Al Attar Hameed A, Monkman Andy P
Organic Electroactive Materials Research Group, Department of Physics, University of Durham, South Road, Durham DH1 3LE, United Kingdom.
Biomacromolecules. 2009 May 11;10(5):1077-83. doi: 10.1021/bm801194n.
Fluorescence resonance energy transfer (FRET) between water-soluble conjugated polymer, poly-(9,9-bis(6'-N,N,N-trimethylammonium)-hexyl-fluorene phenylene) bromide, and ssDNA's labeled with four different types of dyes (Pacific-blue, Alexa-fluor 430, Fluorescein, and ROX) has been investigated. The effect of spectral overlap and Stokes-shift on the efficiency and properties of FRET were studied. In the DNA sequence detection technique that using cationic conductive polymer and the negatively charged DNA the electrostatic interaction leads to strong aggregation. The effective concentration of these aggregates is quite high leading to strong self-absorption. In this case, labeling with small Stokes shift dyes shows a strong output emission limitation even in extremely dilute system. The steady state fluorescence quenching of the CCP by FRET reveals that the competition between FRET and self-absorption plays a major role when accounting for the FRET ratio. Time-resolved fluorescence lifetime analysis was carried out to measure the energy transfer between the donor and the acceptor excluding self-absorption and quenching by ground-state complex formation. Time-resolved analysis indicates only around 30% of the total CCP excited-state population is quenched by FRET, whereas 55% is quenched by the DNA/buffer solution.
研究了水溶性共轭聚合物聚（9,9-双（6'-N，N，N-三甲基铵）-己基芴亚苯基）溴与标记有四种不同类型染料（太平洋蓝、Alexa-fluor 430、荧光素和ROX）的单链DNA之间的荧光共振能量转移（FRET）。研究了光谱重叠和斯托克斯位移对FRET效率和性质的影响。在使用阳离子导电聚合物和带负电荷的DNA的DNA序列检测技术中，静电相互作用导致强烈聚集。这些聚集体的有效浓度相当高，导致强烈的自吸收。在这种情况下，即使在极稀的体系中，用小斯托克斯位移染料标记也显示出强烈的输出发射限制。通过FRET对CCP进行的稳态荧光猝灭表明，在考虑FRET比率时，FRET与自吸收之间的竞争起主要作用。进行了时间分辨荧光寿命分析，以测量供体和受体之间的能量转移，排除了自吸收和基态复合物形成引起的猝灭。时间分辨分析表明，CCP激发态总群体中只有约30%通过FRET猝灭，而55%通过DNA/缓冲溶液猝灭。
