冠状动脉支架材料的研究进展

冠状动脉支架置入术作为治疗心血管狭窄引起的冠心病的主要方法之一,得到了较为广泛、深入的研究.从材料的角度系统介绍了冠状动脉支架,包括支架基体材料、支架表面涂层材料和所载药物,并简要说明了药物涂层的组装工艺和冠状动脉支架的发展趋势.     

碳纳米管聚合物复合材料在生物医药领域应用的研究进展

碳纳米管因其可以穿透细胞膜和生物体的多重屏障进入细胞和生物体内而在生物医药领域具有广泛应用前景。介绍了碳纳米管的基本性质,概述了碳纳米管聚合物复合材料的生物相容性,并在此基础上综述了其在生物电驱动材料、支架材料以及药物载体等方面应用的最新成果,展望了未来碳纳米管聚合物复合材料在生物医药领域的发展方向。     

屏蔽层对支架涂层药物缓释影响的体外研究

载药涂层的药物释放行为对于药物洗脱支架的临床治疗效果具有非常重要的意义。讨论了在聚碳酸酯载药涂层外面再加一层空白聚合物层(即屏蔽层)对药物释放的影响。从4方面的体外实验证明屏蔽层(drug free polymer layer,DFPL)可以防止聚碳酸酯载药涂层药物"暴释"的现象,并且屏蔽层厚度和释放速率不是简单的比例关系,以及不同的药物梯度和不同的屏蔽层材料对药物释放有不同的影响效果。     

聚乳酸类可生物降解材料在缓控释药物制剂中的应用

综述了用聚乳酸类可生物降解型高分子材料制备缓控释药物载体的研究现状.分别介绍了该类材料在微粒给药载体、凝胶制剂、缓释支架和埋植制剂的应用及其制备方法.阐述了目前聚乳酸类生物降解材料在缓控释药物制剂中的主要问题,展望了其发展前景.     

药物洗脱支架载药层材料及其制备技术研究进展

支架内再狭窄多年来一直是制约冠心病介入治疗远期疗效的瓶颈,药物洗脱支架的出现为解决这一问题提供了有效手段,而药物洗脱支架制备的关键在于载药层的制备.针对载药层制备技术,包括支架的预处理、载药材料的选择、载药层的制备工艺以及载药层药物的释放机制进行了回顾与综合评述,并指出了药物洗脱支架栽药层材料及其制备技术的发展方向.     

海藻酸钠作为药物载体材料的研究进展

综述海藻酸钠作为药物载体材料的研究进展;依据国内外的文献报道来阐述海藻酸盐凝胶材料、海藻酸钠共混材料、海藻酸钠化学改性材料作为药物载体材料的研究进展;海藻酸钠作为药物载体材料有很广阔的应用前景.     

聚己内酯的应用研究进展

综述了聚己内酯的重要特性及在生物医药方面的研究进展,主要介绍了聚己内酯作为药物释放载体、组织工程支架材料等以及其他方面的应用研究.     

他克莫司-聚三亚甲基碳酸酯药物洗脱支架涂层研究

以表面溶蚀性可降解聚合物聚三亚甲基碳酸酯（PTMC）为载体,分别采用超声雾化喷涂技术和溶液浇注法制备了以PTMC为涂层载体的他克莫司药物洗脱支架和载药薄膜。傅里叶红外光谱（FT-IR）结果显示他克莫司分散在PTMC中。扫描电子显微镜观察支架撑开后的药物涂层保持连续均匀,没有开裂和剥落。他克莫司洗脱支架的药物释放行为与Weibull模型的相关性最高。体外血小板粘附和平滑肌粘附、增殖实验表明包载他克莫司的PTMC表面具有显著地抑制血小板粘附和平滑肌增生的作用。     

水溶性聚乙烯醇作为药物载体材料的应用研究

聚乙烯醇(PVA)是一种水溶性高分子聚合物,常用于眼用制剂、口服制剂、注射剂、微胶囊剂、透皮贴剂、缓释微球及纳米粒等药物载体材料的制备.介绍了水溶性聚乙烯醇材料的特性及型号,以及永溶性PVA作为药物载体材料在制剂及其它药学方面的应用,展望了PVA材料在药物载体材料方面的应用,指出了今后的发展方向和趋势.     

