新型纳米微泡超声造影剂的制备及超声显像研究

Preparation and Ultrasonic Imaging of Novel Nanoscale Bubble Ultrasound Contrast Agent

【目的】制备可稳定显像的新型小粒径纳米级超声微泡造影剂,并评价其体内外超声显像效果。【方法】通过薄膜-水化、声振-通气及多级分离等多步骤方法制备纳米级脂质微泡,并针对制备过程中的主要影响因素设计了正交试验,筛选出粒径小、重复性好的实验条件。通过光学显微镜及Zeta粒径仪检测纳米微泡大小形态、粒径分布,体外及动物体内超声显像检测其增强显像效果。【结果】纳米脂质微泡呈圆形,分布均匀,无明显聚集,粒径范围238.6～340.7nm,均值为(276.0±24.1)nm,Zata电位:(-14.0±0.6)mV。体外超声检测在超声造影状态下能持续稳定显像,进入到二维灰阶状态时,瞬间破坏完全,显像效果消失,粒径变小。体内超声显像在造影状态下纳米微泡可明显增强大鼠肝脏、肾脏回声信号。【结论】通过本研究方法成功制备了粒径小、可稳定显像的新型纳米级超声造影剂,在二维灰阶高机械指数状态下该纳米微泡造影剂可被瞬间破坏,这为进一步肿瘤组织血管外靶向显像及肿瘤局部药物释放研究奠定基础。

[Objective] To prepare and optimize nanoscale bubble ultrasound contrast agent for stable ultrasonic imaging,and to evaluate its enhancing imaging capability in vitro and in vivo.[Methods] Nanoscale bubbles were prepared by multiple-step methods：film-hydration,sonication and ventilation,low-speed centrifugal classifier.In order to screen out the optimal experimental conditions for small diameter and good repeatability,orthogonal test was designed aimed to main factors.The bubble morphology was observed under light microscopy,the nanobubble size was assessed by the Zeta 90Plus/BI-MAS Brookhaven.The contrast enhancement effect was observed in vitro and in vivo.[Results]Nanoscale bubbles with spherical shape distributed homogeneously,without obvious aggregation.The range of diameters was（238.6-340.7） nm,with the mean diameters of（276.0 ± 24.1） nm and average zeta potential of（-14.0 ± 0.6） mV.In vitro test in CPS mode nanoscale bubbles showed stable imaging.When turned to grayscale mode with high mechanical index,the bubbles were destroyed immediately with smaller diameters,and the enhancement of the image receded.Contrast imaging in vivo showed that the nanoscale ultrasound contrast agent could significantly enhance echo intensity of the vessels and parenchyma in rat livers and kidneys.[Conclusion]This kind of novel stable and small size nanoscale ultrasound contrast agent,which were easily destroyed in gray-scale mode with high mechanical index,would lay a foundation for extravascular tumor targeting imaging and local drug delivery.