Sample Preparation Optimization for Laboratory Soft X-Ray Microscopy

Abstract: With the introduction of nanoparticles in health care and daily products, the interaction between cells and nanoparticles is of great interest. There are many ways to examine these interactions, one of them being soft X-ray microscopy. It is a technique utilizing the water window to image biological samples, its greatest benefit being the non-invasive sample preparation, keeping the cell in a near-native state. The Stockholm Laboratory Soft X-ray Microscopy is a compact soft X-ray microscope that is currently being used to examine cell interactions. However, the sample preparations have been inconsistent and have yielded few useful and reproducible results. The purpose of this project is to optimize the cell preparation for better imaging using the Stockholm Laboratory Soft X-ray Microscope.  To reach the project goal to enable imaging of the nucleus and organelles in macrophages, this thesis will present a sample preparation protocol for macrophages where the concentration, blotting and cryo-fixation of the samples have been improved. The macrophage preparation was also tried on two other types of cells, amoeba and HEK 293 cells, to see if this preparation is universal for all cell lines. The results indicated that the most difficult and crucial step is the blotting, as too dry samples destroy the cells and too wet samples will yield almost no transmission in the microscope, making it impossible to image.