动态流变实验评价温敏凝胶的方法研究

 目的应用动态流变实验测定温度敏感原位凝胶的流变性质,以预测其在体胶凝(相变)行为。方法以泊洛沙姆407 (P407)为基质制备地塞米松温度敏感原位凝胶(DSP-gel)。采用动态流变实验测定DSP-gel在不同温度下及相变过程中的流变参数,并与P407相比较。应用差示扫描量热法(DSC)测定DSP-gel胶凝温度。结果DSP-gel在低温时为黏弹性流体,温度升到27℃时开始胶凝,并在体温条件下保持凝胶状态。相转变表现为模量呈指数增长,全部过程约在7℃内完成。DSC测得相变温度为26.58℃,与流变学得到结果一致。结论动态流变实验能表征温敏凝胶的黏弹性流体力学性质,可用于体外评价。

Evaluation of Thermosensitive in Situ Gel Using Dynamic Rheological Experiment

OBJECTIVE To characterize the theological properties of thermosensitive in situ gel for better understanding the process of thermal gelification in situ.METHODS Dexamethasone sodium phosphate-loaded thermosensitive in situ gel(DSP-gel) was prepared using puloxamer 407 as material.Dynamic rheological experiments provided information on the dynamic properties,such as elasticity modulus and viscosity modulus,by investigating the stress response of the gel subjected to a sinusoidally varying strain. The measurements of the theological parameters for poloxamer 407 and DSP-gel were made at 17 or 37℃.And the phase transition process from liquid to semisolid was described via the increment in the parameters.Heating curve of DSP-gel gelation process was esti- mated by employing differential scanning calorimetery(DSC).RESULTS Poloxamer 407 and DSP-gel were free flowing viscoelastic liquid at room temperature and converted to a firm gel at 27℃and possessed the highest viscosity under the physiological temperature. The sol-gel transition process was completed at about 7℃and exhibited exponential increase of the modulus with temperature.And the value of the phase transition temperature obtained by DSC was 26.58℃,the same as the result that dynamic rheological experiments determined.CONCLUSION Dynamic rheological experiments can provide scientific information on the viscoelastic hydrodynamic properties of thermosensilive in situ gel for in vitro evaluation.