Predict the glass transition temperature of glycerol–water binary cryoprotectant by molecular dynamic simulation

• Published in: Cryobiology 2008-04, Vol.56 (2), p.114-119
• Main Authors: Li, Dai-Xi, Liu, Bao-Lin, Liu, Yi-shu, Chen, Cheng-lung
• Format: Article
• Language: English
• Subjects: Calorimetry, Differential Scanning; Chemical Phenomena; Chemistry, Physical; Computer Simulation; Cryoprotectant; Cryoprotective Agents - chemistry; Glass transition temperature; Glycerol - chemistry; Models, Molecular; Molecular dynamics simulation; Phase Transition; Solutions - chemistry; Temperature; Thermodynamics; Vitrification; Water - chemistry
• ISSN: 0011-2240; 1090-2392
• DOI: 10.1016/j.cryobiol.2007.11.003

Vitrification is proposed to be the best way for the cryopreservation of organs. The glass transition temperature ( T g) of vitrification solutions is a critical parameter of fundamental importance for cryopreservation by vitrification. The instruments that can detect the thermodynamic, mechanical and dielectric changes of a substance may be used to determine the glass transition temperature. T g is usually measured by using differential scanning calorimetry (DSC). In this study, the T g of the glycerol-aqueous solution (60%, wt/%) was determined by isothermal-isobaric molecular dynamic simulation (NPT-MD). The software package Discover in Material Studio with the Polymer Consortium Force Field (PCFF) was used for the simulation. The state parameters of heat capacity at constant pressure ( C p), density ( ρ), amorphous cell volume ( V cell) and specific volume ( V specific) and radial distribution function (rdf) were obtained by NPT-MD in the temperature range of 90–270 K. These parameters showed a discontinuity at a specific temperature in the plot of state parameter versus temperature. The temperature at the discontinuity is taken as the simulated T g value for glycerol–water binary solution. The T g values determined by simulation method were compared with the values in the literatures. The simulation values of T g (160.06–167.51 K) agree well with the DSC results (163.60–167.10 K) and the DMA results (159.00 K). We drew the conclusion that molecular dynamic simulation (MDS) is a potential method for investigating the glass transition temperature ( T g) of glycerol–water binary cryoprotectants and may be used for other vitrification solutions.