Biological soft x-ray contact microscopy: Imaging living CHO-SC1 cells and other biological materials.

摘要

This dissertation is a description of soft x-ray contact microscopy and the successful efforts to expand this technique to image at high resolution, living mammalian cells. Soft x-ray contact microscopy (SXCM) is a form of x-ray lithography, however, the biological cell is imaged instead of an electron-cut microcircuit mask. The contrast mechanism is based upon the x-ray absorption lengths of carbon and nitrogen. The soft x-rays were generated by a conventional laboratory source or a laser-induced plasma x-ray source. The conventional laboratory soft x-ray source, was a converted electron evaporator. The target materials were vanadium, and carbon. The laser-induced plasma x-ray source was the Lawrence Livermore National Laboratory (LLNL) JANUS laser facility. The target material was tantalum. A radiachromic nylon film was used to calibrate the exposure dose. The imaging detector was an x-ray sensitive resist or a copolymer. A wet cell chamber (WCC) was designed to keep a biological sample alive at atmospheric pressure yet permit imaging by soft x-rays. The limits of resolution required an understanding of the interaction of soft x-rays with matter, Fresnel diffraction, penumbral blurring and secondary electron travel within a resist. The imaging of the biological samples included sample preparation, resist development and electron microscope readout of the resist. The biological samples were fixed erythrocytes and zymogen granules, and critical point dried 9L glialsarcoma cells. The major result of this work was the first pictures of living mammalian cells, CHO-SC1, by SXCM. The LLNL JANUS laser facility was the x-ray source for the living cell x-ray micrographs. 155 refs., 69 figs.