纳米羟基磷灰石/聚碳酸酯复合生物材料Ⅱ:体外生物活性

研究了纳米羟基磷灰石/聚碳酸酯(n-HA/ PC)生物复合材料在模拟体液(SBF)中的表面变化,并用傅里叶红外光谱(FTIR) 、X射线衍射仪(XRD)和扫描电子显微镜(SEM)对材料的表面变化进行了分析。结果表明,n-HA/PC生物复合材料在模拟体液(SBF)中浸泡后,表面会沉积碳酸化羟基磷灰石(CHA),随着浸泡时间的延长,沉积层变厚,CHA晶体形貌变得规整。对n-HA/PC复合材料进行了细胞实验,通过四唑盐(MTT)检测和扫描电镜观察,表明n-HA/PC复合材料无细胞毒性,细胞形态正常,是一种有应用前景的可承力骨修复替代材料。      

低温等离子体处理对纤维毡润湿性能的影响

通过低温等离子体技术对纤维毡进行表面改性,提高其表面润湿性。对未经过任何处理的熔喷聚乙烯纤维毡进行低温等离子体处理,通过接触角测量仪、红外光谱仪和扫描电镜对经过空气等离子体及丙烯酸气相等离子体处理的纤维毡进行表面接触角、官能团以及纤维表面形貌等特征进行表征。结果显示,随着放电时间和放电功率的增加,纤维毡表面亲水性得到了不断提升,改性后的纤维表面接枝了羟基(—OH)、醛基(—CHO)及羰基(C=O)等亲水性官能团,且表面形貌发生了一定的变化,表面微观粗糙度有所增大。这些一系列变化最终使纤维毡表面润湿性得到了有效改善。     

氧气等离子体处理对CFRP表面特性及胶接界面力学性能的影响EI北大核心CSCD

为改善碳纤维增强复合材料(CFRP)胶接界面力学性能,采用低温氧气等离子体处理设备对CFRP进行表面处理。利用接触角测量仪、扫描电子显微镜(SEM)、原子力显微镜(AFM)、X射线光电子能谱(XPS)对CFRP表面润湿性、表面能、表面形貌、表面化学组分等进行表征,通过双悬臂梁实验(DCB)对CFRP胶接界面力学性能进行研究。结果表明:随氧气等离子体处理时间从0 s增加至30 s,表面水接触角从97°降至29°,CFRP表面润湿性达到最佳,极性分量占比显著增多;随处理时间的增加,CFRP表面粗糙度和最大高低差降低,形成较多谷峰分布的纳米级沟壑,基体表面积增大;同时,表面C—O和C■O等含氧极性官能团含量明显增加,C—C/C—H和Si—C官能团含量减少,表面污染物得到有效清除和转化;与未处理相比,经氧气等离子体处理20 s后,CFRP胶接界面最大剥离载荷和Ⅰ型断裂韧度分别提高了1.01倍(62.73 N)和1.92倍(649.21 J/m 2)。研究发现,氧气等离子体处理可以显著改善CFRP表面物理化学特性,有利于CFRP与胶黏剂更好的黏结,提高胶接界面剥离强度与韧性。     

二水磷酸氢钙(DCPD)涂层对纯镁在模拟体液中腐蚀行为的影响

使用液相化学沉积技术在纯镁表面制备了二水磷酸氢钙(DCPD)涂层,并通过在SBF中的浸入腐蚀实验研究了涂层对镁耐蚀性的影响.结果表明,涂层提高了镁在仿生环境中的耐腐蚀能力,这种作用随时间的延长而增强;涂层抑制了Mg(OH)2腐蚀产物层的形成;DCPD在SBF中逐步溶解,但是在浸泡21d以后,试样表面仍然残留着DCPD颗粒.     

CaCO3晶须和PTFE对PEEK干摩擦性能的影响

用热压成型法制备CaCO3晶须和聚四氟乙烯(PTFE)填充的聚醚醚酮(PEEK)自润滑复合材料,研究了干摩擦条件下复合材料和45#钢环配副的摩擦磨损性能,并与纯PEEK进行了比较.结果表明:CaCO3晶须和PTFE明显改善了PEEK复合材料的减摩、耐磨和承载性能,其摩擦系数比纯PEEK降低约1/2,耐磨性提高27倍;摩擦稳定性显著提高,极限承载能力比纯PEEK提高1倍以上.CaCO3晶须降低了复合材料摩擦表面粘着、犁削和热变形,PTFE有助于复合材料在偶件表面形成连续、均匀的转移膜.PEEK自润滑复合材料的磨损机制主要是轻微的粘着和疲劳磨损.     

