CIRCULAR DNA-MOLECULES IMAGED IN AIR BY SCANNING FORCE MICROSCOPY
CIRCULAR DNA-MOLECULES IMAGED IN AIR BY SCANNING FORCE MICROSCOPY
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DOI：
10.1021/bi00116a005
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发表时间：
1992-01-14
期刊：
影响因子：
2.9
通讯作者：
KELLER, R
中科院分区：
文献类型：
--
作者：
BUSTAMANTE, C;VESENKA, J;KELLER, R
用扫描力显微镜（SFM）对空气中的DNA分子进行了常规和可重复的成像。将质粒DNA的环状分子沉积在红云母上，并在各种相对湿度下成像。在相关的实验中，还获得了大肠杆菌RNA聚合酶-DNA复合物的第一张图像。这是可能的，通过（1）使用具有10 nm或更小的一致曲率半径的特别改性的SFM尖端，以最小化由市售尖端的有限尺寸引入的图像失真量，（2）优化以稳定的方式将DNA分子存款和结合到云母表面的方法，和（3）小心控制样品湿度，以防止分子的溶剂化和通过扫描尖端或触针从表面分离。在空气中和存在残余湿度的情况下，通常可能存在几个纳牛顿范围内的接触力。图像的空间分辨率似乎由修改后的探针的曲率半径决定，该曲率半径可以直接从图像中DNA分子的表观宽度估计。
Routine and reproducible imaging of DNA molecules in air with the scanning force microscope (SFM) has been accomplished. Circular molecules of plasmid DNA were deposited onto red mica and imaged under various relative humidities. In related experiments, the first images of the Escherichia coli RNA polymerase-DNA complex have also been obtained. This has been possible by (1) the use of specially modified SFM tips with a consistent radius of curvature of 10 nm or less, to minimize the amount of image distortion introduced by the finite dimensions of commercially available tips, (2) the optimization of a method to deposit and bind DNA molecules to the mica surface in a stable fashion, and (3) careful control of the sample humidity, to prevent solvation of the molecules and detachment from the surface by the scanning tip or stylus. Contact forces in the range of a few nanonewtons are routinely possible in air and in the presence of residual humidity. The spatial resolution of the images appears determined by the radius of curvature of the modified styli, which can be estimated directly from the apparent widths of the DNA molecules in the images.