DNA height in scanning force microscopy
DNA height in scanning force microscopy
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DOI：
10.1016/s0304-3991(03)00004-4
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发表时间：
2003-08-01
期刊：
影响因子：
2.2
通讯作者：
Baró, AM
中科院分区：
文献类型：
--
作者：
Moreno-Herrero, F;Colchero, J;Baró, AM
通过扫描探针显微镜测量的云母基质上吸附的DNA分子的高度总是小于理论直径。在本文中，我们表明，当在环境条件下成像时，分子通常浸入盐层中，用于将它们吸附到基材上。这一层扭曲了 DNA 高度的测量，是误差的主要来源，但不是唯一的来源。我们使用两种扫描力技术进行了不同的实验来研究这个问题：空气中的非接触敲击模式和水溶液中的跳跃模式，其中脱水现象被最小化。使用敲击模式测量空气中 DNA 的高度，结果显示高度为 0.7 +/- 0.2 nm。当嵌入分子的盐层被去除时，该值增加至 1.5 +/- 0.2 nm。当最大施加力为 300pN 时，水中的跳跃实验给出的值为 1.4 +/- 0.3 nm，在非常低的力下给出的值为 1.8 +/- 0.2 nm，这证实了盐层的去除。尽管如此，在我们所有的实验中，测得的 DNA 高度都小于理论值。我们的结果表明，尽管盐层的存在很重要，但由于尖端的加载力或与基底的相互作用而导致的一些样品变形也存在。 (C) 2003 Elsevier Science B.V. 保留所有权利。
The measured height of DNA molecules adsorbed on a mica substrate by scanning probe microscopy is always less than the theoretical diameter. In this paper we show that, when imaged in ambient conditions, the molecules are usually immersed in the salt layer used to adsorb them to the substrate. This layer distorts the measurement of DNA height and is the main source of error but not the only one. We have performed different experiments to study this problem using two scanning force techniques: non-contact tapping mode in air and jumping mode in aqueous solution, where the dehydration phenomena is minimized. Height measurements of DNA in air using tapping mode reveal a height of 0.7 +/- 0.2nm. This value increases up to 1.5 +/- 0.2nm when the salt layer, in which the molecules are embedded, is removed. Jumping experiments in water give a value of 1.4 +/- 0.3nm when the maximum applied force is 300pN and 1.8 +/- 0.2nm at very low forces, which confirms the removal of the salt layer. Still, in all our experiments, the measured height of the DNA is less than the theoretical value. Our results show that although the salt layer present is important, some sample deformation due to either the loading force of the tip or the interaction with the substrate is also present. (C) 2003 Elsevier Science B.V. All rights reserved.