镍钛形状记忆合金的表面改性对其生物相容性的影响

镍钛形状记忆合金(nickeltitaniumshapememoryalloys,NiTi-SMA)的发展符合生物学固定(biologicalosteosynthesis,BO)的思想,是一种理想的骨科内固定材料。NiTi-SMA中含有50%左右的镍。针对释出的镍元素是否会产生细胞毒性、表面改性的NiTi-SMA生物相容性究竟如何等问题,综述了NiTi-SMA生物相容性方面的最新进展、存在问题和发展方向。     

镍钛形状记忆合金的生物相容性研究进展

镍钛形状记忆合金(Nickel titanium shape memory alloys,Ni Ti-SMA)因具有良好的生物相容性、形状记忆效应以及超弹性等优异性能成为理想的体内固定材料,目前已广泛的应用于临床治疗。由于镍钛形状记忆合金的形状记忆效应和超弹性可以有效避免应力遮蔽引起的材料断裂,因而有望长期存于人体内,但是合金在人体内受腐蚀释放的镍离子存在生物毒性,对局部组织有致敏甚至是致癌作用,所以又限制了其在临床上的广泛应用。本文综述了镍钛形状记忆合金生物相容性相关的文献,总结镍钛形状记忆合金在体外、动物体内生物相容性以及临床应用的生物相容性方面的研究进展,并指出镍钛形状记忆合金的表面处理在提高其生物相容性方面的重要性。     

生物医用金属材料表面改性研究

本文主要对生物医用金属材料表面改性的几种方法进行了综述,并对表面改性在生物金属材料方面的应用作出了展望.     

镍钛形状记忆合金性能及生物相容性研究进展

1963年美国海军军械研究室Buehler等偶然间发现了等原子NiTi合金(当时作为阻尼材料开发研究)在室温(马氏体态)经形变(弯曲)、再经加热(与点燃的香烟火苗接触，发生逆相变：马氏体→母相)后，自动回复母相态形状(自动弹直)；由于累积了马氏体相变的知识，这类合金(具有热弹性马氏体相变的合金)在马氏体态变形，经逆相变，能自动回复到母相形状，于是命名为形状记忆。自此，形状记忆合金及“NiTinol”(指Ni-Ti-navy-ordnance-laboratory)开始进入实用阶段。     

镍钛形状记忆合金表面改性后的血液相容性

背景：镍钛形状记忆合金植入人体内必需要有很好的生物相容性和生物安全性。 目的：观察分析镍钛形状记忆合金表面改性后对其生物相容性的影响。 方法：将镍钛形状记忆合金随机分为两组,经阴极电沉积法处理的材料为实验组,未经处理的为空白组,通过扫描电镜观察实验组材料表面的变化,并测定材料的溶血率和动态凝血时间。体外培养骨髓基质干细胞,与两组材料复合培养,通过MTT法检测两组材料中细胞存活数量。 结果与结论：镍钛形状记忆合金表面改性后,表面出现由很多的纳米级颗粒紧密聚集形成的Ti-O膜,实验组材料的溶血率下降,凝血时间延长,两组材料与骨髓基质干细胞复合培养第2,4,6天,实验组吸光度比空白组明显增高(P < 0.05)。说明镍钛形状记忆合金经阴极电沉积法表面改性后具有较好的生物相容性和生物安全性。     

生物学内固定材料——β钛合金与镍钛形状记忆合金

生物学内固定(biological osteosynthesis，BO)是骨折治疗观念的发展方向，β钛合金与镍钛形状记忆合金的发展与BO的思想吻合，因此具有广阔的发展前景。本综述了上述材料的多项优良性能，着重介绍了基础研究和临床应用的最新进展。     

生物学内固定材料--β钛合金与镍钛形状记忆合金

生物学内固定(biological osteosynthesis,BO)是骨折治疗观念的发展方向,β钛合金与镍钛形状记忆合金的发展与BO的思想吻合,因此具有广阔的发展前景.本文综述了上述材料的多项优良性能,着重介绍了基础研究和临床应用的最新进展.     

