The electrostatic complexes of double-stranded deoxyribonucleic acid (dsDNA) and a cationic conjugated polyelectrolyte, poly(4,4′-(1,4-phenylene)bis(2,6-diphenylpyridinium))-co-para-biphenylene ditosylates} (PPT), were investigated by spectral methods. The binding constant of PPT with calf thymus DNA (ctDNA) is estimated to be 9.3 × 105 M−1, which was determined by UV-vis spectral titration. Fluorescence emission of PPT in phosphate buffer solutions (5.0 μM) can be drastically quenched to about one-fourth of its original intensity in the presence of a trace amount (0.28 μM) of ctDNA with a large Stern–Volmer constant (KSV = 8.79 × 106 M−1). The fluorescence quenching efficiency is related to the target concentration, which allows the quantitative detection of the target sequence in a sample. A linear detection range from 1.5 to 280 nM was obtained under the optimized experimental conditions with a detection limit down to the 10−9 M range. Furthermore, strong electrostatic attraction may be the main driving force for PPT/ctDNA binding, which was proposed according to the results of circular dichroism and melting transition study of ctDNA in the presence of PPT. This investigation provides an insight into designing a novel conjugated polyelectrolyte for biomolecular sensing.
通过光谱方法研究了双链
脱氧核糖核酸(dsDNA)与阳离子共轭聚电解质聚(4,4'-(1,4-苯二基)双(
2,6-二苯基吡啶鎓))-共-对
联苯二
甲磺酸盐}(P
PT)的静电复合物。通过紫外-可见光谱滴定法测定,P
PT与小牛胸腺DNA(ctDNA)的结合常数估计为9.3 × 105 M−1。在
磷酸盐缓冲液(5.0 μM)中,P
PT的荧光发射强度在存在痕量(0.28 μM)ctDNA的情况下可以急剧下降至原来的约四分之一,其Stern-Volmer常数(KSV)为8.79 × 106 M−1。荧光猝灭效率与目标浓度相关,这使得可以对样品中的目标序列进行定量检测。在优化的实验条件下,获得了从1.5到280 nM的线性检测范围,检测限可达到10−9 M范围。此外,根据圆二色性和熔融转变研究结果,强烈静电吸引力可能是P
PT/ctDNA结合的主要驱动力。这项研究为设计新型共轭聚电解质用于
生物分子传感提供了见解。