载Fe_3O_4及液态氟碳高分子纳米粒的制备及其体外相变与双模态显影

Preparation of Fe_3O_4/PLGA/Perfluorohexane nanoparticles and its phase transformation in vitro for enhancing ultrasound and MR imaging

目的探讨载Fe3O4同时包裹液态全氟己烷（PFH）的高分子造影剂的制备并评价其体外相变与双模态显影能力。方法采用乳化法制备可相变的磁性造影剂,检测其粒径、电荷、表面形态及内部结构,对不同浓度的纳米粒溶液行MR扫描并用原子吸收光谱法测量各样品中Fe浓度;用加热法激发纳米粒相变,显微镜观察相变后产生的微泡,在造影模式下观察造影剂相变后增强超声显影能力。结果成功制备出可相变磁性Fe3O4/聚乳酸/羟基乙酸[PLGA]/PFH纳米粒。体外MR显像表明其能明显降低T2＊WI信号强度。当加热5min温度升高至55~65℃,纳米粒相变产生微泡,且可明显增强超声显影。结论制备的可相变磁性造影剂能明显降低T2＊WI信号强度,加热可发生相变,增强超声显影,可为多模态成像技术的发展奠定一定的实验基础。

Objective To prepare a perfluorohexane（PFH）-loaded phase-shift magnetic poly laetide-co-glycolide acid（PLGA）-nanoparticles,and explore its ability of phase transformation for enhancing dual-mode imaging in vitro.Methods Fe3O4/PLGA/PFH nanoparticles were prepared by modified emulsion method.The characteristics of nanoparticles（size distribution,Zeta potential and the morphology）were further examined.The nanoparticles of different concentrations were used for MR scanning,and the corresponding iron concentration was calculated.Temperature rise were applied to facilitate the phase transformation of nanoparticles.The microbubbles generated from the Fe3O4/PLGA/PFH nanoparticles were observed with the ultrasound in contrast mode.Results Fe3O4/PLGA/PFH nanoparticles for ultrasound and MR imaging were successfully prepared,which effectively decreased T2 signal.The MRI signal intensity decreased along with iron concentration increment.The Fe3O4/PLGA/PFH nanoparticles would undergo phase transformation and generate microbubbles after heated for 5min at 55—65℃.The generated microbubbles enhanced ultrasound imaging.Conclusion The developed phase-shift magnetic polymericnanoparticles can effectively decrease T2＊signal,which can be used as MRI contrast agent.Besides,the nanoparticles can produce microbbules and enhance ultrasound imaging after phase transformation.Therefore,it establishes the foundation for multi-mode imaging system.