AJP - Regulatory, Integrative and Comparative Physiology, Vol 267, Issue 6 1646-R1652, Copyright © 1994 by American Physiological Society
Temperature gradient osmometer and anomalies in freezing temperatures
A. Arav and B. Rubinsky
Department of Mechanical Engineering, University of California, Berkeley 94720.
We have developed a new device that measures freezing and melting
temperatures in nanoliter volume samples and can be used as a "freezing
point osmometer" with a resolution many orders of magnitude greater than
that of existing freezing point osmometers. Using this device we found
anomalies in the depression of the freezing temperature and thermal
hysteresis in aqueous solutions of hydrophilic amino acids, polyamino
acids, and lectins. These anomalies would not have been possible to detect
with currently used technology. The compounds that produce anomalies in
freezing temperature were reported in the literature as having the ability
to bind to cell membranes. This suggests a relation between a molecule's
ability to bind to cell membranes and its anomalous freezing temperature
depression. The new freezing point osmometer and our results could be
important for studying and understanding organic molecules and their
interaction with membranes and water.
