Laboratory of Organic Chemistry, Wageningen University , Dreijenplein 8, 6703 HB Wageningen, The Netherlands.
Langmuir. 2011 Mar 15;27(6):2587-94. doi: 10.1021/la104657c. Epub 2011 Feb 3.
Zwitterionic poly(sulfobetaine acrylamide) (SBMAA) brushes were grafted from silicon-rich silicon nitride (SixN4, x > 3) surfaces by atom transfer radical polymerization (ATRP) and studied in protein adsorption experiments. To this aim ATRP initiators were immobilized onto SixN4 through stable Si-C linkages via three consecutive reactions. A UV-induced reaction of 1,2-epoxy-9-decene with hydrogen-terminated SixN4 surfaces was followed by conversion of the epoxide with 1,2-ethylenediamine resulting in primary and secondary amine-terminated surfaces. A reaction with 2-bromoisobutyryl bromide led to ATRP initiator-covered surfaces. Zwitterionic polymer brushes of SBMAA were grown from these initiator-coated surfaces (thickness ∼30 nm), and the polymer-coated surfaces were characterized in detail by static water contact angle measurements, X-ray photoelectron spectroscopy (XPS), and an atomic force microscope (AFM). The adsorption of proteins onto zwitterionic polymer coated surfaces was evaluated by in situ reflectometry, using a fibrinogen (FIB) solution of 0.1 g·L(-1), and compared to hexadecyl-coated SixN4 surfaces (C16-SixN4), uncoated air-based plasma oxidized SixN4 surfaces (SiOy-SixN4), and hexa(ethylene oxide)-coated SixN4 surfaces (EO6-SixN4). Excellent protein repellence (>99%) was observed for these zwitterionic polymer-coated SixN4 surfaces during exposure to FIB solution as compared to C16-SixN4 surfaces. Furthermore, the stability of these zwitterionic polymer-coated SixN4 surfaces was surveyed by exposing the surfaces for 1 week to phosphate buffered saline (PBS) solution at room temperature. The zwitterionic polymer-coated SixN4 surfaces before and after exposure to PBS solution were characterized by XPS, AFM, and water contact angle measurements, and their protein-repelling properties were evaluated by reflectometry. After exposure to PBS solution, the zwitterionic polymer coating remained intact, and its thickness was unchanged within experimental error. No hydrolysis was observed for the zwitterionic polymer after 1 week exposure to PBS solution, and the surfaces still repelled 98% FIB as compared to C16-SixN4 surfaces, demonstrating the long-term efficiency of these easily prepared surface coatings.
聚（磺酸甜菜碱丙烯酰胺）（SBMAA）两性离子刷通过原子转移自由基聚合（ATRP）接枝到富硅氮化硅（SixN4，x＞3）表面，并在蛋白质吸附实验中进行了研究。为此，通过三个连续的反应，将 ATRP 引发剂通过稳定的 Si-C 键固定在 SixN4 上。首先，通过 1,2-环氧-9-癸烯与氢封端的 SixN4 表面的 UV 诱导反应，然后用 1,2-乙二胺将环氧化物转化为伯胺和仲胺封端的表面。然后用 2-溴异丁酰溴进行反应，得到 ATRP 引发剂覆盖的表面。从这些引发剂涂覆的表面（厚度约 30nm）生长出两性离子聚合物刷 SBMAA，并通过静态水接触角测量、X 射线光电子能谱（XPS）和原子力显微镜（AFM）详细表征聚合物涂覆的表面。通过原位反射计评估蛋白质在两性离子聚合物涂覆表面上的吸附，使用浓度为 0.1g·L(-1)的纤维蛋白原（FIB）溶液，并与十六烷基涂覆的 SixN4 表面（C16-SixN4）、未涂覆的空气等离子体氧化的 SixN4 表面（SiOy-SixN4）和六（环氧乙烷）涂覆的 SixN4 表面（EO6-SixN4）进行比较。与 C16-SixN4 表面相比，这些两性离子聚合物涂覆的 SixN4 表面在暴露于 FIB 溶液时表现出优异的蛋白质排斥性（＞99%）。此外，通过将表面在室温下暴露于磷酸盐缓冲盐水（PBS）溶液中一周来研究这些两性离子聚合物涂覆的 SixN4 表面的稳定性。通过 XPS、AFM 和水接触角测量对暴露于 PBS 溶液前后的两性离子聚合物涂覆的 SixN4 表面进行了表征，并通过反射计评估了其蛋白质排斥性能。暴露于 PBS 溶液后，两性离子聚合物涂层保持完整，其厚度在实验误差范围内没有变化。暴露于 PBS 溶液一周后，未观察到两性离子聚合物发生水解，与 C16-SixN4 表面相比，其仍排斥 98%的 FIB，表明这些易于制备的表面涂层具有长期效率。
