Björk Per, Thomsson Daniel, Mirzov Oleg, Wigenius Jens, Inganäs Olle, Scheblykin Ivan G
Biomolecular and Organic Electronics, Department of Physics, Chemistry, and Biology, Linköping University, 581 83 Linköping, Sweden.
Small. 2009 Jan;5(1):96-103. doi: 10.1002/smll.200800855.
The organization of conjugated polyelectrolytes (CPEs) interacting with biomolecules sets conditions for the biodetection of biological processes and identity, through the use of optical emission from the CPE. Herein, a well-defined CPE and its binding to DNA is studied. By using dynamic light scattering and circular dichroism spectroscopy, it is shown that the CPE forms a multimolecule ensemble in aqueous solution that is more than doubled in size when interacting with a small DNA chain, while single chains are evident in ethanol. The related changes in the fluorescence spectra upon polymer aggregation are assigned to oscillator strength redistribution between vibronic transitions in weakly coupled H-aggregates. An enhanced single-molecule spectroscopy technique that allows full control of excitation and emission light polarization is applied to combed and decorated lambdaDNA chains. It is found that the organization of combed CPE-lambdaDNA complexes (when dry on the surface) allows considerable variation of CPE distances and direction relative to the DNA chain. By analysis of the polarization data energy transfer between the polymer chains in individual complexes is confirmed and their sizes estimated.
共轭聚电解质（CPEs）与生物分子相互作用的组织方式，通过利用CPE的光发射，为生物过程和身份的生物检测设定了条件。在此，研究了一种定义明确的CPE及其与DNA的结合。通过动态光散射和圆二色光谱法表明，CPE在水溶液中形成多分子聚集体，与小DNA链相互作用时其尺寸增加一倍以上，而在乙醇中则以单链形式存在。聚合物聚集时荧光光谱的相关变化归因于弱耦合H-聚集体中振动跃迁之间的振子强度重新分布。一种增强的单分子光谱技术被应用于梳理和修饰的λDNA链，该技术可完全控制激发光和发射光的偏振。研究发现，梳理后的CPE-λDNA复合物（在表面干燥时）的组织方式使得CPE相对于DNA链的距离和方向有相当大的变化。通过对偏振数据的分析，证实了单个复合物中聚合物链之间的能量转移并估计了它们的大小。
