Inhibition of Ice Growth and Recrystallization by Zirconium Acetate and Zirconium Acetate Hydroxide

The control over ice crystal growth, melting, and shaping is important in a variety of fields, including cell and food preservation and ice templating for the production of composite materials. Control over ice growth remains a challenge in industry, and the demand for new cryoprotectants is high. Naturally occurring cryoprotectants, such as antifreeze proteins (AFPs), present one solution for modulating ice crystal growth; however, the production of AFPs is expensive and inefficient. These obstacles can be overcome by identifying synthetic substitutes with similar AFP properties. Zirconium acetate (ZRA) was recently found to induce the formation of hexagonal cavities in materials prepared by ice templating. Here, we continue this line of study and examine the effects of ZRA and a related compound, zirconium acetate hydroxide (ZRAH), on ice growth, shaping, and recrystallization. We found that the growth rate of ice crystals was significantly reduced in the presence of ZRA and ZRAH, and that solutions containing these compounds display a small degree of thermal hysteresis, depending on the solution pH. The compounds were found to inhibit recrystallization in a manner similar to that observed in the presence of AFPs. The favorable properties of ZRA and ZRAH suggest tremendous potential utility in industrial applications.

对冰晶生长、熔融与形貌的调控在诸多领域均具有重要价值，涵盖细胞与食品保鲜，以及用于复合材料制备的冰模板法（ice templating）领域。当前工业界仍面临冰晶生长调控的核心难题，新型低温保护剂的市场需求十分旺盛。天然存在的低温保护剂，例如抗冻蛋白（antifreeze proteins, AFPs），为调控冰晶生长提供了可行方案；但抗冻蛋白的制备成本高昂且效率低下。若能开发出具备抗冻蛋白相似特性的合成替代物，便可攻克上述技术瓶颈。近期研究发现，醋酸锆（Zirconium acetate, ZRA）可在冰模板法制备的材料中诱导形成六边形空腔。本研究延续该研究方向，探究了醋酸锆及其相关化合物醋酸羟锆（zirconium acetate hydroxide, ZRAH）对冰晶生长、形貌与再结晶的影响。实验结果表明，醋酸锆与醋酸羟锆均可显著降低冰晶生长速率，且含该类化合物的溶液会呈现出程度不一的热滞后效应，其效应强弱取决于溶液pH值。研究发现，这两种化合物可通过与抗冻蛋白类似的机制抑制冰晶再结晶。醋酸锆与醋酸羟锆的优良特性表明其在工业应用中具备极高的应用潜力。