医用钛合金的表面改性

金属材料是目前临床骨科中应用最广泛的生物材料之一。临床应用的金属材料主要包括：不锈钢、钴基合金、钛合金及记忆合金等。传统的不锈钢、钴基合金，由于其自身的缺陷，在临床应用中发现存在不少问题，如生物相容性差，组织反应严重：耐磨性差，金属离子溶出，导致金属离子的致敏、致癌反应：弹性模量高，易产生应力遮挡等。近几年来，钛合金以其良好的生物相容性、与骨组织相近的弹性模量及在生物环境下优良的抗腐蚀性，在临床得到了广泛的应用。对Co-Cr合金、不锈钢在临床应用中的主导地位，提出了严重的挑战，并有逐步取代Co-Cr合金、不锈钢内植入物的趋势。     

镍钛形状记忆合金血管内支架组织相容性实验研究

将锥形记忆合金支架分别植入６只猪右侧髂动脉。用以研究镍钛形状记忆合金血管内支架生物相容性，支架植入前入植入后８个月，观测动物血常规，肝肾功能以及毛发中镍钛元素含量，均无明显变化（Ｐ〉０．０５），支架植入后８个月处死动物，全身重要脏器（肝、脾、肾、肺、心、脑等）病理学检查结构正常，无淋巴细胞和单核细胞浸润，支架植入部位上游血管壁内膜光滑，内皮细胞结构正常，内弹力板完整，支架植入段为完整肉芽组织阻塞，     

生物医用钛合金材料的生物及力学相容性

背景：保证生物材料优良的生物及力学相容性是研制开发外科植入物及矫形器械产品的关键,但目前对其研究缺乏系统性和统一性认识。 目的：初步分析生物医用钛合金材料生物及力学相容性的概念、内涵,指导医疗器械产品的选型设计与应用。 方法：应用计算机检索PubMed、Elsiver、Springerlink、CNKI及维普等数据库1995至2012年相关文献,围绕“生物及力学相容性”主题词,探讨合金成分、显微组织及相变控制和材料表面状态优化等因素对钛合金材料生物及力学相容性的影响规律。 结果与结论：生物及力学相容性是一个综合评价概念。进行医用钛合金材料选型设计时,首先要求合金中的组成元素无不良反应,并保证其与组织、血液及免疫和全身反应的安全性,同时要求所添加元素对钛合金的机械性能等其他性能不良影响最小。钛合金中常见的合金化元素主要包括α相稳定元素、β相稳定元素和中性元素3类。要使生物医用钛合金植入材料获得优良的生物及力学相容性,对材料内部显微组织和相变进行控制,以及开展材料表面状态改性优化也至关重要。但不能单纯追求一种钛合金的低模量或高强度等某一单项力学指标与人体骨组织接近或匹配而简单判定其生物力学相容性的优劣。     

Carbon plasma immersion ion implantation of nickel-titanium shape memory alloys

Nickel-titanium (NiTi) shape memory alloys possess super-elasticity in addition to the well-known shape memory effect and are potentially suitable for orthopedic implants. However, a critical concern is the release of harmful Ni ions from the implants into the living tissues. We propose to enhance the corrosion resistance and other surface and biological properties of NiTi using carbon plasma immersion ion implantation and deposition (PIII&D). Our corrosion and simulated body fluid tests indicate that either an ion-mixed amorphous carbon coating fabricated by PIII&D or direct carbon PIII can drastically improve the corrosion resistance and block the out-diffusion of Ni from the materials. Our tribological tests show that the treated surfaces are mechanically more superior and cytotoxicity tests reveal that both sets of plasma-treated samples favor adhesion and proliferation of osteoblasts.     

A comparative study of the cytotoxicity and corrosion resistance of nickel-titanium and titanium-niobium shape memory alloys

Nickel-titanium (NiTi) shape memory alloys (SMAs) are commonly used in a range of biomedical applications. However, concerns exist regarding their use in certain biomedical scenarios due to the known toxicity of Ni and conflicting reports of NiTi corrosion resistance, particularly under dynamic loading. Titanium-niobium (TiNb) SMAs have recently been proposed as an alternative to NiTi SMAs due to the biocompatibility of both constituents, the ability of both Ti and Nb to form protective surface oxides, and their superior workability. However, several properties critical to the use of TiNb SMAs in biomedical applications have not been systematically explored in comparison with NiTi SMAs. These properties include cytocompatibility, corrosion resistance, and alterations in alloy surface composition in response to prolonged exposure to physiological solutions. Therefore, the goal of the present work was to comparatively investigate these aspects of NiTi (49.2 at.% Ti) and TiNb (26 at.% Nb) SMAs. The results from the current studies indicate that TiNb SMAs are less cytotoxic than NiTi SMAs, at least under static culture conditions. This increased TiNb cytocompatibility was correlated with reduced ion release as well as with increased corrosion resistance according to potentio-dynamic tests. Measurements of the surface composition of samples exposed to cell culture medium further supported the reduced ion release observed from TiNb relative to NiTi SMAs. Alloy composition depth profiles also suggested the formation of calcium phosphate deposits within the surface oxide layers of medium-exposed NiTi but not of TiNb. Collectively, the present results indicate that TiNb SMAs may be promising alternatives to NiTi for certain biomedical applications.     

