Abstract
Interactions among water, ice, and solute in frozen organic solutions play an important role in stability during cryopreservation. The aim of this study was therefore to investigate microscopic distribution of water, ice, and organic matters after freezing at different conditions. Trehalose and albumin solutions filled in a microchannel were placed on a directional solidification stage combined with a laser raman microscope. The directional solidification stage maintained one end of the channel at -20℃ and the other end at +20℃ so that the solution could be solidified from one end to the other. The spectra of C-H and O-H bonds were respectively obtained by scanning the frozen solution with the laser raman microscope. organic matters or CH-rich regions were finely dispersed at highly supercooled areas because of the higher solidification speed. They however condensed as visible spots at lower supercooled areas since the solutes were rejected during freezing and entrapped between ices. Near the ice front, the organic matters were almost completely rejected from the ice. The results demonstrated that raman imaging is a powerful tool to visualize the distribution of organic matters depending on the degree of supercooling and thus the solidification speed.
