Direct measurement of the critical cooling rate for the vitrification of water

The vitrification of aqueous solutions through rapid cooling is a remarkable achievement that launched the field of cryo-electron microscopy (cryo-EM) and has enabled the cryopreservation of biological specimens. For judging the feasibility of a vitrification experiment, the critical cooling rate of...

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Main Authors: Nathan J. Mowry, Constantin R. Krüger, Marcel Drabbels, Ulrich J. Lorenz
Format: Article
Language:English
Published: American Physical Society 2025-01-01
Series:Physical Review Research
Online Access:http://doi.org/10.1103/PhysRevResearch.7.013095
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author Nathan J. Mowry
Constantin R. Krüger
Marcel Drabbels
Ulrich J. Lorenz
author_facet Nathan J. Mowry
Constantin R. Krüger
Marcel Drabbels
Ulrich J. Lorenz
author_sort Nathan J. Mowry
collection DOAJ
description The vitrification of aqueous solutions through rapid cooling is a remarkable achievement that launched the field of cryo-electron microscopy (cryo-EM) and has enabled the cryopreservation of biological specimens. For judging the feasibility of a vitrification experiment, the critical cooling rate of pure water is a frequently cited reference quantity. However, an accurate determination has remained elusive, with estimates varying by several orders of magnitude. Here, we employ time-resolved electron microscopy to obtain a precise measurement of this quantity. We use shaped microsecond laser pulses to briefly melt an amorphous ice sample before flash freezing it with a variable, well-defined cooling rate. This allows us to directly measure the critical cooling rate of water, which we determine to be 6.4×10^{6}K/s. This result provides important insights into the question of how closely the conformational ensembles in plunge-frozen cryo samples reflect the structure of a protein at room temperature. Moreover, our experimental approach expands the toolkit of microsecond time-resolved cryo-EM, an emerging technique, in which a cryo sample is flash melted and revitrified with a laser pulse in order to enable time-resolved observations of protein dynamics.
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spelling doaj-art-56e4220c15b54bf6a94d32971a3d88712025-01-24T15:04:46ZengAmerican Physical SocietyPhysical Review Research2643-15642025-01-017101309510.1103/PhysRevResearch.7.013095Direct measurement of the critical cooling rate for the vitrification of waterNathan J. MowryConstantin R. KrügerMarcel DrabbelsUlrich J. LorenzThe vitrification of aqueous solutions through rapid cooling is a remarkable achievement that launched the field of cryo-electron microscopy (cryo-EM) and has enabled the cryopreservation of biological specimens. For judging the feasibility of a vitrification experiment, the critical cooling rate of pure water is a frequently cited reference quantity. However, an accurate determination has remained elusive, with estimates varying by several orders of magnitude. Here, we employ time-resolved electron microscopy to obtain a precise measurement of this quantity. We use shaped microsecond laser pulses to briefly melt an amorphous ice sample before flash freezing it with a variable, well-defined cooling rate. This allows us to directly measure the critical cooling rate of water, which we determine to be 6.4×10^{6}K/s. This result provides important insights into the question of how closely the conformational ensembles in plunge-frozen cryo samples reflect the structure of a protein at room temperature. Moreover, our experimental approach expands the toolkit of microsecond time-resolved cryo-EM, an emerging technique, in which a cryo sample is flash melted and revitrified with a laser pulse in order to enable time-resolved observations of protein dynamics.http://doi.org/10.1103/PhysRevResearch.7.013095
spellingShingle Nathan J. Mowry
Constantin R. Krüger
Marcel Drabbels
Ulrich J. Lorenz
Direct measurement of the critical cooling rate for the vitrification of water
Physical Review Research
title Direct measurement of the critical cooling rate for the vitrification of water
title_full Direct measurement of the critical cooling rate for the vitrification of water
title_fullStr Direct measurement of the critical cooling rate for the vitrification of water
title_full_unstemmed Direct measurement of the critical cooling rate for the vitrification of water
title_short Direct measurement of the critical cooling rate for the vitrification of water
title_sort direct measurement of the critical cooling rate for the vitrification of water
url http://doi.org/10.1103/PhysRevResearch.7.013095
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AT marceldrabbels directmeasurementofthecriticalcoolingrateforthevitrificationofwater
AT ulrichjlorenz directmeasurementofthecriticalcoolingrateforthevitrificationofwater