金纳米棒的表面改性及生物相容性

背景：金纳米棒制备过程中加入的十六烷基三甲基溴化铵可促进棒状金纳米颗粒的形成,保证金纳米棒良好的分散性,但也会产生一定毒性。 目的：评价表面修饰后金纳米棒的生物相容性。 方法：运用种子介导生长法制备金纳米棒,以改良后的奥伯法对其表面进行二氧化硅修饰,采用紫外分光光度计和透射电子显微镜对其进行表征,将修饰后的金纳米棒配制成不同浓度(60,45,30,15 μmol/L),分别与肝癌bel-7402细胞及胃癌MGC-803细胞孵育,采用CCK-8法检测细胞相对增殖率,细胞毒性级别。 结果与结论：表面修饰后的金纳米棒分散性好,其特殊的光学性质未有改变,分别在500,825 nm处有强吸收峰。不同浓度金纳米棒处理后,肝癌bel-7402细胞的相对增殖率在95%-100%之间,胃癌MGC-803细胞的相对增殖率在99%-103%之间,两组细胞的毒性评级均为0级或1级,无细胞毒性。表明经二氧化硅表面修饰后的金纳米棒具有良好的生物相容性。     

New oxidation treatment of NiTi shape memory alloys to obtain Ni-free surfaces and to improve biocompatibility

Various oxidation treatments were applied to nearly equiatomic NiTi alloys so as to form a Ni-free protective oxide on the surface. Sample surfaces were analyzed by X-ray Photoelectron Spectroscopy, and NiTi transformation temperatures were determined by differential scanning calorimetry (DSC) before and after the surface treatment. An ion release experiment was carried out up to one month of immersion in SBF for both oxidized and untreated surfaces. The results show that oxidation treatment in a low-oxygen pressure atmosphere leads to a high surface Ti/Ni ratio, a very low Ni surface concentration and a thick oxide layer. This oxidation treatment does not significantly affect the shape memory properties of the alloy. Moreover, the oxide formed significantly decreases Ni release into exterior medium comparing with untreated surfaces. As a consequence, this new oxidation treatment could be of great interest for biomedical applications, as it could minimize sensitization and allergies and improve biocompatibility and corrosion resistance of NiTi shape memory alloys.     

Characteristics of porous nickel-titanium alloys for medical applications

We investigate the behavior of NiTi porous alloys, possessing the property of shape memory, by using different characterization methods XPS, Auger, DSC and SEM. The study mainly focuses on the determination of porosity, surface characteristics and the phase transformation. In the case of porous material the biomechanical compatibility is closely related to the internal structure and porosity distribution. To describe appropriately the influence of the properties of NiTi on the memory shape, two types of materials provided by different sources has been analyzed. Despite the fact that both materials present different pores size, they exhibit an open and interconnected porosity. Our measurements show that the temperature of the inception of the martensite-austenite phase transition occurs at 60 degrees C, which is by 20 degrees C greater than the body temperature. Moreover, we show that the surface characteristics can be greatly influenced by heat treatment. Furthermore, we observe that the R-phase occurs only for one of the used materials after its heat treatment. The correlation between the composition and the other characteristics measured has been found.     

Investigation of nickel suppression and cytocompatibility of surface-treated nickel-titanium shape memory alloys by using plasma immersion ion implantation

Nickel-titanium (NiTi) shape memory alloys are increasingly being used in orthopedic applications. However, there is a concern that Ni is harmful to the human body. We have recently investigated the use of nitrogen, or oxygen plasma immersion ion implantation to mitigate this deleterious effect. Our results reveal that the near-surface Ni concentration in all the treated samples is significantly suppressed. In addition, our in vitro tests show that the plasma-treated surfaces are cytologically compatible allowing the attachment and proliferation of osteoblasts. Among the two types of samples, the best biological effects are found on the samples with nitrogen implantation.     

Corrosion resistance, surface mechanical properties, and cytocompatibility of plasma immersion ion implantation-treated nickel-titanium shape memory alloys

Nickel-titanium shape memory alloys are promising materials in orthopedic applications because of their unique properties. However, for prolonged use in a human body, deterioration of the corrosion resistance of the materials becomes a critical issue because of the increasing possibility of deleterious ions released from the substrate to living tissues. We have investigated the use of nitrogen, acetylene, and oxygen plasma immersion ion implantation (PIII) to improve the corrosion resistance and mechanical properties of the materials. Our results reveal that the corrosion resistance and mechanical properties such as hardness and elastic modulus are significantly enhanced after surface treatment. The release of nickel is drastically reduced as compared with the untreated control. In addition, our in vitro tests show that the plasma-treated surfaces are well tolerated by osteoblasts. Among the three types of samples, the best biological effects are observed on the nitrogen PIII samples.     

