X-Message-Number: 24458
Date: Mon, 2 Aug 2004 20:06:52 -0700 (PDT)
From: Doug Skrecky <>
Subject: diethylsulphoxide, a new and  superior cryoprotectant?

Cryobiology. 2004 Aug;49(1):1-9.
Glass-forming property of the system diethyl sulphoxide/water and its
cryoprotective action on Escherichia coli survival.
  In this work the thermal properties of diethyl sulphoxide (Et(2)SO), as
well as its cryoprotective ability are studied and related to other
well-known cryoprotectant substances, like dimethyl sulphoxide (Me(2)SO).
We have investigated the thermal properties of Et(2)SO/water systems
using Differential Scanning Calorimetry at a very low heating/cooling rate
(2 degrees C/min). Liquid/solid or glassy/crystalline transitions have
been observed only for the solutions with content of Et(2)SO ranging from
5 up to 40% w/w and/or greater than 85%. In the 45-75% w/w Et(2)SO range
we have found a noticeable glass-forming tendency and a great stability of
the amorphous state to the reheating. In samples with Et(2)SO content
ranging from 80 to 85%, we observed a great stability of the glass
forming by cooling, but a lesser stability to the subsequent reheating.
The glass-forming tendency of these solutions is discussed in terms of
existing competitive interactions between molecules of Et(2)SO, on the
one hand, and Et(2)SO and water molecules, on the other hand. The results
are well explainable on the basis of the model structure of water/Et(2)SO
solutions, deduced by Raman and infrared studies [J. Mol. Struct. 665
(2003) 285-292]. The cryoprotective ability of Et(2)SO on Escherichia
coli survival has been also investigated, and a comparison among Et(2)SO
and other widely used cryoprotectants, like Me(2)SO and glycerol has been
done. Survival of E. coli, determined after freezing-thawing process, was
maximal at 45% w/w Et(2)SO (more than 85% viability). It should be noted
that at the same concentration the survival is only about 35% in the
presence of Me(2)SO and not more than 15% in the presence of glycerol.
These features are well consisted with the glass-forming properties of

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