Hemocompatibility of zinc-calcium-phosphate coating on the surface of AZ31 magnesium alloy in vitro

doi:10.3969/j.issn.2095-4344.2016.25.011

Abstract

Abstract:

BACKGROUND: In our previous studies, zinc-calcium-phosphate (Zn-Ca-P) coating has been successfully prepared on the surface of AZ31 magnesium alloy, which improves the corrosion resistance of the alloy.

OBJECTIVE: To analyze the hemocompatibility of Zn-Ca-P coated AZ31 magnesium alloy in vitro.

METHODS: Zn-Ca-P coating was prepared on the surface of AZ31 magnesium alloy using chemical transformation. Afterwards, the characteristics of the Zn-Ca-P coating were investigated using scanning electron microscope, and X-ray diffraction analyzed its components. Besides, hemocompatibility in vitro was evaluated by platelet adhesion assay, dynamic clotting time test and hemolysis test.

RESULTS AND CONCLUSION: Under scanning electron microscope, a flower-like coating was formed ont surface of the AZ31 magnesium alloy, with the main chemical component of insoluble phosphates Zn₃(PO4)₂•4H₂O. And some round distortionless blood platelets adhered to the surface of AZ31 magnesium alloy, with no pseudopodia. In dynamic clotting time test, the long curve of Zn-Ca-P coating tended to descend indicating better anticoagulant activity. And the hemolysis rate was below 5%. In conclusion, Zn-Ca-P coating has good hemocompatibility in vitro.

中国组织工程研究杂志出版内容重点：生物材料；骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性；组织工程

Key words: Alloys, Materials Testing, Tissue Engineering

CLC Number:

R318

Zou Yu-hong, Chen Yue, Hu Min, Wang Qing-zhao, Zeng Rong-chang. Hemocompatibility of zinc-calcium-phosphate coating on the surface of AZ31 magnesium alloy in vitro[J]. Chinese Journal of Tissue Engineering Research, 2016, 20(25): 3720-3725.

Figures/Tables 4

2.3 体外动态凝血时间实验结果体外动态凝血时间可以间接检测内源性凝血因子被激活的程度，判断材料抗内源性凝血的能力[42]，反映血液在材料表面的凝固趋势和凝血时间的长短。血液与材料接触连续增加的时间段内测定冲洗液的吸光度值越高，材料的体外动态凝血时间曲线越平缓，说明材料与血液接触后凝血因子被激活的程度越低，材料的血液相容性越好。为了比较不同材料的抗凝血性能，人为定义纵坐标吸光度值为 0.100 时的时间为材料的凝血时间。 AZ31镁合金比含Zn-Ca-P涂层AZ31镁合金的动态凝血曲线下降陡峭，与血液接触50 min时，AZ31镁合金冲洗液吸光值达到0.1，凝血时间为50 min；含Zn-Ca-P涂层AZ31镁合金直到120 min吸光值仍未达到0.1，见图4，说明含Zn-Ca-P涂层镁合金的凝血因子被激活的程度低，因此证明Zn-Ca-P涂层后的AZ31镁合金血液相容性更好。 2.4 溶血实验结果溶血实验是评价材料血液相容性的常用指标，血液相容性好的医用材料应具有较低的溶血率(小于5%)[43-44]。实验中以测定545 nm波长处的吸光度值来计算溶血率。 AZ31镁合金的溶血率为(18.67±0.84)%，远远超出医用材料所规定的溶血要求；含Zn-Ca-P涂层AZ31镁合金的溶血率为(4.47±0.13)%，小于5%，满足对生物材料的溶血率要求。由此可知，经过Zn-Ca-P涂层后AZ31镁合金的溶血率降低明显，血液相容性较好。对于AZ31镁合金处理前后溶血率的变化，分析机制可能为：未进行表面处理的AZ31镁合金和血液接触后，材料局部腐蚀，产生的镁离子，提高了血液的渗透压，导致红细胞膜的破裂，造成溶血。当对AZ31镁合金进行Zn-Ca-P涂层后，AZ31镁合金的抗腐蚀性能显著提高，当其和血液相接触时，材料的降解减慢，进入血液的镁离子减少，红细胞的破裂减少，溶血率下降。 "

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