纯钛表面仿生矿化性能优化的研究

采用不同的碱液处理浓度和处理时间在80℃下处理纯钛的表面并在模拟体液(SBF)中进行仿生矿化.结果表明随着碱液处理浓度和处理时间的增加,纯钛表面在模拟体液中仿生矿化的能力增强.碱液处理的浓度是影响纯钛表面仿生矿化能力的主要因素.经10M/L的碱液处理48h后,纯钛表面生成的是具有(002)和(004)晶体取向的类骨磷灰石(HCA),HCA晶粒生长较大,相互连接形成空间紧凑的结构.     

TiZrCuPd金属玻璃表面沉积钙磷层的研究

采用电化学腐蚀的方法在Ti基金属玻璃表面构建多孔粗糙结构,改善其表面活性,并通过模拟人体溶液(SBF)中的仿生矿化生长的方法在此多孔粗糙表面上成功制备了类骨磷灰石层。利用扫描电子显微镜(SEM)、X射线衍射分析(XRD)、X射线光电子能谱(XPS)等分析手段对电化学腐蚀和仿生生长后的表面形貌、物相组成、成分价态等进行表征。结果表明,当HNO3浓度为10%,阳极电压为2V,处理温度60℃下可以在Ti40Zr10Cu36Pd14金属玻璃表面建立均匀表面多孔结构;具有这种多孔表面的金属玻璃经过热碱处理可以在模拟人体溶液(SBF)中快速沉积类骨磷灰石层;分析表明类骨磷灰石的主要组成是羟基磷灰石(HA)。     

碳纤维增强聚醚醚酮复合材料骨诱导修复植入体制备及微动摩擦学性能

引起植入体无菌松动的主要原因是植入体与骨组织之间的微动磨损。通过层叠法制备了碳纤维(CF)增强聚醚醚酮(PEEK)复合材料,在模拟体温37℃、模拟体液(SBF)润滑条件下,探究CF/PEEK复合材料的基本力学性能和截面微动摩擦学性能。通过改变法向载荷和位移幅值,建立了摩擦力(Ft)-位移幅值(D)曲线、微动运行工况图和摩擦系数曲线,通过三维白光干涉仪、扫描电子显微镜(SEM)对CF/PEEK复合材料进行磨损机制探究。结果表明：随着法向载荷的减少和位移幅值的增加,微动由部分滑移区、混合区向滑移区转变。摩擦系数曲线整体较为平稳,摩擦系数随着法向载荷的增加而降低,随着位移幅值的增加而增加,磨损体积随着载荷和位移幅值的增加而增加。且CF/PEEK复合材料截面也有较好的微动性能,磨损机制主要为磨粒磨损和疲劳磨损。通过对复合材料截面摩擦学特性分析,为CF/PEEK复合材料替代金属植入体提供一定的理论基础。     

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。      

钛涂覆多孔羟基磷灰石涂层的制备及其生物活性

在纯钛基体表面通过电泳沉积的方法制得壳聚糖/羟基磷灰石(CS/HA)复合涂层, 然后将复合涂层烧结形成多孔HA涂层。采用SEM对多孔HA涂层的形貌进行观察, XRD分析涂层的物相组成, 粘结拉伸实验测定涂层与基体的结合强度, 1.5倍人体模拟体液(1.5SBF)浸泡测定涂层的生物活性。结果表明: 当悬浮液中CS与HA质量比为1∶1时, 制得的CS/HA复合涂层经过700℃烧结处理, 涂层中CS热分解致孔形成多孔HA涂层, 孔径在10~25 μm, 涂层与基体的结合强度可达19.5 MPa; 在1.5SBF中浸泡5天后, 多孔HA涂层表面完全碳磷灰石化, 呈现较好的生物活性。      

Surface activation of polyetheretherketone (PEEK) and formation of calcium phosphate coatings by precipitation

