X-Message-Number: 8429
From: Brian Wowk <>
Date: Thu, 31 Jul 1997 20:52:52 -0500 (CDT)
Subject: Melting points, etc.

	Regarding the recent questions about the melting point
of adonitol: It is generally true in chemistry that when you mix two
compounds together, the resultant solution has a melting point lower
than that of either component.  For example, pure glycerol and DMSO
have melting points close to room temp.  But 65% solutions in water
don't solidify until somewhere near -100'C.  So a high melting
point does not immediately disqualify an agent as a cryoprotectant.

	About adonitol in particular, adonitol (1,2,3,4,5 penta-
hydroxypentane) is a huge molecule that costs $2 per gram.
Although I haven't consulted Doug's permeability reference
yet, it's almost certainly going to be less permeant and
more viscous than glycerol.  And glycerol is already almost
intolerably viscous and non-permeant for cryoprotection by
perfusion (as distinct from cryoprotection of cell suspenstions
in solution).

***************************************************************************
Brian Wowk          CryoCare Foundation               1-800-TOP-CARE
President           Human Cryopreservation Services   
   http://www.cryocare.org/cryocare/
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