氨甲环酸脂质体微泡复合物的制备及体外超声显影的初步研究

Preparation and Ultrasound Imaging of Tranexamic Acid Microbubble-liposome Compound

目的制备包封率高、稳定性好的氨甲环酸脂质体,并与微泡通过亲和素-生物素系统相连制备成脂质体微泡复合物,对该复合物的相关性质进行评价。材料与方法采用薄膜水化法制备氨甲环酸脂质体,以包封率为指标,通过正交试验优化制备流程,并与微泡相连接,制备脂质体微泡复合物,检测该复合物的基本表征特性,并通过超声显影及灰阶值测量评估声学特性。结果氨甲环酸脂质体制备优化组合为二棕榈酰磷脂酰胆碱、胆固醇、生物素酞化聚乙二醇2000修饰二硬脂酸磷酯酰乙醇胺摩尔比为85∶10∶5,氨甲环酸溶液5.0%,声振处理15 min,所得包封率为62.62%;粒径约为(104.00±1.84)nm,Zeta电位约(-50.50±0.56)mV,稳定性良好。氨甲环酸脂质体连接微泡所得复合物粒径约(4.56±0.28)μm,显微镜下呈圆形,中心透亮,分布较均匀,无黏附聚集。该复合物的体外声学特性主要表现为微泡的显影特点,这与显微镜下观察结果相符。随着复合物浓度的增加,其超声显影效果相应地增强,而具体量化的灰阶值也相应地增大。为避免声影的干扰,该复合物体外适宜超声显影浓度至少应低于1.15×108/ml。结论该实验以包封率为指标,优化了氨甲环酸脂质体微泡复合物的制备流程,并通过体外声学特性的评估为该复合物的超声有效示踪提供实验基础。

Purpose To prepare the tranexamic acid liposome with high encapsulation efficiency and stability, through interaction of avidin and biotin, and to prepare its microbubble-liposome compound whose properties are to be assessed. Materials and Methods Thin film hydration technology was used to prepare tranexamic acid liposome. Taking encapsulation efficiency as indication, the microbubble-liposome compound was optimized by the design of orthogonal experiment. The basic properties of the compound were tested and the acoustic characteristic was measured by ultrasound and gray-scale values. Results The optimum formula of tranexamic acid liposome were as follows： molar ratio of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine, cholesterol and 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[biotinyl （polyethylene glycol） 2000] was 85 ：10 ; 5; concentration oftranexamic acid was 5.0%; ultrasonic time was 15 min. The encapsulation efficiency was 62.62%. The size was approximately （104.00± 1.84）nm. The Zeta potential was approximately （-50.50±0.56） mV. The liposome was good in stability. The size of the microbubble-liposome compound was approximately （4.56±0.28） μm. Under the microscope, they were round with transparent center, evenly distributed without aggregation. The acoustic characteristic of the compound in vitro showed typical characteristics of microbubble, which was compatible with the results under the microscope. As the concentrations of the compound increased, both ultrasound imaging effect and the gray-scale values enhanced. However, to avoid acoustic shadows, the imaging concentrations were supposed to be at least lower than 1.15×10^8/ml in vitro. Conclusion The preparation of the tranexamic acid microbubble-liposome compound can be optimized by taking encapsulation efficiency as reference, and it can be effectively traced by ultrasound according to its acoustic characteristics in vitro.