Limits...
Strong isotope effects on melting dynamics and ice crystallisation processes in cryo vitrification solutions.

Kirichek O, Soper A, Dzyuba B, Callear S, Fuller B - PLoS ONE (2015)

Bottom Line: We also observe strong water isotope effects on ice crystallisation processes in the cryoprotectant mixture.This behaviour might be explained by nuclear quantum effects in water.The strong isotope effect, observed here, may play an important role in development of new cryopreservation strategies.

View Article: PubMed Central - PubMed

Affiliation: ISIS facility, STFC, Rutherford Appleton Laboratory, Harwell Oxford Campus, Didcot, Oxon, United Kingdom.

ABSTRACT
The nucleation and growth of crystalline ice during cooling, and further crystallization processes during re-warming are considered to be key processes determining the success of low temperature storage of biological objects, as used in medical, agricultural and nature conservation applications. To avoid these problems a method, termed vitrification, is being developed to inhibit ice formation by use of high concentration of cryoprotectants and ultra-rapid cooling, but this is only successful across a limited number of biological objects and in small volume applications. This study explores physical processes of ice crystal formation in a model cryoprotective solution used previously in trials on vitrification of complex biological systems, to improve our understanding of the process and identify limiting biophysical factors. Here we present results of neutron scattering experiments which show that even if ice crystal formation has been suppressed during quench cooling, the water molecules, mobilised during warming, can crystallise as detectable ice. The crystallisation happens right after melting of the glass phase formed during quench cooling, whilst the sample is still transiting deep cryogenic temperatures. We also observe strong water isotope effects on ice crystallisation processes in the cryoprotectant mixture. In the neutron scattering experiment with a fully protiated water component, we observe ready crystallisation occurring just after the glass melting transition. On the contrary with a fully deuteriated water component, the process of crystallisation is either completely or substantially supressed. This behaviour might be explained by nuclear quantum effects in water. The strong isotope effect, observed here, may play an important role in development of new cryopreservation strategies.

No MeSH data available.


Related in: MedlinePlus

Differential cross sections for fully protiated sample.Cooling after heating scan.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4376522&req=5

pone.0120611.g005: Differential cross sections for fully protiated sample.Cooling after heating scan.

Mentions: The situation changed dramatically in case of the fully protiated sample (40% H2O; 23% PD (h); 17% Met (h); 20% DMSO (h)). As we can see in Fig. 4 the sample was again in the glassy state at temperatures below 150 K. However at 160 K, immediately above glass melting transition, the strong diffraction peaks from water crystallites appear in the data. Once they have appeared these peaks remain in the diffraction data during heating up to the maximum temperature 220 K, as well as during consequent second cooling run back to 82 K (see Fig. 5). The diffraction signal does not change even around the glass solidification transition at 150 K. (Note that due to the change in scattering length from +6.67fm for the deuteron compared to −3.74fm for the proton the Bragg peaks in the protiated sample occur at quite different Q values compared to the deuteriated sample. The different position of these peaks is a direct indication of ice Ih formation.).


Strong isotope effects on melting dynamics and ice crystallisation processes in cryo vitrification solutions.

Kirichek O, Soper A, Dzyuba B, Callear S, Fuller B - PLoS ONE (2015)

Differential cross sections for fully protiated sample.Cooling after heating scan.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4376522&req=5

pone.0120611.g005: Differential cross sections for fully protiated sample.Cooling after heating scan.
Mentions: The situation changed dramatically in case of the fully protiated sample (40% H2O; 23% PD (h); 17% Met (h); 20% DMSO (h)). As we can see in Fig. 4 the sample was again in the glassy state at temperatures below 150 K. However at 160 K, immediately above glass melting transition, the strong diffraction peaks from water crystallites appear in the data. Once they have appeared these peaks remain in the diffraction data during heating up to the maximum temperature 220 K, as well as during consequent second cooling run back to 82 K (see Fig. 5). The diffraction signal does not change even around the glass solidification transition at 150 K. (Note that due to the change in scattering length from +6.67fm for the deuteron compared to −3.74fm for the proton the Bragg peaks in the protiated sample occur at quite different Q values compared to the deuteriated sample. The different position of these peaks is a direct indication of ice Ih formation.).

Bottom Line: We also observe strong water isotope effects on ice crystallisation processes in the cryoprotectant mixture.This behaviour might be explained by nuclear quantum effects in water.The strong isotope effect, observed here, may play an important role in development of new cryopreservation strategies.

View Article: PubMed Central - PubMed

Affiliation: ISIS facility, STFC, Rutherford Appleton Laboratory, Harwell Oxford Campus, Didcot, Oxon, United Kingdom.

ABSTRACT
The nucleation and growth of crystalline ice during cooling, and further crystallization processes during re-warming are considered to be key processes determining the success of low temperature storage of biological objects, as used in medical, agricultural and nature conservation applications. To avoid these problems a method, termed vitrification, is being developed to inhibit ice formation by use of high concentration of cryoprotectants and ultra-rapid cooling, but this is only successful across a limited number of biological objects and in small volume applications. This study explores physical processes of ice crystal formation in a model cryoprotective solution used previously in trials on vitrification of complex biological systems, to improve our understanding of the process and identify limiting biophysical factors. Here we present results of neutron scattering experiments which show that even if ice crystal formation has been suppressed during quench cooling, the water molecules, mobilised during warming, can crystallise as detectable ice. The crystallisation happens right after melting of the glass phase formed during quench cooling, whilst the sample is still transiting deep cryogenic temperatures. We also observe strong water isotope effects on ice crystallisation processes in the cryoprotectant mixture. In the neutron scattering experiment with a fully protiated water component, we observe ready crystallisation occurring just after the glass melting transition. On the contrary with a fully deuteriated water component, the process of crystallisation is either completely or substantially supressed. This behaviour might be explained by nuclear quantum effects in water. The strong isotope effect, observed here, may play an important role in development of new cryopreservation strategies.

No MeSH data available.


Related in: MedlinePlus