X-Ray Micro- and Nano-Diffraction Imaging on Human Mesenchymal Stem Cells and Differentiated Cells

by Marten Bernhardt
Doctoral thesis
Date of Examination:2016-06-15
Date of issue:2017-06-13
Advisor:Prof. Dr. Tim Salditt
Referee:Dr. Florian Rehfeldt
Referee:Prof. Dr. Andreas Janshoff
Persistent Address: http://dx.doi.org/10.53846/goediss-6343

 

 

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Abstract

English

Recent advances in hard x-ray optics, instrumentation and detection have made it possible to probe biological samples by combining diffraction with raster scanning, using step sizes on the order of cellular organelle dimensions and below. The data obtained from such experiments encode the local electron density in a 2D-diffraction pattern for each scan position and provide information down to molecular scales. In this way, scanning transmission x-ray microscopy (with full diffraction data) complements very well the repertoire of high resolution imaging techniques. However, the challenge is to decode the wealth of structural information in each pattern of the scan array: This work presents results on different adherent eukaryotic cells with special focus on the methodology of sample handling and automated data analysis, in particular aiming at the filamentous actin network of single cells. The algorithms proposed are applied to cellular diffraction data of cells in different states - ranging from freeze-dried to the more challenging alive preparations - and analyze the signals in a model-free and robust manner. Provided with sufficient statistics, the analysis procedures and derived observables introduced here may be well-suited to characterize biological cells and tissues in future x-ray raster scanning experiments.
Keywords: scanning SAXS; actin; biological cells; principal component analysis; hMSCs; cardiac tissue cells; automated data analysis; structural observables; comparative analysis; micro-SAXS; nano-SAXS
 
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