Flory temperature and upper critical solution temperature of gelatin solutions
Flory temperature and upper critical solution temperature of gelatin solutions
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DOI：
10.1021/bm0492430
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发表时间：
2005-05-01
影响因子：
6.2
通讯作者：
Bohidar, HB
中科院分区：
文献类型：
--
作者：
Gupta, A;Mohanty, B;Bohidar, HB
通过对明胶溶液进行浊度实验测得的弗洛里温度 (theta)，对于盐浓度 0.1、0.075、0.05、0.025 和 0 M (NaCl)，分别为 12 +/- 0.3、13 +/- 0.3、14 +/- 0.3、14.5 +/- 0.3 和 15 +/- 0.3 摄氏度。这种弱电荷聚电解质的估计持久长度 (l(p)) 可以从 Benoit 和 Doty (J. Phys. Chem. 1953, 57, 958) 关系中推导出来，该关系与该生物聚合物在弗洛里温度下呈现紧凑的近球形形状，意味着 l(p) = 9(R-h)(2)/(5L(m))，其中 L-m 是轮廓长度和 R-h 是流体动力学半径。结果发现，在室温（20 摄氏度）下，l(p) 近似于 2.2 +/- 0.2 nm，且盐浓度不变。发现弗洛里膨胀系数 (alpha = R-h(T)/R-h(theta) = 1.5 +/- 0.2）几乎恒定。该生物聚合物的θ-组成是通过使用醇类甲醇、乙醇、2-丙醇和叔丁醇对明胶水溶液进行比浊滴定推导出来的。看来疏水相互作用在θ温度和组成下引起链塌陷中起着至关重要的作用。
The Flory temperatures (theta) measured by turbidity experiments performed on gelatin solutions were found to be 12 +/- 0.3, 13 +/- 0.3, 14 +/- 0.3, 14.5 +/- 0.3, and 15 +/- 0.3 degrees C for salt concentrations 0.1, 0.075, 0.05, 0.025, and 0 M (NaCl), respectively. Estimated persistence length (l(p)) of this weakly charged polyelectrolyte could be deduced from the Benoit and Doty (J. Phys. Chem. 1953, 57, 958) relationship with the approximation that this biopolymer assumes a compact near-globular shape at Flory temperature, implying l(p) = 9(R-h)(2)/(5L(m)), where L-m is the contour length and R-h is the hydrodynamic radius. It was found that l(p) approximate to 2.2 +/- 0.2 nm at room temperature (20 degrees C), invariant of salt concentration. The Flory expansion factor (alpha = R-h(T)/R-h(theta) = 1.5 +/- 0.2) was found to be almost constant. theta-Composition for this biopolymer was deduced from turbidimitric titration of aqueous gelatin solutions with the alcohols methanol, ethanol, 2-propanol, and tert-butyl alcohol. It appears that hydrophobic interactions play a crucial role in causing chain collapse at theta-temperature and composition.