2种聚乙二醇不饱和酸单酯共聚合包被Fe3O4制备磁性微球及其表征

Preparation and characterization of magnetic microspheres coated with copolymers of two unsaturated monoesters of poly（ethylene glycol）

摘要:

目的：用两种聚乙二醇（Polyethylene glycol，PEG）不饱和酸单酯经自由基共聚包被纳米Fe3O4磁芯制备磁性微球，考察其功能化后特异性和非特异性结合作用。方法：水解沉淀法制备纳米Fe3O4磁芯；用PEG-350单甲醚丙烯酸酯和PEG-1540单顺丁烯酸单酯为单体，在正庚烷-水组成的油包水体系自由基共聚制备磁性微球；将微球表面来自PEG-1540的羟基经甲磺酸酯活化、连接乙二胺后再用活化生物素修饰。透射电镜观察其外貌；测定与碱性磷酸酶标记链亲和素（Streptavidin labeled by alkaline phosphate，AP-SAV）的特异性结合、与4-硝基-1-萘酚苯甲酸酯等的非特异性结合。结果：所得Fe3O4粒径60 nm左右，生物素修饰后粒径接近200 nm。此磁性微球可从混合蛋白中选择性分离碱性磷酸酶酶标记的链亲和素，结合容量约51 ng蛋白/g磁性微球；4-硝基-1-萘酚苯甲酸酯在浓度很低时同此磁性微球的结合低于检测限，在浓度高达64 ?滋mol/L时仍无显著结合。结论：用两种PEG不饱和酸酯共聚包被Fe3O4可制备表面亲水磁性微球，功能化后有特异相互作用且非特异性作用很弱，但还需提高此磁性微球功能化后的特异性结合容量。

Abstract:

Objective：To prepare and characterize magnetic microspheres coated with copolymers of two unsaturated esters of Polyethylene glycol（PEG）. Methods：Fe3O4 nanoparticles were prepared by a chemical co-precipitation method.Magnetic microspheres were prepared by coating Fe3O4 cores with copolymers of monomethoxyl-PEG 350 acrylate and the single maleic acid ester of PEG 1540. Hydroxyl groups on the surfaces were converted to methanesulfonate that was reacted with ethylene diamine；the resulting amino groups were modified with an activated biotin ester. Microsphere sizes were examined by transmission electronic microscopy. The specific bindings were tested with streptavidin labeled by alkaline phosphatase；the nonspecific bindings were tested with 4-nitro-1-naphthylol benzoate and analyzed via HPLC-UV. Results：Fe3O4 cores had the diameters of about 60 nm with wide distributions while the biotinylated magnetic microspheres had the diameters of about 200 nm. The biotinylated magnetic microspheres selectively recov－ered the labeled streptavidin from the lysate of E.coli with a binding capacity of about 51 ng protein/g magnetic microspheres.4-nitro-1-naphthylol benzoate at low concentrations had negligible bindings; its binding ratio increased but still had no significance even at 64 μmol/L. Conclusion：Hydrophilic magnetic microspheres prepared by coating Fe3O4 cores with copolymers of two unsaturated es－ters of PEG can be functionalized to exert the designed specific interactions while negligible nonspecific interactions with hydrophobic compounds，but the binding capacity needs further enhancement.