells. The outcomes in vivo revealed that 3D printed PLA/HA scaffolds had good osteogenic capability and biodegradation activity with no difference in inflammation reaction. Therefore, 3D printed PLA/HA scaffolds have potential applications in bone tissue engineering and may be used as graft substitutes in reconstructive surgery.     

Fabrication and dissolution behavior of hollow hydroxyapatite microspheres intended for controlled drug release

Hollow hydroxyapatite (HA) microspheres were fabricated by a simple spray drying method in this study. Moreover, the dissolution behavior of these hollow HA microspheres after immersion in simulated body fluid (SBF) was also studied. The results indicated that the dissolution of the HA microspheres in SBF is not homogeneous in a layer-by-layer fashion but was preferential at different locations of the particle surface. Generically, dissolution preferentially occurs on the location with looser structure and high porosity of the microspheres. The degradable HA microspheres are expected to have potential applications in bone local drug delivery systems.     

Fixation of carbon fibre-reinforced carbon composite implanted into bone

The push-out test of three types of biomaterials: carbon fibre-reinforced carbon (CFRC), hydroxyapatite (HA), and surgical steel (SS) implanted into rabbits femurs was carried out. Hydroxyapatite was used as a positive control (good fixation expected in bone) and surgical steel was a negative one (potentially no fixation in bone). Regeneration of bone in contact with all implants was found three months after implantation. The shear strength between CFRC implants and bone was lower than with the HA implants and higher than the shear strength between the surgical steel and bone. Compressive strength of CFRC implants removed after the observation period was significantly lower than the compressive strength of non-implanted samples. It is concluded that the mechanical bonding between the CFRC implants and host tissues exists 3 months after intrabone implantation and is accompanied by a decrease of the strength of implants.