生物医用材料用于药物递送系统的研究进展

生物医用绿色载体材料因其独特的结构和优异的性能,被广泛应用于医药、医疗和食品等领域,并发挥着越来越多的作用。特别是生物医用载体材料用于药物递送系统,可用载体材料将抗癌药物包裹在内,靶向、缓释和控释递送药物至肿瘤部位,有效治疗癌症,并且避免对人体正常组织的毒副作用,生物医用材料载药微球已是当前的研究热点之一。主要论述了天然以及合成的生物医用载体材料,对目前新型医用载体的制备以及应用进行了介绍,并对目前抗癌药物载体存在的问题进行的归纳总结,对其研究方向也进行了展望。     

In vitro Study on a New High Nitrogen Nickel-free Austenitic Stainless Steel for Coronary Stents

Most commercialized coronary stents are made of 316L stainless steels due to its good combination of properties,and currently some new stents are made of cobalt-based alloy owing to its higher mechanical properties. However,the presence of high quantity of nickel and/or cobalt elements in these materials,which are known to trigger the toxic and allergic responses,has caused many concerns.Nickel-free austenitic stainless steels have been developed in order to solve these problems.In this paper,based on the development of a new Fe-Cr-Mn-Mo-N type high nitrogen nickel-free austenitic stainless steel,properties such as mechanical property,corrosion resistance in Hank s solution,and in vitro blood compatibility including the kinetic clotting time and the platelets adhesion,were investigated in comparison to the above two conventional materials,a 316L stainless steel and a Co-28Cr-6Mo alloy.The results showed that the new high nitrogen steel possessed better combination of mechanical properties,corrosion resistance and blood compatibility than those of 316L steel and the Co-28Cr-6Mo alloy,and can be a promising alternative material for manufacture of coronary stents.     

Measurement and Numerical Simulation of the Dilatation Behaviour of Coronary Stents

Experiments are carried out to examine the dilatation properties of metallic stents. Therefore a test rig has been developed. Also the dilatation behaviour of stents out of different materials are investigated. Additionally numerical simulations of dilatation are carried out. Because balloon expandable stent systems exist of the stent and a balloon catheter, the balloon catheter is examined before the investigation of the stent systems. The results show a reproducible and similar dilatation behaviour for all stents. Titanium as a material with an advanced biocompatibility shows advantages in the dilatation behaviour against the stainless steel stents. A qualitative equality between simulation and measurement of the dilatation behaviour can be noticed. The results indicate the possibility to numerically simulate and to optimise the dilatation behaviour by a combination of simulation and measurement. The preclinical measurement can be reduced to some prototypes.     

可生物降解镁合金血管支架管坯的材料制备及成形研究进展

对可生物降解镁合金血管支架的研究现状进行了综述。镁合金作为新型可降解物材料成为了研究热点,其中血管支架是其最有前景的应用方向之一。镁合金微细管材成形困难及镁合金血管支架腐蚀速率过快,是制约其大规模临床应用的2个主要因素。作者介绍了近期国内外的相关研究,包括改善镁合金力学性能,以及为提高成形极限采取的新成形方法,为提高镁合金耐腐蚀性而采取的各种处理方法等。     

Tamibarotene-loaded citric acid-crosslinked alkali-treated collagen matrix as a coating material for a drug-eluting stent

Abstract

Tamibarotene-loaded biodegradable matrices with antithrombogenic and drug-releasing properties were prepared in a crosslinking reaction between amino groups of alkali-treated collagen (AlCol) and active ester groups of trisuccinimidyl citrate. The resulting matrices were characterized by their residual amino group concentrations, swelling ratios and thermal, antithrombogenic and drug-releasing properties. It was clarified that the addition of tamibarotene does not inhibit matrix formation. After immersion in water, the swelling ratio of a matrix became lower than that prior to immersion. Thermal analysis indicated that AlCol interacted with tamibarotene. The addition of tamibarotene to the matrix did not influence the antithrombogenic property of the resulting matrix. A matrix with a high crosslinking density had a prolonged tamibarotene elution time. These results demonstrate that tamibarotene-loaded matrices have great potential as a coating material for drug-eluting stents.     

管材属性对血管支架行为及支架制造性能影响

对介入治疗血管支架所用薄壁管材属性进行了评述,系统研究了管材属性对血管支架行为和制造性能的影响,提出了评价血管支架用管材的关键属性和指标.     

Influence of design parameters on the mechanical behavior and porosity of braided fibrous stents

In spite of all innovations in stent design, commonly used metallic stents present several problems such as corrosion, infection and restenosis, leading to health complications or even death of patients. In this context, the present paper reports a systematic investigation on designing and development of 100% fiber based stents, which can eliminate or minimize the problems with existing metallic stents. For this purpose, braided stents were produced by varying different materials, structural and process parameters such as mono-filament type and diameter, braiding angle and mandrel diameter. The influence of these design parameters on mechanical behavior as well as stent's porosity was thoroughly investigated, and suitable parameters were selected for developing a stent with mechanical characteristics and porosity matching with the commercial stents. According to the experimental results, the best performance was achieved with a polyester stent designed with 0.27 mm monofilament diameter, braiding angle of 35° and mandrel diameter of 6 mm, providing similar properties to commercial Nitinol stents.     

