Preparation and Characterization of Bifunctional Fluorescent Magnetic Dendrimer Microspheres

Three generations of magnetic and luminescent dendrimer microspheres were prepared. Superparamagnetic Fe3O4 nanoparticles were first prepared by hydrothermal coprecipitation of ferric and ferrous ions, followed by the modification of their surfaces with dendrimers. The surface-modified Fe3O4 nanoparticles were then linked to CdSe/CdS quantum dots (QDs), which were modified with thioglycolic acid to form the Fe3O4/CdSe/CdS fluorescent magnetic nanocomposites through the adsorption and bonding of the amino groups on the surfaces of Fe3O4 and the carboxyl groups on CdSe/CdS QDs. The structure and properties of the nanocomposites were characterized by Fourier transform infrared spectrometer(FTIR), elemental analysis(EA), transmission electron microscope (TEM), energy dispersive spectrometer(EDS), vibrating sample magnetometer (VSM), photoluminescence( PL) and UV-Vis spectrameters. The results show that the average size of three generations of nanocomposites are 15, 34 and 49 nm, respectively, the fluorescence property of G1F is the best with a fluorescent quantum yield up to 24. 1 %, while the magnetic property of G0F is the optimal with a saturation magnetization of 15. 96 A . m(2)/kg. The synthesized bifunctional nanocomposites are expected to he widely used in immune detection, luminescence detection, targeted therapy, magnetic separation and so on.