Institute of Physics, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland.
Phys Rev Lett. 2010 Mar 5;104(9):095501. doi: 10.1103/PhysRevLett.104.095501. Epub 2010 Mar 2.
Radiation damage is considered to be the major problem that still prevents imaging an individual biological molecule for structural analysis. So far, all known mapping techniques using sufficient short wavelength radiation, be it x rays or high energy electrons, circumvent this problem by averaging over many molecules. Averaging, however, leaves conformational details uncovered. Even the anticipated use of ultrashort but extremely bright x-ray bursts of a free electron laser shall afford averaging over 10{6} molecules to arrive at atomic resolution. Here, we present direct experimental evidence for nondestructive imaging of individual DNA molecules. In fact, we show that DNA withstands coherent low energy electron radiation with deBroglie wavelength in the Angstrom regime despite a vast dose of 10{8} electrons/nm{2} accumulated over more than one hour.
辐射损伤被认为是仍然阻止对单个生物分子进行结构分析成像的主要问题。到目前为止，所有已知的使用足够短波长辐射的映射技术，无论是 X 射线还是高能电子，都通过对许多分子进行平均来规避这个问题。然而，平均化会掩盖构象细节。即使预期使用自由电子激光的超短但极其明亮的 X 射线爆发，也只能对 10{6}个分子进行平均化，以达到原子分辨率。在这里，我们提供了直接的实验证据，证明可以对单个 DNA 分子进行非破坏性成像。事实上，我们表明，尽管在一个多小时内累积了超过 10{8}个电子/nm{2}的巨大剂量，但 DNA 能够抵抗相干低能电子辐射，其德布罗意波长在埃范围内。
