Effect Of Disaccharide On The Devitrification Behavior In Concentrated Glycerol Aqueous Solution

The vitrification preservation method is to solidify the solution into amorphous glass state by rapid cooling on the premise of adding low temperature protectant.This method can effectively avoid the formation of ice crystals in the cooling process,but the antivitrification crystallization is still an important obstacle to the successful vitrification preservation in the rewarming process.Quantitative study on nucleation and growth of ice crystals in the process of reverse vitrification is of great significance for optimizing the vitrification solution and improving the efficiency of cryopreservation.In this paper,the effect of sucrose,trehalose,maltose and lactose on the crystallization of glycerol concentrated solution(60wt%)was studied by means of low temperature microscopy.In order to explain the microcosmic mechanism of this phenomenon,the growth process of ice crystals was simulated by numerical analysis.Based on the phase field theory,the growth models of pure and binary dendrites were established to investigate the effects of anisotropic strength,dimensionless supercooling degree and interfacial free energy on the growth rate and morphology of dendrites.The simulation results show that the tip velocity increases with the increase of supercooling degree.The addition of cryoprotectant changes the equilibrium temperature of the solution,which is beneficial to decrease the supercooling degree and slow down the growth rate of ice crystals.When the strength of anisotropy is large,the dendrite division is obvious,the competition between the main branch and the lateral branch is increased,and the growth rate of the tip is also increased.The addition of disaccharide on the original basis of glycerol solution can increase the viscosity of the solution and reduce the anisotropy.When the interface energy increases,the corresponding growth interface will become smooth,the transverse growth dominance of the dendritic trunk will increase,the axial growth rate will slow down to a certain extent,and the tip will become passivated.The inhibition mechanism of disaccharide on the reverse vitrification process in concentrated solution of propylene glycol was explained in part by numerical simulation results.The results of this paper are of guiding significance for the further understanding of the microscopic growth mechanism of ice crystals and the selection of suitable anti-vitrification inhibitors.