X-Message-Number: 15527
Date: Thu, 1 Feb 2001 23:19:01 -0800 (PST)
From: Doug Skrecky <>
Subject: Vitrification enhancement by synthetic ice blocking agents

  Wowk B.  Leitl E.  Rasch CM.  Mesbah-Karimi N.  Harris SB.  Fahy GM.
  21st Century Medicine, Inc., Rancho Cucamonga, CA 91730, USA. 
  Vitrification enhancement by synthetic ice blocking agents.
  Cryobiology.  40(3):228-36, 2000 May.
  Small concentrations of the synthetic polymer polyvinyl alcohol (PVA) were
  found to inhibit formation of ice in water/cryoprotectant solutions. Ice
  inhibition improved with decreasing molecular weight. A PVA copolymer of
  molecular weight 2 kDa consisting of 20% vinyl acetate was found to be
  particularly effective. PVA copolymer concentrations of 0.001, 0.01, 0.1, and
  1% w/w decreased the concentration of glycerol required to vitrify in a 10-ml
  volume by 1, 3, 4, and 5% w/w, respectively. Dimethyl sulfoxide
  concentrations required for vitrification were also reduced by 1, 2, 2, and
  3% w/w, respectively. Crystallization of ice on borosilicate glass in contact
  with cryoprotectant solutions was inhibited by only 1 ppm of PVA copolymer.
  Devitrification of ethylene glycol solutions was also strongly inhibited by
  PVA copolymer. Visual observation and differential scanning calorimeter data
  suggest that PVA blocks ice primarily by inhibition of heterogeneous
  nucleation. PVA thus appears to preferentially bind and inactivate
  heterogeneous nucleators and/or nascent ice crystals in a manner similar to
  that of natural antifreeze proteins found in cold-hardy fish and insects.
  Synthetic PVA-derived ice blocking agents can be produced much less
  expensively than antifreeze proteins, offering new opportunities for
  improving cryopreservation by vitrification. Copyright 2000 Academic Press.

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