Shimokawa Ken-ichi, Saegusa Katsuhiko, Ishii Fumiyoshi
Department of Pharmaceutical Sciences, Meiji Pharmaceutical University, 2-522-1 Noshio, Kiyose, Tokyo, 204-8588, Japan.
Colloids Surf B Biointerfaces. 2009 Nov 1;74(1):56-8. doi: 10.1016/j.colsurfb.2009.06.022. Epub 2009 Jun 23.
The influences of various salts and water-soluble polymers on the phase transition temperature of thermo-setting gels prepared by combining methylcellulose (MC)-sodium citrate (SC)-polyethylene glycol (PEG) at appropriate ratios (the MC-SC-PEG system) were investigated. Concerning cations, comparison of the phase transition temperature between SC and tripotassium citrate (PC) showed a rapid increase in the viscosity of SC between 20 degrees C and 25 degrees C and an increase in the viscosity of PC between 30 degrees C and 35 degrees C. Concerning the valency of anions, comparisons among SC, disodium tartrate dihydrate (ST), disodium maleate hemihydrates (SM), and sodium sulfate (SS) showed a rapid increase in the viscosity of trivalent SC between 20 degrees C and 25 degrees C and changes in the viscosity of the three bivalent sodium salts (ST, SM, and SS) at > or =30 degrees C. Thus the phase transition temperature decreased with an increase in the valency of anions. Subsequently, the influences of various water-soluble polymers on the gelling temperature were compared. Using polyvinylpyrrolidone (PVP) instead of PEG, the gelling temperature decreased with an increase in the PVP concentration even without the addition of SC. Unlike PVP, the addition of xanthan gum as a viscosity-increasing polysaccharide did not reduce the gelling temperature irrespective of its concentration. Temperature-associated changes in viscosity were observed at a fixed SC concentration with changes in the concentration of PVP or PEG. The gel phase transition temperature increased from 46 degrees C to 50 degrees C in gels not containing PVP or PEG. The viscosity did not differ between the addition of PVP or PEG at a low concentration and its absence. However, the viscosity clearly changed after the addition of each agent at a high concentration.
研究了各种盐和水溶性聚合物对通过以适当比例混合甲基纤维素（MC）-柠檬酸钠（SC）-聚乙二醇（PEG）制备的热固性凝胶（MC-SC-PEG体系）的相变温度的影响。关于阳离子，比较SC和柠檬酸钾（PC）之间的相变温度，结果显示SC在20℃至25℃之间粘度迅速增加，而PC在30℃至35℃之间粘度增加。关于阴离子的价态，比较SC、二水合酒石酸二钠（ST）、半水合马来酸二钠（SM）和硫酸钠（SS），结果显示三价SC在20℃至25℃之间粘度迅速增加，而三种二价钠盐（ST、SM和SS）在≥30℃时粘度发生变化。因此，相变温度随着阴离子价态的增加而降低。随后，比较了各种水溶性聚合物对胶凝温度的影响。用聚乙烯吡咯烷酮（PVP）代替PEG，即使不添加SC，胶凝温度也随着PVP浓度的增加而降低。与PVP不同，添加黄原胶作为增粘多糖，无论其浓度如何，都不会降低胶凝温度。在固定的SC浓度下，随着PVP或PEG浓度的变化，观察到粘度随温度的变化。不含PVP或PEG的凝胶的凝胶相变温度从46℃升高到50℃。低浓度添加PVP或PEG与不添加时粘度没有差异。然而，高浓度添加每种试剂后，粘度明显变化。
