Multiple Unfrozen Water Fractions in Biological Tissues: Freezing Point and Size
Cameron IL1*, Haskin CL2 and Fullerton GD3
1Department of Cellular and Structural Biology, University of Texas Health Science at San Antonio, San Antonio, Texas 78229-3900
2School of Dental Medicine, University of Nevada Las Vegas, Las Vegas, Nevada 89106
3Department of Radiology, University of Colorado, 12700 E. 19th Ave. Aurora, Colorado 80045-2507
*Correspondence E-mail: cameron@uthscsa.edu
Key Words: Water, Freezing, Tissues, Collagen
Received July 18th, 2012; Accepted May 13th, 2013; Published May 30th, 2013; Available online June 5th, 2013
Abbreviations Guide: SHM: stoichiometric hydration model, g/g: grams water per g dry mass, s: seconds, OUR: osmotically unresponsive, NMR: nuclear magnetic resonance, ESR: electron spin resonance, DSC: differential scanning colorimetry, TMJ: temporalmandibular disk, SEM: standard error of mean, ˚C: degrees centigrade.
Abstract
This minireview deals with multiple freezing temperatures and sizes (in gwater/g dry mass) of individual unfrozen water fractions in biological specimens.Data were compiled from animal, plant and microcrystalline cellulose reports. Multiple freezing points (FP) were reported in all eight of the samples surveyed. The freezing points of water fractions occurred most frequently at temperature intervals of -6.5,-15.0, -30.4, -74.0 and -96 ˚C. Little or none of the total sample water content froze at the -6.5 ˚C interval. The largest fraction of tissue water froze at about -15˚C, the next largest size fraction, of about 0.72 g/g,remained unfrozen until -30.4˚C. Lesser sized fractions of waters remained un frozen at variable lower temperatures. However,below a FP of -74˚C a distinct unfrozen water fraction of 0.20 to 0.28 g/g was observed in all eight of the samples surveyed. Five mechanisms are offered to help explain the water fractions that remain unfrozen at the different subzero temperatures.