ABSTRACT
BACKGROUND:Superparamagnetic iron oxide nanoparticles (Fe3O4 NPs) have been widely used in MRI. It is vital to prepare the superparamagnetic MRI contrast agent with high stability, biocompatibility and tumor targeting in order to prevent the aggregation of Fe 3 O 4 NPs and realize the high-precision diagnose of tumor. OBJECTIVE:To prepare the amphiphilic superparamagnetic composite particles with tumor targeting mediated by folate receptor. METHODS:The stable amphiphilic superparamagnetic composite particles with tumor targeting function were prepared by coating the Fe3O4 NPs with a Pluronic F127-folic acid conjugate, which was synthesized via an esterification reaction between the carboxyl group of the tumor targeting molecule, folic acid and the hydroxyl group of an amphiphilic triblock copolymer, Pluronic F127. The resultant Pluronic F127-folic acid-Fe3O4 composite particles were characterized by transmission electron microscopy, Fourier transform infrared-spectra, UV-vis absorption spectra, thermal gravimetric analysis, vibrating sample magnetometer and T2-weighted imaging. WST assay was used to characterize their cytotoxicity preliminarily. RESULTS AND CONCLUSION:The Pluronic F127-folic acid conjugates were prepared via esterification reaction. Then Fe 3 O 4 NPs were wrapped with Pluronic F127-folic acid to result in the superparamagnetic composite particles with wel dispersion and biocompatibility. The size of most superparamagnetic composite particles was less than 200 nm and the size of Fe 3 O 4 core was 10-20 nm from the observation of transmission electron microscopy. The results from the Fourier transform infrared-spectra and UV-vis absorption spectroscop confirmed that folic acid molecules were modified on the surface of the superparamagnetic composite particles successful y. The mass ratio of Pluronic F127-folic acid conjugate was determined by thermal gravimetric analysis as 27.2 wt%in the resultant Pluronic F127-folic acid-Fe 3 O 4 composite particles. The saturated magnetic intensity of the superparamagnetic composite particles was 47.35 emu/g by vibrating sample magnetometer and the relaxation rate was 0.025×106 mol/s from MRI. The WST assay showed the negligible cellcytotoxicity of Pluronic F127-folic acid-Fe3O4. The superparamagnetic composite particles have potential application as the MRI contrast agents with tumor targeting, and the Pluronic F127-folic acid-Fe 3 O 4 composite particles is expected to be used as a MRI contrast agent for tumor targeting.