Drug-eluting stents (DESs) are used to treat cardiovascular diseases such as atherosclerosis. The anti-proliferative drug released from the DES suppress the proliferation of smooth muscle cells and reduced in-stent restenosis. However, a burst release of the drug in the early stages and degradation morphology of the polymer coating represent major disadvantages, which might increase the incidence of in-stent restenosis and/or thrombosis under in vivo clinical studies. To solve these problems, in this study, a double-layer coating system composed of poly(lactide) (PLLA) bottom layer and poly(lactide-co-glycolide) (PLGA) top layer are used for the fabrication of DES. PLLA bottom layer was firstly coated on the metal surface followed by oxygen ion beam treatment. It was found that increasing the ion beam exposure time, increased the roughness of PLLA surface with a nanoscale pocket (or hole)-like structure. The top layer coating represented a mixture of PLGA and paclitaxel (PTX) with 5, 10, and 20% PTX contents. The coating was performed through ultrasonic spray technique, and the morphology showed not only a smooth and uniform surface but also no irregularities were observed at zero day. The drug release and degradation morphology for single-layer (PLGA/PTX) and double-layer (PLLA/PLGA/PTX) coatings were compared. The drug release from the double-layer stainless steel (SS) group showed a slower and controlled drug release for all PTX content samples as compared to single-layer SS group. Moreover, the degradation morphology of double-layer SS group presented a smoother and uniform surface after 12 weeks of degradation under physiological conditions. Therefore, an oxygen ion beam technique with double-layer coating system could effectively control the drug release, i.e., prevent initial burst drug release, and improve the degradation morphology of biodegradable polymer-based DESs.

中文翻译：

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具有改善的降解形态和受控药物释放的双层涂层药物洗脱支架

药物洗脱支架（DES）用于治疗心血管疾病，例如动脉粥样硬化。从DES释放出的抗增殖药抑制了平滑肌细胞的增殖并减少了支架内再狭窄。但是，药物的早期释放和聚合物涂层的降解形态是主要的缺点，在体内临床研究中，这可能会增加支架内再狭窄和/或血栓形成的发生率。为了解决这些问题，在本研究中，采用了一种由聚丙交酯（PLLA）底层和聚丙交酯共聚物组成的双层涂层系统。-乙交酯（PLGA）顶层用于制造DES。首先将PLLA底层涂覆在金属表面上，然后进行氧离子束处理。发现增加离子束暴露时间，增加了具有纳米级袋状（或孔状）结构的PLLA表面的粗糙度。顶层涂层代表PLGA和紫杉醇（PTX）的混合物，PTX含量为5、10和20％。通过超声喷涂技术进行涂覆，并且形态不仅显示出光滑且均匀的表面，而且在零天也没有观察到不规则性。比较了单层（PLGA / PTX）和双层（PLLA / PLGA / PTX）涂层的药物释放和降解形态。与单层SS组相比，双层不锈钢（SS）组的药物释放显示所有PTX含量样品的药物释放均较慢且受控。而且，在生理条件下降解12周后，双层SS组的降解形态呈现出更光滑且均匀的表面。因此，采用双层涂层系统的氧离子束技术可以有效地控制药物的释放，即，防止最初的突释药物释放，并改善可生物降解的聚合物基DES的降解形态。