Oxidized polyethylene films for orienting polar molecules for linear dichroism spectroscopy.
Oxidized polyethylene films for orienting polar molecules for linear dichroism spectroscopy.
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DOI：
10.1039/c3an02322b
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发表时间：
2014-02
期刊：
影响因子：
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通讯作者：
K. Razmkhah;N. Chmel;M. Gibson;A. Rodger
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文献类型：
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作者：
K. Razmkhah;N. Chmel;M. Gibson;A. Rodger
几十年来，拉伸聚乙烯(PE)薄膜一直被用来定向小分子，方法是在其表面沉积溶液，并允许溶剂蒸发，使分析物吸收在聚合物薄膜上。然而，PE的非极性疏水性质是排列极性分子和生物样品的障碍。本文采用氧气等离子体对PE膜进行表面处理，以提高膜的表面亲水性。通过接触角测量和X射线光电子能谱对不同处理条件进行了评价。经处理的PE(OX)膜能够排列不同极性的分子，包括孕酮、1-丙二醛、4‘，6-二氨基-2-苯基吲哚(DAPI)和菲。通过一系列线性二向色性(LD)实验研究了每个分子的排列程度，并确定了电子跃迁矩的极化。首次确定了拉伸薄膜LD的最佳条件(如拉伸因子和样品浓度)。比较了PE(OX)膜与普通PE膜的对准能力。黄体酮在PE(OX)上的排列略好于PE(OX)。1-吡喃甲醛在两种不同薄膜上的取向不同，这使得这种低对称性分子的跃迁矩得以指定。DAPI(不与PE对齐)与PE(OX)对齐良好，使我们能够获得比以前用聚乙烯醇收集的更好的LD数据。对菲的排列、二聚体和高阶结构的形成进行了比以前更详细的研究，显示了在PE和PE(OX)膜上的各种组装。
Stretched polyethylene (PE) films have been used to orient small molecules for decades by depositing solutions on their surface and allowing the solvent to evaporate leaving the analyte absorbed on the polymer film. However, the non-polar hydrophobic nature of PE is an obstacle to aligning polar molecules and biological samples. In this work PE film was treated with oxygen plasma in order to increase surface hydrophilicity. Different treatment conditions were evaluated using contact angle measurement and X-ray photoelectron spectroscopy. Treated PE (PE(OX)) films are shown to be able to align molecules of different polarities including progesterone, 1-pyrenecarboxaldehyde, 4',6-diamidino-2-phenylindole (DAPI) and anthracene. The degree of alignment of each molecule was studied by running series of linear dichroism (LD) experiments and the polarizations of electronic transition moments were determined. For the first time optimal conditions (such as stretching factor and concentration of the sample) for stretched film LD were determined. PE(OX) aligning ability was compared to that of normal PE films. Progesterone showed a slightly better alignment on PE(OX) than PE. 1-Pyrenecarboxaldehyde oriented differently on the two different films which enabled transition moment assignment for this low symmetry molecule. DAPI (which does not align on PE) aligned well on PE(OX) and enabled us to obtain better LD data than had previously been collected with polyvinyl alcohol. Anthracene alignment and formation of dimers and higher order structures were studied in much more detail than previously possible, showing a variety of assemblies on PE and PE(OX) films.