Sandström Pär, Akerman Björn
Department of Chemistry and Bioscience, Chalmers University of Technology, Kemivägen 10, SE-412 96 Göteborg, Sweden.
Langmuir. 2004 May 11;20(10):4182-6. doi: 10.1021/la036263z.
Oligonucleotide-modified gold nanoparticles are used in various kinds of colorimetric DNA targeting biosensors and nanoparticle assembly techniques. Herein we focus on how the size of 13 nm gold colloids changes upon DNA modification. We have performed a series of electrophoresis experiments of particles modified both thiol specifically and nonspecifically with single- and double-stranded oligonucleotides of different lengths (12- and 25-mers). Both unmodified and DNA-modified particles migrated at constant velocity in different concentrations of Metaphor agarose gels. Linear Ferguson plots were obtained for all samples, and on the basis of the Ogston model approach, we present how the particle size increases in different amounts depending on the oligonucleotide length, secondary structure, and type of modification (specific or nonspecific). Thiol specifically modified particles obtain a thicker DNA layer since the oligonucleotides are only anchored to the particle in one end and thus stand up from the surface more compared to nonspecifically modified ones, where the oligonucleotides tend to lay more or less flat on the surface with multiple adsorption points. However the thickness of the DNA layer for the thiol specifically modified particles is smaller than the length of a corresponding stretched oligonucleotide, suggesting a flexibility of the thiol-bound strands allowing them to tilt relative to the particle surface.
寡核苷酸修饰的金纳米颗粒被用于各种比色法DNA靶向生物传感器和纳米颗粒组装技术中。在此，我们关注13纳米金胶体在DNA修饰后尺寸如何变化。我们对用不同长度（12聚体和25聚体）的单链和双链寡核苷酸进行了特异性和非特异性硫醇修饰的颗粒进行了一系列电泳实验。未修饰的颗粒和DNA修饰的颗粒在不同浓度的Metaphor琼脂糖凝胶中均以恒定速度迁移。所有样品均获得了线性弗格森图，并且基于奥格斯顿模型方法，我们展示了颗粒尺寸如何根据寡核苷酸长度、二级结构和修饰类型（特异性或非特异性）以不同程度增加。特异性硫醇修饰的颗粒获得了更厚的DNA层，因为寡核苷酸仅在一端锚定在颗粒上，因此与非特异性修饰的颗粒相比，从表面立起得更多，在非特异性修饰的颗粒中，寡核苷酸倾向于通过多个吸附点或多或少地平躺在表面上。然而，特异性硫醇修饰颗粒的DNA层厚度小于相应拉伸寡核苷酸的长度，这表明硫醇结合链具有柔韧性，使其能够相对于颗粒表面倾斜。
