Signal enhancement and Patterson-search phasing for high-spatial-resolution coherent X-ray diffraction imaging of biological objects.
Signal enhancement and Patterson-search phasing for high-spatial-resolution coherent X-ray diffraction imaging of biological objects.
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DOI：
10.1038/srep08074
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发表时间：
2015-01-28
影响因子：
4.6
通讯作者：
Yonekura K
中科院分区：
文献类型：
--
作者：
Takayama Y;Maki-Yonekura S;Oroguchi T;Nakasako M;Yonekura K
近十年来，相干x射线衍射成像已被证明可以揭示整个生物细胞和细胞器的内部结构。然而，由于生物样品散射能力差，空间分辨率限制在几十纳米。挑战在于从具有低信噪比和不可测量的最低分辨率数据的实验衍射图案中恢复正确的相位信息。在这里，我们提出了一种通过增强衍射信号和鲁棒相位来扩展空间分辨率的方法。生物物体发出的弱衍射信号被分散的胶体金粒子发出的强波干扰而增强。利用Patterson分析确定的金颗粒位置作为初始相位，极大地提高了迭代相位检索图像重建的可靠性和收敛性。基于当前实验的一组计算表明，分辨率提高了两倍或更多。
In this decade coherent X-ray diffraction imaging has been demonstrated to reveal internal structures of whole biological cells and organelles. However, the spatial resolution is limited to several tens of nanometers due to the poor scattering power of biological samples. The challenge is to recover correct phase information from experimental diffraction patterns that have a low signal-to-noise ratio and unmeasurable lowest-resolution data. Here, we propose a method to extend spatial resolution by enhancing diffraction signals and by robust phasing. The weak diffraction signals from biological objects are enhanced by interference with strong waves from dispersed colloidal gold particles. The positions of the gold particles determined by Patterson analysis serve as the initial phase, and this dramatically improves reliability and convergence of image reconstruction by iterative phase retrieval. A set of calculations based on current experiments demonstrates that resolution is improved by a factor of two or more.