| Nowdays, functional magnetic nanoparticles (MNPs) have become one of the most popular areas in modern material science. Among these magnetic nanoparticles, Fe3O4 magnetic nanoparticles have drawn a lot of attention because of its good magnetic properties and low toxicity. To prevent magnetic nanoparticles from aggregation and give it more functional advantages, modified magnetic nanoparticles were widely researched. The modified magnetic nanoparticles have the character of superparamagnetism, good biocompability and well water-dispersibility which provide many exciting opportunities in biomedical applications.In this study, the size-uniform 5 nm, nearly spherical, and well-dispersed aqueous Fe3O4 magnetic nanoparticles with polymethacrylic acid (PMA) of different molecular were prepared by an improved chemical coprecipitation method. The relationship between the molecular weight of the PMA and stability and dissolution of Fe3O4 magnetic nanoparticles was also evaluated. Then, the functionalized Fe3O4 reacted with 4-amino-2,2,6,6-tetramethyl-piperidine-oxyl (4-NH2-TEMPO) to give the spin labeling magnetic nanoparticles. The multifunctional MNPs was characterized by X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FT-IR),Vibrating sample magnetometer(VSM),Dynamic light scattering (DLS),Electron paramagentic resonance(EPR),Transmission electron microscope(TEM). Finally, cytotoxicity texts and animal body distribution tests were also carried out, to study the feasibility of EPR bioprobe. |
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