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

Abstract The Fe 3 O 4 nanoparticles [NPs] coated with silica nanoparticles were designed and prepared, the obtained Fe 3 O 4 @SiO 2 NPs have uniform spherical morphology with a mean diameter of about 22 nm. The inert silica coating on the surface of Fe 3 O 4 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 Fe 3 O 4 @SiO 2 NPs were modified by N -(rhodamine-6G) lactam–ethylenediamine, the functionalized magnetic Fe 3 O 4 @SiO 2 NPs (Fe 3 O 4 @SiO 2 -Rho) served as a “naked eye” fluorescent sensor to detect Hg 2+ . The Fe 3 O 4 @SiO 2 -Rho NPs exhibited selective “turn-on” type fluorescent change from colorless to orange when adding to Hg 2+ . In addition, the adsorption experiments revealed that the Fe 3 O 4 @SiO 2 -Rho NPs had effective removal toward Hg 2+ . Moreover, the functionalized Fe 3 O 4 @SiO 2 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 Hg 2+ simultaneously. Graphical Abstract A rhodamine 6G derivative functionalized Fe 3 O 4 @SiO 2 nanoparticles were designed and synthesized (as Fe 3 O 4 @SiO 2 -Rho). The Fe 3 O 4 @SiO 2 -Rho exhibited selective “turn-on” type fluorescent change from colorless to orange with Hg 2+ , which constituted an Hg 2+ -selective fluorescent colorimetric nanosensor.