Effect of nickel-titanium shape memory metal alloy on bone formation

The aim of this study was to determine the biocompatibility of NiTi alloy on bone formation in vivo. For this purpose we used ectopic bone formation assay which goes through all the events of bone formation and calcification. Comparisons were made between Nitinol (NiTi), stainless steel (Stst) and titanium-aluminium (6%)-vanadium (4%) alloy (Ti-6Al-4V), which were implanted for 8 weeks under the fascia of the latissimus dorsi muscle in 3-month-old rats. A light-microscopic examination showed no chronic inflammatory or other pathological findings in the induced ossicle or its capsule. New bone replaced part of the decalcified matrix with mineralized new cartilage and bone. The mineral density was measured with peripheral quantitative computed tomography (pQCT). The total bone mineral density (BMD) values were nearly equal between the control and the NiTi samples, the Stst samples and the Ti-6Al-4V samples had lower BMDs. Digital image analysis was used to measure the combined area of new fibrotic tissue and original implanted bone matrix powder around the implants. There were no significant differences between the implanted materials, although Ti-6Al-4V showed the largest matrix powder areas. The same method was used for measurements of proportional cartilage and new bone areas in the ossicles. NiTi showed the largest cartilage area (p < or = 0.05). Between implant groups the new bone area was largest in NiTi. We conclude that NiTi has good biocompatibility, as its effects on ectopic bone formation are similar to those of Stst, and that the ectopic bone formation assay developed here can be used for biocompatibility studies.     

医用聚碳酸酯的涂层修饰及生物相容性研究

目的 研制低分子肝素钠(LMWH)涂层和多醛基氧化海藻酸钠(OSA)涂层的聚碳酸酯,并对其生物相容性进行评价.方法 利用化学接枝改性方法制备涂层材料,进行表征并验证涂层稳定性;通过接触角测定、体外血清蛋白、血小板黏附试验、体外凝血试验等进行生物相容性评价.结果 分析红外光谱,发现涂层后材料出现与涂层物相关的吸收峰变化,定量结果显示材料表面涂层量稳定.与未涂层材料相比,涂层材料表面与水的接触角减小,血清蛋白、血小板黏附量显著减少,凝血酶原时间(PT)和活化部分凝血活酶时间(APTT)显著延长,其差异有统计学意义(P＜0.05).与LMWH涂层材料相比,OSA涂层材料抗凝效果略差,但其蛋白黏附量、表面接触角小于LMWH涂层,差异具有统计学意义(P＜0.05).结论 应用化学接枝改性方法制备LMWH、OSA涂层的聚碳酸酯,其涂层稳定,生物相容性显著改善.     

钛铌涂层镍钛记忆合金的生物安全性及生物相容性

目的NiTi记忆合金表面分别进行不涂层、Ti涂层和TiNb涂层表面修饰后,对Ni2+的释放安全性及生物相容性进行分析。方法将NiTi记忆合金制备成10mm×10mm×10mm立方体,一组采用等离子喷涂技术分别进行Ti涂层和TiNb涂层,另一组仅表面抛光清洗,不进行涂层。经X射线光电子能谱(XPS)测定植入体的表面成分,扫描电镜(SEM)和X射线荧光分析显微镜(XFAM)测定涂层厚度和形态。成年杂种犬18只,随机分为4组,NiTi合金组(无表面喷涂)、Ti涂层组、TiNb涂层组各5只,空白对照组3只。实验组分别于骶棘肌内埋入合金,每只犬每侧植入5枚,共10枚。空白对照组术式相同,只是不植入任何物体即缝合。12个月后处死取材,采用石墨炉原子吸收仪(GFAAS)分别检测心、肝、脾、肺、肾、脑、骨、鼻咽黏膜、血液、肌肉组织中Ni2+含量。对植入体周围纤维囊厚度进行显微镜下测量和结构分析,并进行统计学分析。结果①涂层表面光滑、平整、均匀,厚度约3.25μm;②Ti和TiNb涂层可成功屏蔽合金表面Ni元素。NiTi合金组肝、肾组织中Ni2+含量分别是空白组的1.6和2.4倍;Ti涂层组、TiNb涂层组、空白组之间Ni2+含量无显著差异;③组织学观察三组植入体周围肌肉组织发现无明显巨噬细胞和炎性细胞浸润,具有良好的肌肉组织生物相容性;④植入体周围纤维囊厚度定量分析NiTi合金组、Ti涂层组和TiNb涂层组厚度分别为38.8、25.8和26.1μm,NiTi组对Ti组和TiNb组差异极显著(P0.01),而Ti组和TiNb组间无显著差异。结论经Ti或TiNb涂层后的NiTi记忆合金可有效防止金属表面Ni2+释放,提高NiTi合金的生物相容性和安全性。