Crystallite size increased from 2.0 to 5.5 nm for the FePt network capsules after hydrothermal treatment. Diffraction peaks from spinel-type iron oxide were observed for the FePt network capsules. Supercritical water has high oxidizability and is used to oxidize organic compounds. Therefore, either iron oxide was formed on the surface of the FePt network shell or Fe was dissolved BI 6727 out into the supercritical water and then oxidized during the hydrothermal treatment. Figure 4. X-ray diffraction patterns of FePt-nanoparticle/PDDA/silica composite particles, FePt-nanoparticle/PDDA hybrid capsules, and FePt network capsules after hydrothermal treatment. Table 1.
Crystallite size and saturation magnetization of FePt-nanoparticle/PDDA/silica composite particles, FePt-nanoparticle/PDDA hybrid capsules and FePt network capsules after hydrothermal treatment Magnetization loops of the composite particles and the two types of FePt capsules were measured at 300 K in applied magnetic fields from ?9 to 9 T, and their magnetization at 9 T is summarized in Table 1. Magnetization per weight at 9 T was increased after dissolution of the silica template particles from the composite particles due to the removal of the non-magnetic silica particles (7.6 emu/g). The magnetization at 9 T of the FePt network capsules after hydrothermal treatment was 12.4 emu/g. FePt network capsules exhibited higher magnetization than FePt-nanoparticle/PDDA hybrid capsules because the crystallite size was increased by the hydrothermal treatment.
The magnetic characterization revealed that the two types of FePt magnetic capsules exhibited superparamagnetic behavior at 300 K. This property should help to avoid the embolism of blood vessels during delivery of therapeutic agents to cancer lesions because the capsules do not have spontaneous magnetization and do not coagulate without magnetic fields.22,28 Drug Delivery Experiment Lipid-coated FePt network capsules loaded with doxorubicin (FePt-Dox) were obtained using the FePt network capsules fabricated by hydrothermal treatment of composite particles fabricated with a weight ratio of FePt precursors to silica particles of 1 (Figs. 2C and and3A).3A). Figure 5 shows an optical micrograph and fluorescence micrograph of the cells incubated with FePt-Dox. The fluorescent micrograph was observed in the same field of the optical micrograph.
Fluorescence microscopy revealed doxorubicin (Dox) was loaded into an internal space of FePt network capsules. Dox was translated through their pores AV-951 to their hollow space by diffusion, leading to the formation of FePt-Dox. We found that the cells were dyed by FePt-Dox from the morphology change of the cells capturing FePt-Dox from the comparison between Figure 5A and B. FePt network capsules without Dox were not toxic to the cells reported in our previous work.19 These results showed FePt-Dox had cellular toxicity to gastric cancer cells.