Center for Biomaterials, Korea Institute of Science and Technology, P.O. Box 131, Cheongryang, Seoul 130-650, Korea.
Langmuir. 2011 Dec 6;27(23):14232-9. doi: 10.1021/la2030318. Epub 2011 Nov 4.
A method of securing the adhesion of biodegradable polymer coating was investigated for drug-eluting metal stents, using surface-initiated ring-opening polymerization (SI-ROP) of L-lactide. Introduction of oligolactide on the stainless steel (SS) surface was successful and the thickness of the oligolactide grafts remained on the nanometer scale, as determined by ellipsometry. The presence of an oligolactide graft was also identified using attenuated total reflection-Fourier transform infrared (ATR-FTIR) and electron spectroscopy for chemical analysis (ESCA). On top of the grafts, poly(D,L-lactide-co-glycolide) (PLGA) coating was carried out on different substrates such as SS control, plasma-treated SS, and lactide-grafted (referred to as a nanocoupled) SS using electrospraying. When the adhesion forces were measured with a scratch tester, the nanocoupled SS showed the strongest interfacial adhesion between polymer coating layer and metal substrate. The outcome of the peel-off test was also consistent with the result of the scratch test. When degradation behavior of the polymer coating in vitro was examined for up to 4 weeks in a continuous fluid flow, the SEM images demonstrated that polymer degradation was obvious due to hydration and swelling of the polymer matrix. Although the matrix completely disappeared after 4 weeks for SS control and plasma-treated substrates, the nanocoupled SS was persistent with some polymer matrix. In addition, the release profiles of SRL-loaded PLGA coating appeared slightly different between control and nanocoupled groups. This work suggested that the concept of nanocoupling remarkably improved the interfacial adhesion stability between metal surface and polymer layer and controlled drug release, and showed the feasibility of drug-eluting stents.
采用表面引发开环聚合（SI-ROP）法制备了可降解聚合物涂层，以提高载药金属支架的附着力。成功地将低聚丙交酯接枝到不锈钢（SS）表面，通过椭偏仪测定，低聚丙交酯接枝的厚度保持在纳米级。利用衰减全反射傅里叶变换红外（ATR-FTIR）和电子能谱（ESCA）也可以检测到低聚丙交酯的存在。在接枝物的顶部，通过静电喷涂在不同的基底上进行了聚（D，L-丙交酯-co-乙交酯）（PLGA）涂层，如 SS 对照、等离子体处理 SS 和接枝丙交酯（称为纳米偶联）SS。用划痕测试仪测量附着力时，纳米偶联 SS 显示出聚合物涂层和金属基底之间最强的界面附着力。剥离试验的结果也与划痕试验的结果一致。在体外连续流体流动中对聚合物涂层的降解行为进行了长达 4 周的研究，SEM 图像表明聚合物由于聚合物基质的水合和溶胀而明显降解。尽管在 4 周后 SS 对照和等离子体处理的基底上聚合物基质完全消失，但纳米偶联 SS 仍有一些聚合物基质存在。此外，SRL 负载的 PLGA 涂层的释放曲线在对照组和纳米偶联组之间也略有不同。这项工作表明，纳米偶联的概念显著提高了金属表面和聚合物层之间的界面附着稳定性，控制了药物释放，并展示了载药支架的可行性。
