Preparation And Characterization Of Fe₃O₄@SiO₂-Znse@zns Magnetic Fluorescent Nanoparticles

Fe₃O₄magnetic nanoparticles （MNPs） exhibit superparamagnetic, which are often usedas the targeting materials in the biomedicine. But when they are exposed in the biologysystem, they tend to aggregation and corrosion. Coating the Fe₃O₄MNPs with SiO₂shell cansolve the problems above. Compared with the other materials, SiO₂used as shell material hasmany advantages, such as the cheap and extensive sources, simple preparation and abundantof active–OH groups. CdX quantum dots （QDs） have an excellent fluorescent property, whichare often used as tracing material, but they are toxic for body. ZnX QDs are the non-toxic andblue-emitting QDs, being taking place of the CdX QDs.Fe₃O₄@SiO₂core-shell nanoparticles （NPs） can be prepared by the stÇ'ber method assitedby both the mechanical stirring and ultrasonic dispersion. The optimum parameters are thatt=10hours, T=35℃, V（TEOS）=0.3mL, V（NH3H2O）=0.3mL, m（Fe₃O₄）=0.0200g.Fe₃O₄@SiO₂core-shell nanoparticles show a narrow size distribution, of which diameterranges from40nm to50nm. Compared with ZnSe QDs, ZnSe@ZnS QDs show higherfluorescence efficiency and stabler optical stability, which are the more proper tracingmaterials.Linking the Fe₃O₄@SiO₂core-shell nanoparticles and the ZnSe@ZnS QDs can obtainthe excellent targeting and tracing nanoparticles through the amidation reaction. The optimumparameters are that n（ZnSe@ZnS）:n（Fe₃O₄@SiO₂）=4:1, n（EDCl）:n（DMAF）=2:1, T=35℃,t=4hours. The Fe₃O₄@SiO₂-ZnSe@ZnS magnetic fluorescent nanoparticles （MFNPs） exhibitexcellent fluorescence property and supermagnetism. The average diameter of the MFNPs isabout50⁷0nm, which has a narrow size distribution.