Functionalized magnetic core–shell Fe3O4@SiO2 nanoparticles for sensitive detection and removal of Hg2+

Abstract

The Fe3O4 nanoparticles [NPs] coated with silica nanoparticles were designed and prepared, the obtained Fe3O4@SiO2 NPs have uniform spherical morphology with a mean diameter of about 22 nm. The inert silica coating on the surface of Fe3O4 NPs not only significantly prevented their aggregation in solution but also improved their chemical stability and provided wider sites for surface modification with organic chemosensors. Subsequently an attempt had been made that the as-synthesized Fe3O4@SiO2 NPs were modified by N-(rhodamine-6G) lactam–ethylenediamine, the functionalized magnetic Fe3O4@SiO2 NPs (Fe3O4@SiO2-Rho) served as a “naked eye” fluorescent sensor to detect Hg2+. The Fe3O4@SiO2-Rho NPs exhibited selective “turn-on” type fluorescent change from colorless to orange when adding to Hg2+. In addition, the adsorption experiments revealed that the Fe3O4@SiO2-Rho NPs had effective removal toward Hg2+. Moreover, the functionalized Fe3O4@SiO2 microspheres displayed superparamagnetic properties, which made it easier to separate the nanocomposites from the liquid phase by adding an external magnetic field. Our efforts provided a potential magnetic nanomaterial for sensitive detection and removal toward Hg2+ simultaneously. A rhodamine 6G derivative functionalized Fe3O4@SiO2 nanoparticles were designed and synthesized (as Fe3O4@SiO2-Rho). The Fe3O4@SiO2-Rho exhibited selective “turn-on” type fluorescent change from colorless to orange with Hg2+, which constituted an Hg2+-selective fluorescent colorimetric nanosensor.