ICG磁性PLGA纳米粒的制备及其在小鼠体内的脑靶向作用

Preparation and Brain Targeting in Mice of Magnetic PLGA Nanoparticles Loaded with ICG

目的:制备装载近红外荧光探针吲哚菁绿(ICG)的磁性聚乳酸-羟基乙酸共聚物(PLGA)纳米探针,并利用小动物活体成像技术观察ICG磁性PLGA纳米粒的脑靶向作用。方法:取ICG、PLGA和四氧化三铁纳米颗粒采用纳米沉淀法制备ICG磁性PLGA纳米粒,采用激光粒度分析仪检测其粒径、聚合物分散性指数(PDI)及Zeta电位分布,采用透射电镜观察其外貌和粒径大小,采用紫外可见吸收光谱法和原子吸收分光光度法测定ICG和四氧化三铁纳米粒的包封率和载药量;取NOD/SCID gamma(NSG)小鼠4只,其中头部放置和不放置磁铁各2只,同时尾静脉注射ICG磁性PLGA纳米粒后,采用小动物荧光成像仪观察活体及取脑前后活体动物、离体脑部的荧光成像,并利用系统自带的分子成像软件对离体脑部的近红外荧光进行定量分析。结果:本实验制备得到球形ICG磁性PLGA纳米粒,粒径为(172.77±2.14)nm,PDI为(0.225±0.015),Zeta电位为(-4.18±0.67)m V,ICG和四氧化三铁纳米粒的包封率分别为61.8%和40.1%,载药量分别为0.165%和0.042%;小动物活体荧光成像仪结果显示,ICG磁性PLGA纳米粒在磁场作用1 h后向NSG小鼠头部聚集;取脑部组织定量分析结果表明,经磁场作用的ICG磁性PLGA纳米粒在NSG小鼠头部的荧光强度约为无磁场作用NSG小鼠的1.2倍。结论:成功制备得到符合动物实验要求的球形ICG磁性PLGA纳米粒,且在磁场作用下具有一定的脑靶向作用。

Objective:A new kind of magnetic nanoparticles loaded with near-infrared fluorescent probe,indocyanine green(ICG),was prepared using polylactic-co-glycolic acid(PLGA)copolymer as carriers.Its brain targeting driven by the magnetic force was observed using vivo imaging technology in small animals.Methods:The magnetic PLGA nanoparticles loaded with ICG(ICG-PLGA MNPs)were synthesized by the nanoprecipitation method using ICG,PLGA and Fe3 O4 nanoparticles.The size,PDI and Zeta potential of ICG-PLGA MNPs were detected by the dynamic light scattering analyzer.The morphology and size of ICG-PLGA MNPs were observed under the transmission electron microscopy.The encapsulation efficiency and drug loading of ICG and Fe3 O4 nanoparticles were determined by the UV-VIS absorption spectrometry and atomic absorption spectrophotometry,respectively.Four NOD/SCID gamma(NSG)mice were taken,two of which were placed with or without a magnet on the head,and injected with ICG magnetic PLGA nanoparticles by tail vein at the same time.All the fluorescent images of mice and isolated brain were captured by a Bruker In-Vivo Xtreme imaging system and the near-infrared fluorescence of isolated brain was quantitatively analyzed by the Molecular Imaging Software in the imaging system.Results:The spherical ICG-PLGA MNPs were successfully prepared in this experiment.The particle size was(172.77±2.14)nm,PDI was(0.225±0.015),and Zeta potential was(-4.18±0.67)m V.The encapsulation efficiency of ICG and Fe3 O4 nanoparticles were 61.8%and 40.1%,and the drug loading was 0.165%and 0.042%,respectively.Through the observation through the Bruker In-Vivo Xtreme imaging system,under the magnetic field 1 h later,ICG-PLGA MNPs gathered to the head of NSG mice.For the quantitative analysis,the brain tissues were taken out.The fluorescence intensity of ICG magnetic PLGA nanoparticles in the head of NSG mice with the magnetic field was about 1.2 times that in the head of NSG mice without the magnetic field.Conclusion:The spherical ICG magnetic PLGA nanoparticles are successfully established and used for the animal experiments,which verifies the function of the brain targeting of ICG-PLGA MNPs.