Laboratory Soft X-Ray Microscopy for Biological Imaging
Time: Fri 2025-01-17 10.00
Location: Kollegiesalen, Brinellvägen 8, Stockholm
Language: English
Subject area: Biological Physics
Doctoral student: Komang Arsana , Bio-Opto-Nanofysik, Biomedical and X-rays Physics
Opponent: Professor Juergen Thieme, Institute for X-Ray Physics, Georg-August University Goettingen
Supervisor: Hans Hertz, Fysik, Bio-Opto-Nanofysik; Ulrich Vogt, Bio-Opto-Nanofysik; Jonas A. Sellberg, Bio-Opto-Nanofysik
QC 2025-01-03
Abstract
Soft x-ray microscopy within the water window is a powerful technique for high-resolution biological imaging due to its capability to image whole, intact cells (approximately 10 μm thick) in their near-native cellular environment. The short wavelength of water-window radiation (λ = 2.3 − 4.4 nm, E = 284−540 eV) used in this imaging technique provides high natural contrast for cellular imaging due to the significant difference in soft x-ray attenuation lengths between organic materials, such as proteins and lipids (i.e., carbon), and water (i.e., oxygen). In addition to the high imaging contrast, the high penetration of soft x-rays eliminates the need for laborious sample preparation, including sectioning, chemical fixation, heavy-metal staining, and fluorescence labeling. The majority of soft x-ray microscopes are operated using synchrotron radiation sources, as they require x-ray sources with high spectral brightness, which limits accessibility. To complement these synchrotron-based instruments, we develop a laboratory-based soft x-ray microscope as alternative system for biological imaging. Motivated by this background, this thesis presents the development of laboratory soft x-ray microscopy focused on improving image resolution and optimizing sample preparation. The resolution has been improved to 25 nm(half-period) through vibration analysis and mitigation. Sample preparation optimization was achieved by controlling the ice thickness during devitrification process, applied to both manual plunge-freezing and automated systems, allowing for the preservation of cellular structures and improved image quality. These developments have enabled the establishment of methodology for investigating nanoparticle interactions in-vitro and in-vivo, relying solely on x-ray imaging. These advancements have enabled the investigation of uptake and dynamics of nanoparticles in organelles. Moreover, the applications extend beyond bio-nano interactions; they have also facilitated quantitative studies in viral infections of giant DNA viruses.