| 1. |
|
|
| 2. |
- Dehlinger, Aurelie, et al.
(författare)
-
Laboratory Soft X-Ray Microscopy with an Integrated Visible-Light Microscope-Correlative Workflow for Faster 3D Cell Imaging
- 2020
-
Ingår i: Microscopy and Microanalysis. - : Cambridge University Press (CUP). - 1431-9276 .- 1435-8115. ; 26:6, s. 1124-1132
-
Tidskriftsartikel (refereegranskat)abstract
- Laboratory transmission soft X-ray microscopy (L-TXM) has emerged as a complementary tool to synchrotron-based TXM and high-resolution biomedical 3D imaging in general in recent years. However, two major operational challenges in L-TXM still need to be addressed: a small field of view and a potentially misaligned rotation stage. As it is not possible to alter the magnification during operation, the field of view in L-TXM is usually limited to a few tens of micrometers. This complicates locating areas and objects of interest in the sample. Additionally, if the rotation axis of the sample stage cannot be adjusted prior to the experiments, an efficient workflow for tomographic imaging cannot be established, as refocusing and sample repositioning will become necessary after each recorded projection. Both these limitations have been overcome with the integration of a visible-light microscope (VLM) into the L-TXM system. Here, we describe the calibration procedure of the goniometer sample stage and the integrated VLM and present the resulting 3D imaging of a test sample. In addition, utilizing this newly integrated VLM, the extracellular matrix of cryofixed THP-1 cells (human acute monocytic leukemia cells) was visualized by L-TXM for the first time in the context of an ongoing biomedical research project.
|
|
| 3. |
|
|
| 4. |
- Fogelqvist, Emelie, et al.
(författare)
-
Laboratory cryo x-ray microscopy for 3D cell imaging
- 2017
-
Ingår i: Scientific Reports. - : NATURE PUBLISHING GROUP. - 2045-2322. ; 7
-
Tidskriftsartikel (refereegranskat)abstract
- Water-window x-ray microscopy allows two-and three-dimensional (2D and 3D) imaging of intact unstained cells in their cryofixed near-native state with unique contrast and high resolution. Present operational biological water-window microscopes are based at synchrotron facilities, which limits their accessibility and integration with complementary methods. Laboratory-source microscopes have had difficulty addressing relevant biological tasks with proper resolution and contrast due to long exposure times and limited up-time. Here we report on laboratory cryo x-ray microscopy with the exposure time, contrast, and reliability to allow for routine high-spatial resolution 3D imaging of intact cells and cell-cell interactions. Stabilization of the laser-plasma source combined with new optics and sample preparation provide high-resolution cell imaging, both in 2D with ten-second exposures and in 3D with twenty-minute tomography. Examples include monitoring of the distribution of carbon-dense vesicles in starving HEK293T cells and imaging the interaction between natural killer cells and target cells.
|
|
| 5. |
- Fogelqvist, Emelie, et al.
(författare)
-
Stability of liquid-nitrogen-jet laser-plasma targets
- 2015
-
Ingår i: Journal of Applied Physics. - : American Institute of Physics (AIP). - 0021-8979 .- 1089-7550. ; 118:17
-
Tidskriftsartikel (refereegranskat)abstract
- Microscopic jets of cryogenic substances such as liquid nitrogen are important regenerative high-density targets for high-repetition rate, high-brightness laser-plasma soft x-ray sources. When operated in vacuum such liquid jets exhibit several non-classical instabilities that negatively influence the x-ray source's spatial and temporal stability, yield, and brightness, parameters that all are important for applications such as water-window microscopy. In the present paper, we investigate liquid-nitrogen jets with a flash-illumination imaging system that allows for a quantitative stability analysis with high spatial and temporal resolution. Direct and indirect consequences of evaporation are identified as the key reasons for the observed instabilities. Operating the jets in an approximately 100 mbar ambient atmosphere counteracts the effects of evaporation and produces highly stable liquid nitrogen jets. For operation in vacuum, which is necessary for the laser plasmas, we improve the stability by introducing an external radiative heating element. The method significantly extends the distance from the nozzle that can be used for liquid-jet laser plasmas, which is of importance for high-average-power applications. Finally, we show that laser-plasma operation with the heating-element-stabilized jet shows improved short-term and long-term temporal stability in its water-window x-ray emission.
|
|
| 6. |
- Kördel, Mikael, et al.
