关键词: 细胞脱水, 平衡凝固点, 均相成核温度, 低温保护剂

Abstract: In order to study the homogeneous nucleation temperature of intracellular solution during cooling, an iteration method has been presented to calculate nucleation temperature of system with changeable concentrations. Glycerol was chosen for a cryoprotective agent (CPA) during cooling of mouse oocytes. The equilibriummelting points of intracellular solutions were calculated using an empirical equation determined by the phase diagram of glycerol-sodium chloride-water ternary system. The widely used cell dehydration equation was numerically solved and the concentrations of intracellular solutions as a function of time were calculated. The assumption that the homogeneous nucleation temperature depression was directly proporlianal to the equilibrium melting point depression has been used. The homogeneous nucleation temperatures of intracellular solutions as a function of concentrations were then calculated using the new proposed method coupling with the equilibrium melting points and the concentrations of intracellular solutions. It was found that for glycerol-sodium chloride-water ternary system, depression of the homogeneous nucleation temperature and depression of the equilibrium melting point followed the relation: ⊿Th=1.17⊿Tm . The result proved that the assumption was reasonable and showed that homogeneous nucleation temperatures of aqueous solutions depended on solutes. This research can provide convincing data to support the further study of intracellular ice formation and growth during cooling.

Key words: Cell dehydration, Equilibriummelting point, Homogeneous nucleation temperature, Cryoprotective agent