纳米尺度超声显影微囊的制备及性能表征简

采用双乳液-溶剂挥发法制备了内部包封氟碳液体的聚乳酸-甲氧基聚乙二醇两嵌段共聚物(MePEG-b-PLA)基超声显影纳米微囊；用2种不同嵌段比的MePEG-b-PLA共聚物研究共聚物组成与纳米囊性能的关系；选用聚乙烯醇(PVA)、羧甲基葡聚糖(CMG)和壳聚糖(CS) 3种乳化剂对纳米囊表面进行亲水性修饰. 对所制备纳米囊的粒径、Zeta电位、形貌和水溶液稳定性进行了表征. 结果表明，利用质量分数为1%的PVA和质量分数为1%的CMG组成的复配乳化剂和m(MePEG)：m(PLA)= 1：3的聚合物制得的纳米囊的平均粒径为432.9 nm，水溶液稳定性优良. 利用超声仪对纳米囊体外超声显影性能进行研究，结果表明，所得聚乳酸-甲氧基聚乙二醇纳米囊具有更好的中心成像区域灰度值和更持久的体外超声显影效果. 结合3-(4，5-二甲基噻唑-2)-2，5-二苯基四氮唑溴盐(MTT)比色法研究证实该纳米囊具有低细胞毒性. 在超声影像学领域具有良好的应用前景.

Fabrication and Medical Imaging of Ultrasonic Imaging Nanocaspsules

Poly(lactic acid)-b-poly(ethylene glycol)(MePEG-b-PLA) based nanocapsules containing per-fluorohexane were fabricated through a double emulsion-solvent evaporation method. In the preparation, three kinds of hydrophilic polymers, i.e., poly(vinyl-alcohol)(PVA), chitosan(CS), and carboxymethyl dextran(CMG) were used as emulsifier or co-emulsifier to modify the surface of nanocapsules. Besides, two kinds of MePEG-b-PLA copolymers with different block length ratio were used as main shell composition to fabricate nanocapsules. Nanocapsule size, morphology, zeta potential, water stability of six nanocapsule samples fabricated by different polymers or emulsifiers were characterized by Malvern nanosizer analyzer, transmission electron microscope(TEM) and UV-Visible spectrophotometer(UV-Vis), respectively. The results showed that nanocapsules using 1%PVA+1%CMG as an emulsifier and MePEG-b-PLAm(MePEG):m(PLA)=1:3]as shell material had monodispersed small size and stable water property. These nanocapsules are not only in nanometer-scale but also possess favorable ultrasonic imaging property. Ultrasonic imaging property of nanocapsules was charaeterized using in vitro ultrasound tester and made a comparison with a commercialized ultrosonic imaging agent SonoVueTM. The results demonstrated a brighter contrast scale and edurable ultrasonic property of MePEG-b-PLA nanocapsules. In addition, the cytotoxicity by incubating MePEG-b-PLA nanocapsules with rat liver cells line BRL-3A was characterized through 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide(MTT) assay. The results showed that the PLA-based nanocapsules imposed no significant inhibition effect on proliferation of BRL-3A cells.