Plasma activation of polyetheretherketone (PEEK) surfaces and the influence on coating formation in a supersaturated calcium phosphate solution was investigated in this study. It was observed that plasma treatment in a N2/O2 plasma had a significant effect on the wettability of the PEEK surface. The contact angle decreased from 85° to 25° after plasma treatment. Cell culture testing with osteoblastic cell lines showed plasma activation not to be disadvantageous to cell viability. X-ray photoelectron spectroscopy (XPS) analysis was performed to characterize the chemical composition of the PEEK surfaces. It was observed that the O1s intensity increased with plasma activation time. At the C1s peak the appearance of a shoulder at higher binding energies was observed. Coating of PEEK was performed in a supersaturated calcium phosphate solution. Coating thicknesses of up to 50 m were achieved after 24 days of immersion. Plasma activation followed by nucleation in a highly saturated hydroxyapatite solution had a positive effect on the growth rate of the layer on PEEK. Chemical analysis revealed that the coating consists of a carbonate-containing calcium phosphate.     

Differentiation of human mesenchymal stem cells on plasma-treated polyetheretherketone

Polyetheretherketone (PEEK) generally exhibits physical and chemical characteristics that prevent osseointegration. To activate the PEEK surface, we applied oxygen and ammonia plasma treatments. These treatments resulted in surface modifications, leading to changes in nanostructure, contact angle, electrochemical properties and protein adhesion in a plasma power and process gas dependent way. To evaluate the effect of the plasma-induced PEEK modifications on stem cell adhesion and differentiation, adipose tissue-derived mesenchymal stem cells (adMSC) were seeded on PEEK specimens. We demonstrated an increased adhesion, proliferation, and osteogenic differentiation of adMSC in contact to plasma-treated PEEK. In dependency on the process gas (oxygen or ammonia) and plasma power (between 10 and 200 W for 5 min), varying degrees of osteogenic differentiation were induced. When adMSC were grown on 10 and 50 W oxygen and ammonia plasma-treated PEEK substrates they exhibited a doubled mineralization degree relative to the original PEEK. Thus plasma treatment of PEEK specimens induced changes in surface chemistry and topography and supported osteogenic differentiation of adMSC in vitro. Therefore plasma treated PEEK holds perspective for contributing to osseointegration of dental and orthopedic load-bearing PEEK implants in vivo.     

A comparative study on mechanical properties of carbon fiber/PEEK composites

The aim of this work was to improve mechanical properties such as flexural strength and interlaminar shear strength (ILSS) of polyetheretherketone (PEEK) thermoplastic polymer which has very high processing temperature due to its high melting temperature. Carbon fiber (CF) surface was modified by two different methods: oxidative and non-oxidative. Piranha solution and chromate solution were used for chemical treatment (oxidative treatment), and silicone based polymers were used for polymer coating (non-oxidative). The changes on the surface structure and surface chemistry were characterized by scanning electron microscopy and Fourier transform infrared spectroscopy (FTIR), respectively. FTIR results indicate that coating fibers decreases carbon element content, whereas increases the oxygen and silicone content as well as their functional groups on the surface. Flexural strength and ILSS properties of CF/PEEK composites were measured according to ASTM D-790 and ASTM D2344, respectively.     

Electrophoretic deposition of polyetheretherketone (PEEK) and PEEK/Bioglass® coatings on NiTi shape memory alloy wires

Polyetheretherketone (PEEK) and PEEK/Bioglass® coatings were produced on shape memory alloy (NiTi, Nitinol®) wires using electrophoretic deposition (EPD). Best results were achieved with suspensions of PEEK powders in ethanol in the range (1–6 wt%), using a deposition time of 5 minutes and applied voltage of 20 Volts. EPD using these parameters led to high quality PEEK coatings with a homogeneous microstructure along the wire length and a uniform thickness of up to 15 μm without development of cracks or the presence of large voids. Suspensions of PEEK powders in ethanol with addition of Bioglass® particles (0.5–2 wt%) (size < 5 μm) were used to produce PEEK/Bioglass® coatings. Sintering was carried out as a post EPD process in order to densify the coatings and to improve the adhesion of the coatings to the substrate. The sintering temperature was 340 °C, sintering time 20 min and heating rate 300 °C/h. Sintering led to uniform and dense PEEK and PEEK/Bioglass® coatings without any cracks. The bioactive behaviour of PEEK/Bioglass® composite coatings was investigated by immersion in acellular simulated body fluid (SBF) for up to two weeks. As expected, hydroxyapatite crystals formed on the surface of the coated wires after 1 week in SBF, confirming the bioactive character of the coatings. The results have demonstrated for the first time that EPD is a very convenient method to obtain homogeneous and uniform bioactive PEEK and PEEK/Bioglass® coatings on Nitinol® wires for biomedical applications.     