Design,Characterization, and 3D Printing of Cardiovascular Stents with Zero Poisson’s Ratio in Longitudinal Deformation

Inherent drawbacks associated with drug-eluting stents have prompted the development of bioresorbable cardiovascular stents. Additive manufacturing (3-dimentional (3D) printing) has been widely applied in medical devices. In this study, we develop a novel screw extrusion-based 3D printing system with a new designed mini-screw extruder to fabricate stents. A stent with a zero Poisson’s ratio (ZPR) structure is designed, and a preliminary monofilament test is conducted to investigate appropriate fabrication parameters. 3D-printed stents with different geometric structures are fabricated and analyzed by observation of the surface morphology. An evaluation of the mechanical properties and a preliminary biological evaluation of 3D-printed stents with different parameters are carried out. In conclusion, the screw extrusion-based 3D printing system shows potential for customizable stent fabrication.     

Practicability and Limitations of Finite Element Simulation of the Dilation Behaviour of Coronary Stents

After first implantation of a metallic stent into cardiac vessels in 1986 stent implantation has become a standard technique for treatment of coronary heart disease. During implantation of balloon‐expandable stents, the structure of the stent undergoes high plastic deformation. Despite the fact, that stents are used for more than 15 years nearly no information about the mechanical and micro structural process during dilation are known. The present paper presents a detailed study and comparison of the experimental and the simulated expansion behaviour of metallic stents. Used material models are discussed and crystallographic details are presented. Dilation curves describe the behaviour of balloon‐expandable coronary stents. The dilation behaviour depends on both the materials properties and the design of the stent. A numerical simulation of the dilation process by means of FE is suitable. A comparison of the experimental measurement and the numerical simulation demonstrates, that a Cauchy stress‐strain material model should be used for numerical simulations. A local failure criterion is introduced, which considers void initiation as a criterion for mechanical failure.     

Anticorrosion and cytocompatibility behavior of MAO/PLLA modified magnesium alloy WE42

Recently, biodegradable magnesium alloys have been introduced in the field of cardiovascular stents to avoid the specific drawbacks of permanent metallic implants. However, the major obstacle of the clinical use of magnesium-based materials is their rapid corrosion rate. In this paper, a composite micro-arc oxidation/poly-l-lactic acid (MAO/PLLA) coating was fabricated on the surface of the magnesium alloy WE42 to improve its corrosion resistance and the cytocompatibility of the modified materials was also investigated for safety aim. In our study, the morphology of materials was analyzed by Scanning electron microscopy. Potentiodynamic polarization was used to evaluate the corrosion behavior of the samples and corrosion weight loss was used to demonstrate their degradation rate. Furthermore, we applied cytotoxicity test in testing the cytocompatibility of the modified samples. The results showed that the PLLA coating effectively sealed the microcracks and micropores on the surface of the MAO coating by physical interlocking to interfere the corrosion ions. The corrosion rate was decreased and the cyototoxicity test showed that the MAO/PLLA composite coating WE42 had good cytocompatibility.     

Electrochemical and microstructural studies of tantalum and its oxide films for biomedical applications in endovascular surgery

The most popular coronary stents are made of 316L stainless steel and self-expandable Nitinol. Nevertheless, Ta has already been used to make stents for endovascular surgery and may constitute a good alternative to the other materials because of its higher corrosion resistance and radio-opacity property, which may facilitate the follow-up of stent catheterization. The characterization of Ta and its natural passive oxide films has been performed in a 0.15 M NaCl solution (simulated body fluid – SBF) using anodic polarizations, electrochemical impedance spectroscopy and photoelectrochemical techniques. Changes in microstructure have been observed by atomic force microscopy (AFM). Polarization curves show the existence of a current density increase between 1.40 and 1.80 V. Bode complex plots show that some perturbation of the film occurred in this potential interval which may be associated with a decrease in polarization resistance, Rp, indicating that the film may be less resistant to corrosive attack. Mott–Schottky capacity measurements show that the density of donors, Nd, varies with polarization. The optical band gap, E _g , which is equal to 4.1 eV did not show variations in our experiments. The localized formation on the electrode surface, in the above potential interval of a Ta compound (possibly an oxide-hydroxide) was observed by AFM, and this may explain the appearance of the current density peak and capacity behavior at those potentials.