(författare)
-
Biological Laboratory X-Ray Microscopy
- 2019
-
Ingår i: X-Ray Nanoimaging. - : SPIE - International Society for Optical Engineering. - 9781510629189
-
Konferensbidrag (refereegranskat)abstract
- Zone-plate-based soft x-ray microscopes operating in the water window allow high-resolution and high-contrast imaging of intact cells in their near-native state. Laboratory-source-based x-ray microscopes are an important complement to the accelerator-based instruments, providing high accessibility and allowing close integration with other cell-biological techniques. Here we present recent biological applications using the Stockholm laboratory water-window x-ray microscope, which is based on a liquid-nitrogen-jet laser-plasma source. Technical improvements to the microscope in the last few years have resulted in increased x-ray flux at the sample and significantly improved stability and reliability. In addition to this, vibrations in key components have been measured, analyzed and reduced to improve the resolution to 25 nm half-period. The biological applications include monitoring the development of carbon-dense vesicles in starving human embryonic kidney cells (HEK293T), imaging the interaction between natural killer (NK) cells and HEK293T target cells, and most recently studying a newly discovered giant DNA virus and the process of viral replication inside a host amoeba. All biological imaging was done on cryo-frozen hydrated samples in 2D and in some cases 3D.
|
|
| 7. |
- Kördel, Mikael
(författare)
-
Biological Laboratory X-Ray Microscopy
- 2020
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Soft x-ray microscopy in the water window (? ≈ 2.3 − 4.3 nm) is a powerful technique for high-resolution biological imaging. The strong natural contrast between carbon-based structures and water allows visualization of hydrated and unstained samples, while providing enough transmission through up to ∼ 10 μm of organic matter. Furthermore, the full potential of this technique can be exploited by performing computed tomography, thus obtaining a complete 3D image of the object.Routine short-exposure water-window microscopy of whole cells and tissue is currently performed at synchrotron-radiation facilities around the world, but with a limited accessibility to the wider research community. For this reason, laboratory-based systems have been developed, which are now reaching maturity. The benefits compared to the synchrotron-based instruments include easier integration with complementary methods in the home laboratory, in addition to the increased access that allows for the often time-consuming optimization of experimental parameters as well as longitudinal studies.This Thesis presents recent developments of the Stockholm laboratory x-ray microscope as well as several biological applications. Work has been done on improving the mechanical and thermal stability of the microscope, resulting in a resolution of 25 nm (half period) in images of test targets. The biological applications were enabled by a significantly increased x-ray flux through the system as well as an improved operational stability. This work demonstrates 10-second exposure imaging of whole cryofixed cells, imaging of viral infections in cells, and 20 minutes total exposure cryotomography.
|
|
| 8. |
- Kördel, Mikael, et al.
(författare)
-
Biological Laboratory X-ray Microscopy
- 2018
-
Ingår i: Microscopy and Microanalysis. - 1431-9276 .- 1435-8115. ; 24:S2, s. 346-347
-
Tidskriftsartikel (refereegranskat)
|
|
| 9. |
|
|
| 10. |
- Kördel, Mikael, et al.
(författare)
-
Laboratory water-window x-ray microscopy
- 2020
-
Ingår i: Optica. - : The Optical Society. - 2334-2536. ; 7:6, s. 658-674
-
Forskningsöversikt (refereegranskat)abstract
- Soft x-ray microscopy in the water window (similar to 285-535 eV) is an emerging and unique tool for 2D and 3D imaging of unstained intact cellular samples in their near-native state with few-10-nm detail. However, present microscopes rely on the high x-ray brightness of synchrotron-radiation sources. Having access to water-window microscopy in the home laboratory would increase the impact and extend the applicability of the method. In the present paper, we review three decades of efforts to build laboratory water-window microscopes and conclude that the method is now reaching the maturity to allow biological studies. The instruments as well as their key components are quantitatively and qualitatively compared. We find that the brightness and the reliability of the laboratory source are the most critical parameters, but that the optics as well as the sample preparation also must be optimized to enable high-resolution imaging with adequate exposure times. We then describe the two sister microscopes in Stockholm and Berlin, which allow reliable high-resolution biological imaging with short exposure times of a few tens of seconds in 2D and a few tens of minutes in 3D. They both rely on a liquid-jet laser-plasma source combined with high-reflectivity normal-incidence multilayer condenser optics, high-resolution zone-plate imaging optics, CCD detection, and cryogenic sample handling. Finally, we present several examples of biological imaging demonstrating the unique properties of these instruments.
|
|
