Crystallization and vitrification of cryoprotectants studied by Raman scattering, Brillouin scattering and THz-TDS

We examine one of the best candidates of cryoprotectant, ethylene glycol aqueous solutions by using Raman and Brillouin scattering and Terahertz time domain spectroscopy. The molecular structure can be determined by Raman scattering and the EG aqueous solutions were investigated to characterize the conformations of molecular structure. The intermediate concentrations of EG solutions easily undergo glass transitions, while the crystallization occurs in the solutions of low and high concentrations of EG. The structural configuration of EG in a crystalline phase in pure EG shows only gauche OCCO form of EG which is the lowest energy conformers, while gauche and trans forms exist in a liquid phase. The dynamical properties from gigahertz to terahertz frequency range are investigated by using Raman scattering, Brillouin scattering and terahertz time domain spectroscopy (THz-TDS). In the present frequency range, the relaxation and vibrational modes coexist. It is shown that the combination of giga to terahertz spectroscopy is a powerful tool to provide information on fast dynamics of bioprotective solutions.