Effects of nanoparticles on devitrification and recrystallization of aqueous glycerol and PEG-600 solutions

Abstract

Nanoparticles in solution offer unique electrical, mechanical and thermal properties due to their physical presence and interaction with the state of dispersion. This work is aimed to study the effects of hydroxyapatite (HA) nanoparticles on the behavior of devitrification and recrystallization of glycerol (60% w/w) and PEG-600 (50% w/w) solutions during warming. HA nanoparticles of different sizes (20, 40, 60 nm) and concentrations (0.1%, 0.5%, w/w) were incorporated into solutions, and were studied by calorimetric analysis coupled with cryomicroscopy. The presence of HA nanoparticles has little effect on the devitrification end temperatures, but affects the devitrification onset temperatures of glycerol and PEG-600 solutions. The investigation with the cryomicroscope observed that the ice morphologies of glycerol and PEG-600 solutions are dendritic and spheric respectively. The ice fraction of glycerol solution containing 0.1% HA with the size of 60 nm decreased to 2/5 of that of the solution without nanoparticles at −45°C. The ice fractions of PEG-600 solutions increased significantly between −64°C and −54°C, and the ice fraction of PEG-600 solution without nanoparticles increased by 92% within the temperature range. The findings have significant implications for biomaterial cryopreservation, cryosurgery, and food manufacturing. The complexity of ice crystal growth kinetics in nanoparticle-containing solutions awaits further study.