Preparation and characteristics analysis of 5-carboxy fluorescein-dextran-coated superparamagnetic iron oxide nanoparticle

Abstract

Objective To investigate the physical and magnetic properties and cytotoxity of 5-FAM-dextran-coated superparamagnetic iron oxide nanoparticles (5-FAM-dextran-Fe3O4), and to observe the cell-labeling character of these nanoparticles. Methods 5-FAM-dextran-Fe3O4 were prepared by ultrasonic and chemical coprecipitation method and the characteristics were evaluated. The size and distribution of 5-FAM-dextran-Fe3O4 were measured by transmission electron microscope (TEM) and Malvern Zetasizer. The organic structure of the coating was characterized by fourier translation infrared spectroscopy. The optical imaging ability was measured by ultraviolet visible spectrometer and the susceptibility was measured by vibrating sample magnetometer. In vitro cytotoxities of 5-FAM-dextran-Fe3O4, dextran-Fe3O4 and Fe3O4 were detected by MTT assay. The area of labeled neuronal cells was observed by confocal microscopy after incubated with nanoparticles under different magnetic intensities. One-way analysis of variance was used. Results The size of 5-FAM-dextran-Fe3O4 was homogeneous under TEM, and the diameter ranged from 15 to 25 nm (average=22 nm) by Malvern Zetasizer. The organic structure of the coating of Fe3O4 was confirmed by fourier translation infrared spectroscopy. Ultraviolet visible spectrometer observation showed that the nanoparticles expressed unanimous green fluorescence under ultraviolet activation. The saturation magnetization, residual magnetization and coercivity of the nanoparticles by magnetometer detection were 86.02 A·m2·kg-1, 15.05 A·m2·kg-1 and 5 414.01 A/m respectively, showing superparamagnetic character. MTT assay results showed that 5-FAM-dextran-Fe3O4 had no obvious cytotoxicity. The confocal microscopy observation indicated that the cell-labeled area reached the maximum under the magnetic field intensity of 500 mT ((0.880±0.146) mm2,F=320.298, P<0.05). Conclusions 5-FAM-dextran-Fe3O4 prepared by ultrasonic coprecipitation method have the advantages of small size, good homogeneity and magnetic property. Therefore, they might be used as the fluorescent magnetic bio-probe in laboratory and clinical studies. Key words: Magnetite nanoparticles; Fluoresceins; Cells, cultured