可降解血管支架用镁合金表面壳聚糖及其衍生物涂层的制备与性能研究

发布时间：2018-04-28 20:26

本文选题：可降解心血管支架 + 镁合金　；参考：《郑州大学》2012年硕士论文

【摘要】：目前,临床应用的心血管支架均是不可降解的,作为异物在人体内的长期存在引起了诸如血管再狭窄、形成血栓等一系列的问题,因此可降解支架的研究引起了广泛关注。镁合金具有优良的综合力学性能和生物相容性,并且能在人体内降解,镁离子也是人体所必须的离子,是作为可降解心血管支架的理想材料。但是镁合金耐腐蚀性能很差,在体内降解过快,有效服役期过短,不能满足临床要求,因此改善镁合金的耐腐蚀性能显得尤为重要。壳聚糖是一种具有优良生物相容性的可降解天然高分子材料,已经被广泛的应用于生物医药领域,通过对其进行磺化处理能得到类肝素物质,此物质拥有非常好的抗凝血性能,能有效地解决血管再狭窄和血栓形成的问题。本文利用浸涂法在镁合金表面制备壳聚糖和磺化壳聚糖涂层,以及复合涂层,重点研究了涂层的表面特性及通过各种处理后镁合金在模拟体液中的耐腐蚀性能。实验表明,不同浓度的壳聚糖溶液粘度不同,在镁合金表面制备的壳聚糖涂层的致密度和表面平整度等不同,浓度0.5%的壳聚糖溶液比较稀,形成的膜致密度较差,表面气孔较多较大,容易产生微电池效应；浓度1.5%的壳聚糖溶液粘度大,形成的涂层表面平整度差,溶胀率大,容易产生脱落；浓度为1.0%的壳聚糖溶液形成的涂层致密平整,综合性能好,对镁合金的保护作用明显,可以通过改变浸涂次数来控制涂层厚度,浸涂3、5和7次得到的涂层的厚度分别为70μm、85μm和100μm。镁合金活化后,能增大涂层与基体的结合面积,减弱酸性涂层和基体的析氢反应,并引入大量活性-OH,从而增强结合强度,改善镁合金的耐腐蚀性能,活化消耗一定量的基体材料,因此控制活化的程度至关重要。实验表明,在镁合金表面先形成一层偶联剂涂层,偶联剂与镁合金表面形成Si-O共价键,从而增强结合强度。与利用无水乙醇为溶剂的硅烷偶联剂相比,去离子水为溶剂的硅烷偶联剂表现出更好的性能,但是会引起涂层较大面积的脱落,以乙醇为溶剂的偶联剂溶液产生的膜有优良的综合性能,预先进行活化处理后,能提供更多的接触面积和羟基。对镁合金进行交联处理,能够得到表面平整度很高的涂层,结合强度也大大提高,因为戊二醛中的醛基与壳聚糖中的氨基形成—C=N—键,使壳聚糖分子链相互结合成网状结构,溶胀率大大减小,减弱了由于溶胀引起的涂层脱落,壳聚糖膜的交联在一定程度上增加了镁合金的丝状腐蚀,且会影响到壳聚糖的活性,因此戊二醛的加入比例应该严格控制。在壳聚糖上面接枝磺酸基,磺酸基有吸附金属离子的倾向,相当于在壳聚糖涂层上分布着很多吸附点,能一定程度的增强结合强度,改善耐腐蚀性能。由红外光谱可知磺化壳聚糖的结构与肝素的结构非常相似,在波数804.2cm-1和1224.6cm-1处均出现明显的峰,说明在3,6位都成功接枝了磺酸基团,已被证实有很好的抗凝血性能。壳聚糖/磺化壳聚糖层层自组装膜是利用两种化合物带有不同的电荷而产生的静电力及分子链缠绕为结膜动力,在保持磺化壳聚糖好的抗凝性能的同时,还能极大的改善镁合金的抗腐蚀性能,其开路电位达到-0.9V左右,在模拟体液中浸泡120h对其pH值影响最大不超过0.4,体现出了优越的保护性能。材料的亲水性越好,其抗凝血性能越好。单纯的壳聚糖膜的亲水性不好,接触角为83°,对镁合金表面进行偶联、交联处理后均对壳聚糖膜亲水性有一定的改善作用,接触角分别为76.5°和52.5°,对壳聚糖进行磺化改性,制成的磺化壳聚糖膜有很好的亲水性,接触角为27°,壳聚糖/磺化壳聚糖层层自组装膜的接触角为57°。
[Abstract]:The present invention relates to a degradable natural polymer material with excellent biocompatibility , which has excellent comprehensive mechanical property and biocompatibility , and can be used as ideal material for degradable cardiovascular stent .

