EMC acquired the HPF Compact 02 by Martin Wohlwend in April 2016. Its robust, reliable and tested design offers excellent cryofixation quality with great reproducibility.
- Maximum operating pressure: 2970 bar (43,068 psi)
- Cooling time 0 °C to -100 °C: <10 ms
- Freezing cycles possible per hour: 40
- Patented Valve starts freezing process only after pressure of 2050 bar is reached
- Electrically heated components, including specimen chamber controlled +/- 1°C
- Incorporated Oscilloscope with USB interface to external PC
- Largest variety of specimen carriers, 3 mm, 6 mm, copper tubes, omega style carriers, cellulose capillary tubes, sapphire disks
- Correlative light microscopy accessory
- Copper tube freezing system
Chemical fixation vs. high pressure freezing
Chemical fixation followed by dehydration and embedding in resin has been widely used as standard processing method for biological specimen. However, there are major drawbacks using this method. First, the chemical agents influence and change the sample on the cellular and molecular levels during the fixation process. Second, the fixation process is relatively slow and thus not suitable to visualize rapidly occurring events.
The disadvantages of the slow chemical fixation process can be overcome by using cryofixation methods. Cryofixation (or rather cryo-immobilization) means the very rapid freezing of biological samples which leads to the arrest of physiological events within milliseconds. This is favorable for the examination of dynamic processes like vesicle trafficking or virus envelopment.
Adequate freezing of biological samples at ambient pressure can only be achieved up to a thickness of 10 µm due to formation of water ice crystals which distort the ultrastructure. High pressure (2100 bar) facilitates good freezing of up to 0.3 mm thick samples by significantly reducing the rate of ice crystal formation.
What types of samples can be processed using HPF?
A wide variety of biological samples can be used including cell monolayers, tissue up to 0.3 mm, cell suspensions, and whole small animals (e.g. nematodes) or embryos (e.g. fruit flies).
What are the advantages of HPF?
Specimens are frozen within milliseconds, immediately immobilizing highly dynamic processes and eliminating artefacts commonly seen after traditional TEM processing such as disruption of ultrastructure due to osmotic stress or temperature changes.
If you are interested in high pressure freezing of your samples please contact Martin Schauflinger. You can find more information here:
- McDonald, K.L. (2014). Out with the old and in with the new: rapid specimen preparation procedures for electron microscopy of sectioned biological material. Protoplasma 251, 429–448.
Austin, J.R. (2014). High-Pressure Freezing and Freeze Substitution of Arabidopsis for Electron Microscopy. In Arabidopsis Protocols, J.J. Sanchez-Serrano, and J. Salinas, eds. (Totowa, NJ: Humana Press), pp. 473–486.
McDonald, K. (2007). Cryopreparation Methods for Electron Microscopy of Selected Model Systems. In Methods in Cell Biology, (Elsevier), pp. 23–56.