Bedair Tarek M, Cho Youngjin, Joung Yoon Ki, Han Dong Keun
Center for Biomaterials, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul 136-791, Republic of Korea; Department of Biomedical Engineering, Korea University of Science and Technology, 113 Gwahangno, Yuseong-gu, Daejeon 305-333, Republic of Korea; Chemistry Department, Faculty of Science, Minia University, El-Minia 61519, Egypt.
Center for Biomaterials, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul 136-791, Republic of Korea.
Colloids Surf B Biointerfaces. 2014 Oct 1;122:808-817. doi: 10.1016/j.colsurfb.2014.08.025. Epub 2014 Aug 27.
Metal-based drug-eluting stents (DESs) have severe drawbacks such as peeling-off and cracking of the coated polymer. To prevent the fracture of polymer-coated layer and improve the durability of DES, poly(l-lactide) (PLLA) brushes were synthesized onto cobalt-chromium (Co-Cr or CC) surface through atom transfer radical polymerization (ATRP) of 2-hydroxyethylmethacrylate (HEMA) followed by surface-initiated ring opening polymerization (SI-ROP) of l-lactide. The polymer brushes were then characterized by attenuated total reflection-Fourier transform infrared (ATR-FTIR), water contact angle, ellipsometry, X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and scanning electron microscopy (SEM). All of the unmodified and modified Co-Cr surfaces were coated with a matrix of poly(d,l-lactide) (PDLLA) and sirolimus (SRL). The in vitro drug release profile was measured for 70 days. The PLLA-modified Co-Cr showed a biphasic release pattern in the initial burst followed by a slow release. On the other hand, the unmodified Co-Cr showed fast drug release and detachment of the coated polymer layer due to the instability of the polymer layer on Co-Cr surface. In comparison, the PLLA-modified Co-Cr preserved a uniform coating without detachment even after 6 weeks of degradation test. The platelet morphology and low density of platelet adhered on the modified layer and the SRL-in-PDLLA coated Co-Cr surfaces demonstrated that these samples would be blood compatible. Therefore, the introduction of PLLA brush onto Co-Cr surface is proved to dramatically improve the durability of the coating layer, and it is a promising strategy to prevent the coating defects found in DESs.
金属基药物洗脱支架（DESs）存在严重缺点，如涂层聚合物的剥落和开裂。为防止聚合物涂层断裂并提高DES的耐久性，通过甲基丙烯酸2-羟乙酯（HEMA）的原子转移自由基聚合（ATRP），随后进行丙交酯的表面引发开环聚合（SI-ROP），在钴铬（Co-Cr或CC）表面合成了聚（L-丙交酯）（PLLA）刷。然后通过衰减全反射傅里叶变换红外光谱（ATR-FTIR）、水接触角、椭偏仪、X射线光电子能谱（XPS）、原子力显微镜（AFM）和扫描电子显微镜（SEM）对聚合物刷进行表征。所有未改性和改性的Co-Cr表面均涂覆有聚（D，L-丙交酯）（PDLLA）和西罗莫司（SRL）的基质。测量了70天的体外药物释放曲线。PLLA改性的Co-Cr在初始突释后呈现双相释放模式，随后缓慢释放。另一方面，未改性的Co-Cr由于聚合物层在Co-Cr表面的不稳定性而表现出快速药物释放和涂层聚合物层的脱落。相比之下，即使经过6周的降解测试，PLLA改性的Co-Cr仍保持均匀涂层而无脱落。血小板形态以及粘附在改性层和SRL-PDLLA涂层Co-Cr表面上的血小板低密度表明这些样品具有血液相容性。因此，可以证明在Co-Cr表面引入PLLA刷可显著提高涂层的耐久性，这是防止DES中发现的涂层缺陷的一种有前景的策略。
