Can xenon in water inhibit ice growth? Molecular dynamics of phase transitions in water–Xe system

Abstract

Motivated by recent experiments showing the promise of noble gases as cryoprotectants, we perform molecular dynamics modeling of phase transitions in water with xenon under cooling. We follow the structure and dynamics of xenon water solution as a function of temperature. Homogeneous nucleation of clathrate hydrate phase is observed and characterized. As the temperature is further reduced we observe hints of dissociation of clathrate due to stronger hydrophobic hydration, pointing towards a possible instability of clathrate at cryogenic temperatures and conversion to an amorphous phase comprised of "xenon + hydration shell" Xe·(H2O)21.5 clusters. Simulations of ice-xenon solution interface in equilibrium and during ice growth reveal the effects of xenon on the ice-liquid interface, where adsorbed xenon causes roughening of ice surface but does not preferentially form clathrate. These results provide evidence against the ice-blocker mechanism of xenon cryoprotection.

Bridging solution properties to gas hydrate nucleation through guest dynamics

“…2) increases, in agreement with previous studies. 22,30,31 With increasing x g , we also see that the location of the solvent-separated peak in Fig. 2 shifts (see the arrow) to slightly smaller separations more consistent with values for a gas hydrate (i.e., 0.62 nm).…”

“…3 shows the dependence of the selfdiffusion coefficients of the guest molecules in solution upon increasing x g at 273.15 K and 250 K. We can see that the selfdiffusion coefficient decreases with increasing x g , which was previously found for xenon solution. 31 This is reasonable given the increasing order in the hydration shell (as noted above). In Fig.…”

Simulations of supercooled water under passive or active stimuli

“…We study in this paper the effect of a hydrophobic molecular motor, the disperse red one DR1 molecule, in supercooled water. Despite the small solubility of hydrophobic molecules in water, hydrophobic molecules dissolved in water have been the subject of a number of experimental and theoretical studies [39][40][41][42][43][44][45][46]. From the experimental point of view the motor can be attached to a hydrophilic molecule to increase its solubility, or be attached to the wall of a pore.…”

Use of Inert Gases for the Preservation of Nuclear Blood Cells

“…Such noble gas as xenon is widely used in practical medicine [8,9]. It has no acute or chronic toxic properties [10][11][12], is not allergenic [13], is highly soluble in lipids [14], has anti-apoptotic effect on cells [15] and forms crystalline hydrates with water [16,17] to reduce its molecular and protein mobility [18][19][20]. Krypton is very similar to xenon in their characteristics, but the biological effects of krypton is poorly studied [21,22].…”