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Abstract: We synthesized Fe3O4@C@Ag nanocomposites through a combination of solvothermal, hydrothermal, and chemical redox reactions. Characterization of the resulting samples by X-ray diffraction, Fourier-transform infrared spectroscopy, field-emission scanning and transmission electron microscopy, and magnetic measurement is reported. Compared to Fe3O4@Ag nanocomposites, the Fe3O4@C@Ag nanocomposites showed enhanced antibacterial activity. The Fe3O4@C@Ag nanocomposites were able to almost entirely prevent growth of Escherichia coli when the concentration of Ag nanoparticles was 10μg/mL. Antibacterial activity of the Fe3O4@C@Ag nanocomposites was maintained for more than 40h at 37°C. The intermediate carbon layer not only protects magnetic core, but also improves the dispersion and antibacterial activity of the silver nanoparticles. The magnetic core can be used to control the specific location of the antibacterial agent (via external magnetic field) and to recycle the residual silver nanoparticles. The Fe3O4@C@Ag nanocomposites will have potential uses in many fields as catalysts, absorbents, and bifunctional magnetic–optical materials. [Copyright &y& Elsevier]

Abstract: In this study, we synthesized γ-Fe2O3@SiO2@TiO2–Ag nanocomposites with a core–shell structure using a hydrothermal method and a sol–gel method. Transmission electron microscope images showed that the γ-Fe2O3@SiO2@TiO2–Ag nanocomposites had a core–shell structure. Photocatalytic examination of the γ-Fe2O3@SiO2@TiO2–Ag was carried out using methyl orange solution under UV irradiation. The γ-Fe2O3@SiO2@TiO2–Ag nanocomposites showed stronger photocatalytic activity than pure TiO2. With γ-Fe2O3@SiO2@TiO2–Ag, about 84% of the methyl orange was decomposed after 1h of UV irradiation, versus 49% for pure TiO2. The antibacterial activity of γ-Fe2O3@SiO2@TiO2–Ag nanocomposites was remarkably greater than that of bare TiO2 nanoparticles. The introduction of silver nanoparticles into the TiO2 matrix facilitates charge separation by trapping photo-generated electrons, thereby enhancing biological activity and photoactivity. [Copyright &y& Elsevier]