Polyetheretherketone and titanium surface treatments to modify roughness and wettability-Improvement of bioactivity and antibacterial properties

Among the materials available for implant production,titanium is the most used while polyetherether-ketone (PEEK) is emerging thanks to its stability and to the mechanical properties similar to the ones of the bone tissue.Material surface properties like roughness and wettability play a paramount role in cell adhesion,cell proliferation,osteointegration and implant stability.Moreover,the bacterial adhesion to the biomaterial and the biofilm formation depend on surface smoothness and hydrophobicity.In this work,two different treatments,sandblasting and air plasma,were used to increase respectively roughness and wettability of two materials:titanium and PEEK.Their effects were analyzed with profilometry and contact angle measurements.The biological properties of the material surfaces were also investigated in terms of cell adhesion and proliferation of NIH-3T3 cells,MG63 cells and human Dental Pulp Stem Cells.Moreover,the ability of Staphylococcus aureus to adhere and form a viable biofilm on the samples was evaluated.The biological properties of both treatments and both materials were compared with samples of Synthegra(R) titanium,which underwent laser ablation to obtain a porous micropatterning,character-ized by a smooth surface to discourage bacterial adhesion.All cell types used were able to adhere and proliferate on samples of the tested materials.Cell adhesion was higher on sandblasted PEEK samples for both MG63 and NIH-3T3 cell lines,on the contrary,the highest proliferation rate was observed on sandblasted titanium and was only slightly dependent on wettability;hDPSCs were able to proliferate similarly on sandblasted samples of both tested materials.The highest osteoblast differentiation was ob-served on laser micropatterned titanium samples,but similar effects,even if limited,were also observed on both sandblasted materials and air plasma treated titanium.The lowest bacterial adhesion and biofilm formation was observed on micropatterned titanium samples whereas,the highest biofilm formation was detected on sandblasted PEEK samples,and in particular on samples not treated with air-plasma,which displayed the highest hydrophobicity.The results of this work showed that all the tested materials were able to sustain osteoblast adhesion and promote cell proliferation;moreover,this work highlights the fea-sible PEEK treatments which allow to obtain surface properties similar to those of titanium.The results here reported,clearly show that cell behavior depends on a complex combination of surface properties like wettability and roughness and material nature,and while a rough surface is optimal for cell adhesion,a smooth and less hydrophilic surface is the best choice to limit bacterial adhesion and biofilm formation.     

Micro-CT Analysis of Implanted Poly-Ether-Ether-Ketone Scaffolds: Plasma Immersion Ion Implantation Increases Osteoconduction

Poly-ether-ether-ketone (PEEK) is a biocompatible, high-strength polymer with biomechanical properties similar to soft bone that has been proposed as an alternative to titanium for orthopedic implants. Herein, micro-CT imaging of a 3D printed PEEK scaffold treated with plasma immersion ion implantation (PIII) to assess the degree of osteoconduction relative to an identical untreated structure, by implantation in the scapula of sheep, is performed. To overcome the lack of contrast between soft tissue and PEEK, a customized apparatus and alignment technique is designed and constructed. Principal component analysis is used to accurately locate the boundaries of the implant in the 3D dataset, with respect to reference coordinates. It is found that, within the interior volume of the scaffold, the PIII treated PEEK contains bone that is both more dense and in higher amounts than for untreated PEEK. The untreated PEEK shows more bone immediately outside the boundaries of the scaffold, indicating a lower affinity of the untreated scaffold for in-diffusion of osteocytes and associated mineralization. The greater osteoconduction of the PIII treated scaffold is attributed to the improvement in hydrophilicity and the provision of protein covalent binding.     

Polyetheretherketone (PEEK) for medical applications

Polyetheretherketone (PEEK) is a polyaromatic semi-crystalline thermoplastic polymer with mechanical properties favorable for bio-medical applications. Polyetheretherketone forms: PEEK-LT1, PEEK-LT2, and PEEK-LT3 have already been applied in different surgical fields: spine surgery, orthopedic surgery, maxillo-facial surgery etc. Synthesis of PEEK composites broadens the physicochemical and mechanical properties of PEEK materials. To improve their osteoinductive and antimicrobial capabilities, different types of functionalization of PEEK surfaces and changes in PEEK structure were proposed. PEEK based materials are becoming an important group of biomaterials used for bone and cartilage replacement as well as in a large number of diverse medical fields. The current paper describes the structural changes and the surface functionalization of PEEK materials and their most common biomedical applications. The possibility to use these materials in 3D printing process could increase the scientific interest and their future development as well.     

