Department of Food Science, Rutgers, The State University of New Jersey, 65 Dudley Road, New Brunswick, New Jersey 08901-8520, United States.
J Agric Food Chem. 2011 Apr 13;59(7):3340-7. doi: 10.1021/jf1041432. Epub 2011 Mar 7.
Molecular mobility in amorphous solid biomaterials is modulated by the composition and environment (primarily temperature). Phosphorescence of the triplet probe erythrosin B was used to generate a mobility map within amorphous sucrose films doped with starch ranging from 0.001 to 0.1 g starch/g sucrose. Data on the emission energy and lifetime of erythrosin B in sucrose and sucrose-starch films over the temperature range from 5 to 100 °C indicates that starch influences the molecular mobility as well as dynamic site heterogeneity of amorphous sucrose in a dose-dependent manner. At a starch/sucrose weight (wt) ratio below 0.005, both emission energy and lifetime decreased, and both the dipolar relaxation rate and nonradiative quenching rate k(TS0) increased, indicating that starch increased the matrix molecular mobility. At a ratio above 0.005, both emission energy and lifetime increased, and the dipolar relaxation rate and nonradiative quenching rate decreased, indicating that starch decreased the matrix mobility both in the glass and in the melt. The mobility showed a minimum value at a ratio of 0.01. The interactions existing in the sucrose-starch matrix are considered as the determining factor to influence the molecular mobility of sucrose-starch mixtures. Changes in the distribution of emission energies (emission bandwidth) and lifetimes indicated that starch increased the spectral heterogeneity at high contents while showing insignificant change or a slight decrease in the heterogeneity at low starch contents. These data illustrate the complex effects of a polymer with mainly linear structure and flexible conformation on the mobility of an amorphous, hydrogen bonded sugar matrix.
无定形固体生物材料中的分子迁移率受组成和环境（主要是温度）的调节。使用三重态探针曙红 B 的磷光来生成在掺杂有淀粉的无定形蔗糖膜内的迁移率图谱，淀粉的浓度范围从 0.001 到 0.1g 淀粉/g 蔗糖。在 5 到 100°C 的温度范围内，关于曙红 B 在蔗糖和蔗糖-淀粉膜中的发射能量和寿命的数据表明，淀粉以剂量依赖的方式影响无定形蔗糖的分子迁移率和动态局部异质性。在淀粉/蔗糖重量（wt）比低于 0.005 的情况下，发射能量和寿命都降低了，偶极弛豫速率和非辐射猝灭速率 k(TS0)都增加了，这表明淀粉增加了基质分子迁移率。在比例高于 0.005 的情况下，发射能量和寿命都增加了，而偶极弛豫速率和非辐射猝灭速率降低了，这表明淀粉降低了玻璃态和熔融态基质的迁移率。在比例为 0.01 时，迁移率达到最小值。蔗糖-淀粉基质中存在的相互作用被认为是影响蔗糖-淀粉混合物分子迁移率的决定因素。发射能量（发射带宽）和寿命分布的变化表明，在高含量时，淀粉增加了光谱异质性，而在低淀粉含量时，异质性没有明显变化或略有降低。这些数据说明了主要具有线性结构和柔性构象的聚合物对无定形氢键糖基质的迁移率的复杂影响。
