Silver-decorated amino-modified Fe3O4@SiO2@mTiO2 core-shell nanocomposites with catalytic and antimicrobial bifunctional activity

Integrating metal nanocomposites into a matrix is a promising approach for improving the material chemical and physical properties. Herein, Fe3O4 @SiO2 @mTiO2-NH2 @Ag (FSTN-Ag) nanocomposites were synthesized by reducing silver nitrate onto amino-modified double core-shell Fe3O4 @SiO2 @mTiO2-NH2 (FSTN) nanospheres. TEM, XRD, XPS, BET, TOC, UV–vis and FTIR spectrum were used to characterize the nanocomposites. The magnetic FSTN-Ag nanocomposites possessed a core–shell structure, with a specific surface area of 113.6 m2/g, pore volume of 0.122 cm3/g, magnetization saturation of 46.17 emu/g, and Ag mean diameter of 2.8 nm. The FSTN-Ag demonstrated high catalytic activity on reducing methyl orange (MO) and its catalytic ability could kept 85% after 5 cycles. The FSTN-Ag also effectively inhibited S. aureus and E. coli in 20 min by up to 99% or 100%, respectively. It was speculated that the antimicrobial mechanism involved the interaction of Ag+ derived from FSTN-Ag with functional groups of vital enzymes and proteins as well as strong oxidation of reactive oxygen species resulting in bacterial death. In view of the magnetic separation, biocompatibility and recyclability, the FSTN-Ag is expected to become a potential multifunctional material for biomedical and environmental remediation.