Preparation And Surface Properties Of USPIO In Dextran

Magnetic resonance imaging (MRI) is a powerful clinical diagnostic modality for the detection and diagnosis of a wide variety of diseases, such as cancers, infarcted artery and hepatic diseases, etc. MRI contrast agent is a diagnostic agent that could be administered to a patient in order to shorten the longitudinal relaxation times, T1 and the transverse relaxation times, T2, of protons in tissues in which the agent accumulates, enhancing the image contrast between normal and diseased tissue and indicating the status of organ function or blood flow. Nowadays molecular design of nonionic, tissue-specific and macromolecular contrast agents are the research trend for the development of MRI contrast agent. Fe₃O₄ nanoparticles have been widely used in many industry fields, especially in biomedicine, such as used as a solid-phase carrier for a drug carver for cancer therapy, and as a reagent for MRI. This paper described preparation, modification and characterization of Fe₃O₄, and its initial application in Magnetic resonance imaging. Their relaxivities, in vitro and in vivo properties were also evaluated. The main results and conclusions were summarized as fellows:The Fe₃O₄ surperparamagnetic nanoparticles were prepared by FeCl₂·4H₂O, KNO₃ and NH4OH in dextran. The diameter of the particles was about 5nm. The factors of controlling the processing were investigated systematically. Size, morphology, microstructure, magnetic behavior and element of the nanoparticles were characterized by TEM, XRD, XPS, and VSM. The nanoparticles' surface was modified by Dextran, which made it Contain the hydroxyl group. According to weight the appropriate ratio of the Dextran and Fe3+ is 4-7. The TEM indicated that the particles were spherical in shape and the nanoparticles were found to be less than 5nm with narrow size distribution. The FTIR spectra indicated that the iron oxide was located by polymeric matrix. The XPS spectra of the dextran-coated colloids showed that iron oxide particles were Fe₃O₄. The in vivo MR results showed that the synthesized USPIO colloid could achieve more sensitive images and could be used as a promising magnetic resonance imaging (MRI) contrast agent. All above, the results proved that oxidation was useful method in MRI contrast agents study.