Microstructural free volume and dynamics of cryoprotective DMSO–water mixtures at low DMSO concentration

Abstract

Positron annihilation lifetime spectroscopy reveals changes in the DMSO–water microstructure in low concentrations of DMSO (1.8%, 2.0% and 10% v/v) that have a great impact on the cryoprotective effect during the cryopreservation of cells.

On crystallization of water confined in liposomes and cryoprotective action of DMSO

“…In the past, it was shown that in a two-component water–DMSO mixture (without lipid bilayer), slow heating during the thawing led to a decrease of the o -Ps lifetime in the critical temperature range of 165 K to 200 K, as long as quick heating suppressed the drop-down of o -Ps lifetime, what was interpreted as avoiding the crystallization. 18 There is a work, 53 where a positive correlation was found between the cell post-thaw viability and the heating rate through the temperature range of 180 K to 200 K during thawing, what matches critical temperature range for crystallization of water–DMSO eutectic mixture observed in our experiments. It is known that during slow (equilibrium) cooling, biological cells are directly surrounded by the freeze-concentrated phase of cryoprotective agents and other dissolved substances in cryopreservation cell medium (inorganic salts, etc.…”

“…[15][16][17] DMSO can form an amorphous fraction in the freezing mixture with water, which allows intracellular vitrication. 18,19 It was shown that this amorphous fraction consisting of freeze-concentrated DMSO is metastable and can crystallize during slow thawing, threatening cell viability. 18 In this work, the solidication and melting processes of water-DMSO mixtures containing liposomes were studied.…”

“…18,19 It was shown that this amorphous fraction consisting of freeze-concentrated DMSO is metastable and can crystallize during slow thawing, threatening cell viability. 18 In this work, the solidication and melting processes of water-DMSO mixtures containing liposomes were studied. Liposomes are supramolecular aggregates of lipid molecules aligned into a lipid bilayer.…”

“…Combination of these experimental techniques has been proven to be suitable for studying the phase behavior of various substances and mixtures. 18,21,22 PALS is an experimental method of nuclear physics using the triplet bound state of positron and electronortho-positronium (o-Ps)as a probe for detecting microstructural changes in the studied materials during variations of external parameters such as temperature, pressure or time. The advantage of the PALS method is high sensitivity of the o-Ps lifetime to changes in microstructure related to phase transitions or other structural rearrangements.…”

“… 18,19 It was shown that this amorphous fraction consisting of freeze-concentrated DMSO is metastable and can crystallize during slow thawing, threatening cell viability. 18 …”