Physics Department, Cornell University, Ithaca, NY 14853, USA.
Cryobiology. 2012 Dec;65(3):169-78. doi: 10.1016/j.cryobiol.2012.05.010. Epub 2012 Jun 19.
Ice formation on warming is of comparable or greater importance to ice formation on cooling in determining survival of cryopreserved samples. Critical warming rates required for ice-free warming of vitrified aqueous solutions of glycerol, dimethyl sulfoxide, ethylene glycol, polyethylene glycol 200 and sucrose have been measured for warming rates of order 10-10⁴ K/s. Critical warming rates are typically one to three orders of magnitude larger than critical cooling rates. Warming rates vary strongly with cooling rates, perhaps due to the presence of small ice fractions in nominally vitrified samples. Critical warming and cooling rate data spanning orders of magnitude in rates provide rigorous tests of ice nucleation and growth models and their assumed input parameters. Current models with current best estimates for input parameters provide a reasonable account of critical warming rates for glycerol solutions at high concentrations/low rates, but overestimate both critical warming and cooling rates by orders of magnitude at lower concentrations and larger rates. In vitrification protocols, minimizing concentrations of potentially damaging cryoprotectants while minimizing ice formation will require ultrafast warming rates, as well as fast cooling rates to minimize the required warming rates.
在确定冷冻保存样品的存活率方面，升温时的冰形成与降温时的冰形成同等重要，甚至更为重要。已经测量了甘油、二甲基亚砜、乙二醇、聚乙二醇 200 和蔗糖水玻璃化溶液在 10-10⁴ K/s 的升温速率范围内无冰升温所需的临界升温速率。临界升温速率通常比临界冷却速率大一个到三个数量级。升温速率与冷却速率强烈相关，这可能是由于名义上玻璃化的样品中存在小冰分。跨越速率数量级的临界升温和冷却速率数据为冰核形成和生长模型及其假定的输入参数提供了严格的测试。具有当前最佳输入参数估计值的当前模型合理地解释了高浓度/低速率下甘油溶液的临界升温速率，但在低浓度和大速率下，高估了临界升温和冷却速率的数量级。在玻璃化方案中，要最大限度地减少潜在有害保护剂的浓度，同时最大限度地减少冰的形成，需要超快的升温速率，以及快速的冷却速率以最小化所需的升温速率。
