Development of High Resolution X-ray Microscopy

高分辨率X射线显微镜的研制一台扫描软X射线显微镜已经在布鲁克海文国家实验室的国家同步辐射光源上建成并投入使用。该仪器利用XLA光束线上明亮的、可调谐的波动光源。它使用波带片形成55 nm的束斑，非常适合研究湿的、未染色的样品。将进一步开发新的成像模式，使用元素吸收边(XANE)附近的共振来绘制特定的化学状态，并使用对发光标签中激发的可见光的检测进行免疫标记。该仪器将进行改装，以接受冰冻的水合标本。这将最大限度地减少放射性蚀刻对标本的损害；为了在潮湿的生物标本中达到更高的分辨率，以及在需要水合标本的多个图像的研究中，例如在断层扫描和化学测绘中，这一步骤是必要的。虽然电子显微镜可以高分辨率地观察薄的冰冻切片，但我们的仪器将更适合于检查厚(1-10米水层)的整个样品，而不需要切片。仪器分辨率将提高到20-30 nm的水平，使用更高的分辨率波带片。随着光源亮度的计划升级，在拟议的赠款期间，显微镜仍将是同类仪器中的首选仪器。这些仪器的开发将有助于涉及以下系统的研究：染色体和染色体折叠、疟疾红细胞、精子中蛋白质和DNA的分布，以及海胆胚胎分化中的脊椎形成。这些合作的生物学研究将继续并扩大，特别是通过增加一名具有生物学而不是X射线物理背景的博士后。该团队还欢迎对使用该仪器解决与其独特能力匹配的其他生物问题感兴趣的研究人员的询问。

Development of High Resolution X-ray Microscopy A scanning soft x-ray microscope has been built and put into operation at the National Synchrotron Light Source at Brookhaven National Laboratory. The instrument makes use of the bright, tuneable undulator source at the XlA beamline. It uses zone plates to form a 55 nm beam spot, and is well suited to the study of wet, unstained specimens. New imaging modes will be developed further to map particular chemical states using the resonances present near elemental absorption edges (XANES), and to use the detection of visible light excited in luminescent tags for immunolabelling. The instrument will be modified to accept frozen hydrated specimens. This will minimize specimen damage due to radiolytical etching; such a step is necessary to reach higher resolution in wet biological specimens, and for studies where multiple images of hydrated specimens are required, such as in tomography and chemical mapping. Whereas electron microscopes can view thin cryosections at high resolution, our instrument will be better suited to examining thick (1-10 ,m water layer) whole specimens, without the need for sectioning. The instrumental resolution will be improved to the 20-30 nm level using higher resolution zone plates. With the planned brightness upgrade of the Light Source, the microscope will remain the premier instrument of its type through the proposed grant period. These instrumentation developments will be undertaken to aid research involving the following systems: chromosomes and chromosome folding, malarial erythrocytes, the distribution of protein and DNA in sperms, and spine formation in sea urchin embryo differentiation. These collaborative biological investigations will be continued and expanded, especially by the addition of a postdoc with biological rather than x-ray physics background. The team also welcomes inquiries by investigators interested in using the instrument to solve additional biological problems mat ched to its unique capabilities.