Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, Indiana 46556, USA.
Biomicrofluidics. 2012 Jun;6(2):24116-2411612. doi: 10.1063/1.4710998. Epub 2012 May 1.
Effective manipulation and understanding of the structural and dynamic behaviors of a single polyelectrolyte (PE) under alternating current (AC) electric fields are of great scientific and technological importance because of its intimate relevance to emerging bionanotechnology. In this work, we employ fluorescence correlation spectroscopy (FCS) to study the conformational and AC-electrokinetic behaviors of a model annealed PE, poly(2-vinyl pyridine) (P2VP) under both spatially uniform and non-uniform AC fields at a single molecule level. Under spatially uniform AC-fields, we observe a gradual and continuous coil-to-globule conformational transition (CGT) of single P2VP at varied AC-frequency when a critical AC-field strength is exceeded, in contrast to the pH-induced abrupt CGT in the absence of AC-fields. On the contrary, under spatially non-uniform AC-fields, we observe field-driven net flow and accumulation of P2VP near high AC-field regions due to combined AC electro-osmosis and dielectrophoresis but surprisingly no conformational change. Thus, distinct AC-electric polarization effect on single annealed PE subject to AC-field homogeneity is suggested.
有效操纵和理解单链聚电解质（PE）在交流（AC）电场下的结构和动态行为具有重要的科学和技术意义，因为它与新兴的生物纳米技术密切相关。在这项工作中，我们采用荧光相关光谱（FCS）技术在单分子水平上研究了模型退火聚电解质聚（2-乙烯基吡啶）（P2VP）在空间均匀和非均匀 AC 场下的构象和 AC 电动行为。在空间均匀的 AC 场下，当超过临界 AC 场强度时，我们观察到单 P2VP 的逐渐连续的从螺旋到球的构象转变（CGT），而在不存在 AC 场的情况下，pH 诱导的 CGT 是突然发生的。相反，在空间非均匀的 AC 场下，由于 AC 电渗流和介电泳的共同作用，我们观察到 P2VP 在高 AC 场区域附近的场驱动净流动和积累，但令人惊讶的是没有构象变化。因此，建议对受 AC 场均匀性影响的单链退火 PE 施加不同的 AC 电场极化效应。
