Bonacucina Giulia, Palmieri Giovanni F, Craig Duncan Q M
Department of Chemical Sciences, University of Camerino, Via S. Agostino 1, I-62032 Camerino (MC), Italy.
J Pharm Sci. 2005 Nov;94(11):2452-62. doi: 10.1002/jps.20446.
A series of glyceryl monoolein/water gel systems containing 10%, 22%, and 30% w/w water has been investigated using two complementary techniques, oscillatory rheology and dielectric analysis, in order to establish the utility of these two techniques in conjunction and to investigate the influence of the inclusion of a model peptide, cyclosporin A, on the properties of the gels. Oscillatory rheology was performed in two modes; frequency sweeps at 20, 37, and 70 degrees C and temperature sweeps from 20 to 70 degrees C. Dielectric spectroscopy was performed in the kHz to mHz frequency range over a temperature range of 20-70 degrees C. Both rheology and dielectric spectroscopy were able to identify structural changes in the systems analyzed, with the 10% and 30% (w/w) water sample showing typical features of the lamellar and cubic phase respectively at 20 degrees C, while the 22% (w/w) system showed intermediate behavior. The thermotropic phase transitions could be monitored using rheological temperature sweeps. Drug loading resulted in marked changes in rheological and dielectric response of the 10% w/w water system, causing a decrease in both elasticity and permittivity values, while a less marked effect was observed for the 22% and, in particular, the 30% w/w systems. The investigation has demonstrated that rheological and dielectric measurements yield distinct yet complementary information and that the inclusion of a model peptide may alter the properties of the gel, the extent of the effect being dependent on the phase composition of the system.
一系列含有10%、22%和30%（重量/重量）水的甘油单油酸酯/水凝胶体系已通过两种互补技术——振荡流变学和介电分析进行了研究，目的是确定这两种技术结合使用的效用，并研究添加模型肽环孢素A对凝胶性质的影响。振荡流变学以两种模式进行；在20、37和70摄氏度下进行频率扫描，以及在20至70摄氏度范围内进行温度扫描。介电谱在20 - 70摄氏度的温度范围内，在千赫兹至毫赫兹频率范围内进行。流变学和介电谱都能够识别所分析体系中的结构变化，10%（重量/重量）和30%（重量/重量）水的样品在20摄氏度时分别表现出层状相和立方相的典型特征，而22%（重量/重量）的体系表现出中间行为。热致相变可以使用流变温度扫描进行监测。药物负载导致10%（重量/重量）水体系的流变学和介电响应发生显著变化，导致弹性和介电常数降低，而对于22%，特别是30%（重量/重量）的体系，观察到的影响较小。该研究表明，流变学和介电测量产生了不同但互补的信息，并且添加模型肽可能会改变凝胶的性质，影响程度取决于体系的相组成。