The results showed that different concentration of chitosan solution had different viscosity , the density of chitosan coating prepared on the surface of magnesium alloy was different , and the concentration of chitosan solution was 0.5 % .
the viscosity of the chitosan solution with the concentration of 1.5 percent is large , the surface smoothness of the formed coating is poor , the swelling rate is large , and the chitosan solution is easy to generate and fall off ;
The coating prepared by chitosan solution with the concentration of 1.0 % is compact and flat , the comprehensive performance is good , the protective effect on the magnesium alloy is obvious , the thickness of the coating can be controlled by changing the number of dip coating , and the thickness of the coating obtained by dip coating 3 , 5 and 7 times is 70 . m u.m , 85 . m u.m and 100 . m

After the magnesium alloy is activated , the bonding area of the coating and the substrate can be increased , the hydrogen evolution reaction of the acid coating and the substrate is weakened , and a large amount of active - OH is introduced , so that the bonding strength is enhanced , the corrosion resistance of the magnesium alloy can be improved , and a certain amount of matrix material is consumed , so that the degree of activation is controlled .

Compared with the silane coupling agent using absolute ethyl alcohol as solvent , the silane coupling agent with deionized water as solvent shows better performance , but it can cause the coating to fall off , and the film produced by the coupling agent solution with ethanol as solvent has excellent comprehensive performance , and can provide more contact area and hydroxyl group after the activation treatment is carried out in advance .

the crosslinking treatment of the magnesium alloy can obtain the coating with high surface flatness and greatly improve the bonding strength ; because the aldehyde group in the glutaraldehyde and the amino group in the chitosan form - C = N - bond , the chitosan molecular chains are combined into a net structure , the swelling rate is greatly reduced , the silk corrosion of the magnesium alloy is increased to a certain extent , and the crosslinking of the chitosan film can influence the activity of the chitosan , so that the adding proportion of glutaraldehyde should be strictly controlled .

The results show that the structure of sulfonated chitosan is very similar to that of heparin , which shows that the structure of sulfonated chitosan is very similar to the structure of heparin . It shows that the structure of sulfonated chitosan is very similar to the structure of heparin .

The chitosan / sulfonated chitosan layer self - assembly film is characterized by that the electrostatic force and the molecular chain generated by the chitosan / sulfonated chitosan layer self - assembly film are wound into conjunctival power by using two compounds with different electric charges , and the corrosion resistance performance of the magnesium alloy can be greatly improved while maintaining the anti - coagulation property of the sulfonated chitosan , and the open - circuit potential of the chitosan / sulfonated chitosan layer self - assembly film is about - 0.9V , and the influence on the pH value of the chitosan / sulfonated chitosan layer self - assembly film is not more than 0.4 , and the excellent protection performance is shown .

The better the hydrophilicity of the material , the better the anticoagulant properties . The hydrophilic property of the chitosan membrane was not good , the contact angle was 83 掳 , and the surface of the magnesium alloy was coupled . After crosslinking treatment , the hydrophilicity of chitosan membrane was improved . The contact angle was 76.5 掳 and 52.5 掳 , and the contact angle was 76.5 掳 and 52.5 掳 respectively . The sulfonated chitosan membrane prepared by sulfonation modified the chitosan membrane has a good hydrophilicity . The contact angle is 27 掳 . The contact angle of chitosan / sulfonated chitosan layer self - assembly film is 57 掳 .

【学位授予单位】：郑州大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：R318.08

【参考文献】