Izutsu Ken-ichi, Rimando Annie, Aoyagi Nobuo, Kojima Shigeo
National Institute of Health Sciences, Japan.
Chem Pharm Bull (Tokyo). 2003 Jun;51(6):663-6. doi: 10.1248/cpb.51.663.
The effect of sodium tetraborate (Na(2)B(4)O(7), borax) on the thermal property of frozen aqueous sugar and polyol solutions was studied through thermal analysis. Addition of borax raised the thermal transition temperature (glass transition temperature of maximally freeze-concentrated solutes; T(g)') of frozen sucrose solutions depending on the borax/sucrose concentration ratios. Changes in the T(g)' of frozen mono- and disaccharide solutions suggested various forms of complexes, including those of a borate ion and two saccharide molecules. Borax exerted the maximum effect to raise the oligosaccharide and dextran T(g)'s at borax/saccharide molar ratios of approximately 1-2 (maltose and maltooligosaccharides), 2 (dextran 1060), 5 (dextran 4900), and 10 (dextran 10200). Further addition of borax lowered T(g)'s of the saccharide solutions. Borax also raised T(g) and T(g)' temperatures of frozen aqueous glycerol solutions. The decreased solute mobility in frozen solutions by the borate-polyol complexes suggested higher collapse temperature in the freeze-drying process and improved stability of biological systems in frozen solutions.
通过热分析研究了四硼酸钠（Na₂B₄O₇，硼砂）对冷冻糖水溶液和多元醇溶液热性能的影响。根据硼砂/蔗糖浓度比，添加硼砂会提高冷冻蔗糖溶液的热转变温度（最大冷冻浓缩溶质的玻璃化转变温度；T(g)'）。冷冻单糖和二糖溶液的T(g)'变化表明存在各种形式的复合物，包括硼酸根离子与两个糖分子形成的复合物。在硼砂/糖类摩尔比约为1-2（麦芽糖和麦芽低聚糖）、2（右旋糖酐1060）、5（右旋糖酐4900）和10（右旋糖酐10200）时，硼砂对提高寡糖和右旋糖酐的T(g)'效果最大。进一步添加硼砂会降低糖类溶液的T(g)'。硼砂还提高了冷冻甘油水溶液的T(g)和T(g)'温度。硼酸盐-多元醇复合物降低了冷冻溶液中溶质的流动性，这表明在冷冻干燥过程中具有更高的塌陷温度，并提高了冷冻溶液中生物系统的稳定性。
