包裹液态氟碳高分子纳米球相变及体外超声显影

目的制备一种新型纳米级超声造影剂——液态氟碳（PFP）高分子纳米球，观察其物理特性、体外热致相变、声致相变及体外超声显影效果。方法采用乳化一蒸发法（单乳化法）制备包裹PFP的MPEG-PLGA纳米球（P-NP），以光镜观察纳米球形态分布，以纳米粒度及Zeta电位分析仪检测纳米球粒径和电位；在显微镜上放置加热板实时观察P-NP的相变情况；于体外应用低强度聚焦超声（LIFU）仪辐照后，观察其超声显影效果。结果所制备的包裹PFP的高分子纳米球外观为乳白色混悬液，形态规则，呈球包球形；平均粒径为（393．2±40．7）nm，平均电位为（-5．23±8．69）mV；加热板显示的温度约为42．6℃时，光镜下显示纳米球开始转变为微气泡，且随着温度增高，所产生的气泡逐渐增多；体外行LIFU辐照后，在超声基波和谐波模式下可观察到显影明显增强。结论成功制备了PFP高分子纳米球，其粒径小、稳定性好，体外经LIFU仪辐照后可增强超声显影，有望成为一种新型超声造影剂。

Phase change of polymeric nanocapsules with liquid perfluorocarbons and in vitro ultrasound imaging

Objective To prepare a new ultrasound contrast agent polymeric nanocapsules of liquid perfluorocarbons （P- NP）, and to observe its physical characteristics, phase change by heating or ultrasound and effect on ultrasound imaging in vitro. Methods P-NP was prepared by using emulsion solvent-evaporation process. The morphology and distribution were observed with optical microscope. The size and electric potential were obtained by using nano-zetasizer. The phase change of nanocapsules of liquid perfluorocarbons on heatingplate was observed by optical microscope instantaneously. After using low intensity focused ultrasound （LIFU）, the effect on ultrasound imaging was observed in vitro. Results The prepared polymeric nanocapsules of PFP was opacified suspension in appearance, the distribution and size were uniformed with core- shell structure, with the average size and potential of （393.2± 40.7） nm and （ -- 5.23 ± 8.69） mV, respectively. When heatingplate showed 42.6℃, the phase change of nanocapsules had just begun, and the higher the temperature was, the more bubbles formed. After LIFU ablation, P-NP of obvious enhancement of ultrasound imaging was observed under the model of fundamental and harmonic wave in vitro. Conclusion P-NP can be successfully prepared using the above method, and can enhance ultrasound imaging after LIFU ablation in vitro, which may become a new type of ultrasound contrast agent.