Research on Ice Crystal Growth Inside the Vitrified Vs55 with Magnetic Nanoparticles During Devitrification by Cryomicroscopy

Abstract

The effect of magnetic nanoparticles(mNPs) on the devitrification crystallization of typical vitrification solution Vs55 was systematically explored by differential scanning calorimetry(DSC) and cryomicroscope system. The results show that, (i) the mNPs coated by both carboxylic acid(CA) and polyethylene glycol(PEG) had little effect on the glass transition temperature(Tg) of Vs55, but had significant effect on the devitrification transition temperature(Td) and devitrification enthalpy $({H_{{T_{\rm{d}}}}})$ , (ii) in the range of the devitrification area(−85— −60 °C), the MNPs coated by CA can significantly accelerate the devitrification of Vs55 as the isothermal temperatures and the cooling rates increased, and the ice growth rate was 0.37 μm/s at the isothermal temperature of −85 °C, and was about 2.19 μm/s at −75 °C. Also, the ice growth rates rose from 1.72 μm/s to 3.54 μm/s when the cooling rates were increased from 2 °C/min to 100 °C/min(at the isothermal temperature of −75 °C), (iii) magnetic nanoparticles coated by both PEG and CA could promote the devitrification of Vs55, for instance, without any crystal growth inside Vs55 at the isothermal temperature of −80 °C, but 1.04 and 2.31 μm/s for adding magnetic nanoparticles coated by CA and PEG, respectively. Compared with the samples coated by CA, PEG promoted the devitrification of Vs55 in a much more positive way, and the ice growth rates were 0.62 and 6.25 μm/s at the isothermal temperatures of −85 and −75 °C, respectively. These results indicate that the surface coating of MNPs could significantly affect the recrystallization of Vs55, and further work should be conducted in the future research.