Response of primary fibroblasts and osteoblasts to plasma treated polyetheretherketone (PEEK) surfaces

Polyetheretherketone (PEEK) is a synthetic polymer with suitable biomechanical and stable chemical properties, which make it attractive for use as an endoprothetic material and for ligamentous replacement. However, chemical surface inertness does not account for a good interfacial biocompatibility, and PEEK requires a surface modification prior to its application in vivo.In the course of this experimental study we analyzed the influence of plasma treatment of PEEK surfaces on the cell proliferation and differentiation of primary fibroblasts and osteoblasts. Further we examined the possibility of inducing microstructured cell growth on a surface with plasma-induced chemical micropatterning.We were able to demonstrate that the surface treatment of PEEK with a low-temperature plasma has significant effects on the proliferation of fibroblasts. Depending on the surface treatment, the proliferation rate can either be stimulated or suppressed. The behavior of the osteoblasts was examined by evaluating differentiation parameters.By detection of alkaline phosphatase, collagen I, and mineralized extracellular matrix as parameters for osteoblastic differentiation, the examined materials showed results comparable to commercially available polymer cell culture materials such as tissue culture polystyrene (TCPS). Further microstructured cell growth was produced successfully on micropatterned PEEK foils, which could be a future tool for bioartificial systems applying the methods of tissue engineering.These results show that chemically inert materials such as PEEK may be modified specifically through the methods of plasma technology in order to improve biocompatibility.The first two authors share first authorship.     

In vitro and in vivo evaluation of bone morphogenetic protein-2 (BMP-2) immobilized collagen-coated polyetheretherketone (PEEK)

Polyetheretherketone (PEEK) is regarded as one of the most potential candidates of biomaterials in spinal implant applications. However, as a bioinert material, PEEK plays a limited role in osteoconduction and osseointegration. In this study, recombinant human bone morphogenetic protein-2 (rhBMP-2) was immobilized onto the surface of collagen-coated PEEK in order to prepare a multi-functional material. After adsorbed onto the PEEK surface by hydrophobic interaction, collagen was cross-linked with N-(3-dimethylaminopropyl)-N'-ethyl carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS). EDC/NHS system also contributed to the immobilization of rhBMP-2. Water contact angle tests, XPS and SEM clearly demonstrated the surface changes. ELISA tests quantified the amount of rhBMP-2 immobilized and the release over a period of 30 d. In vitro evaluation proved that the osteogenesis differentiation rate was higher when cells were cultured on modified PEEK discs than on regular ones. In vivo tests were conducted and positive changes of major parameters were presented. This report demonstrates that the rhBMP-2 immobilized method for PEEK modification increase bioactivity in vitro and in vivo, suggesting its practicability in orthopedic and spinal clinical applications.     

聚醚醚酮与髌骨软骨间的生物摩擦学特性

以聚醚醚酮(polyetheretherketone,PEEK)与天然软骨为研究对象,医用CoCrMo和天然软骨作为PEEK的对比材料,开展往复滑动摩擦磨损实验,研究法向载荷、滑移速率、摩擦配副对其摩擦磨损行为的影响。结果表明:在小牛血清润滑的条件下,天然股骨软骨/髌骨软骨的摩擦因数最小,PEEK/髌骨软骨摩擦因数明显低于CoCrMo/髌骨软骨,PEEK/髌骨软骨配副的软骨表面磨损轻微,CoCrMo/髌骨软骨配副的软骨表面损伤严重;PEEK/髌骨软骨配副间的摩擦因数随法向载荷的增大而减小,在低载荷条件下(10～20N)表现明显,且法向载荷越大,PEEK表面磨痕越深,摩擦副磨损越严重;PEEK/髌骨软骨配副间的摩擦因数随滑移速率的增大而增大,在高滑移动速率条件下(10～20mm/s)明显,且滑移速率越大,PEEK表面磨痕越深,摩擦副磨损越严重;相对于滑移速率,载荷对摩擦因数的影响更大。