Functionalized magnetic core–shell Fe3O4@SiO2 nanoparticles as selectivity-enhanced chemosensor for Hg(II)

A colorimetric and ‘‘turn-on” fluorescent chemosensor Rho-Fe3O4@SiO2 for Hg2+ in which N-(rhodamine-6G)lactam-ethylenediamine (Rho-en) is conjugated with the magnetic core–shell Fe3O4@SiO2 NPs has been strategically designed and synthesized. The final product was characterized by X-ray power diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectra (FTIR) and UV–visible absorption and fluorescence emission. Fluorescence and UV–visible spectra results showed that the resultant multifunctional nanoparticles Rho-Fe3O4@SiO2 exhibited selective ‘turn-on’ type fluorescent enhancements and distinct color changes with Hg2+. The selectivity of the Rho-Fe3O4@SiO2 for Hg(II) ion is better than that of the Rho-en in the same conditions. In addition, the presence of magnetic Fe3O4 nanoparticles in the sensor Rho-Fe3O4@SiO2 NPs would also facilitate the magnetic separation of the Hg(II)–Rho-Fe3O4@SiO2 from the solution.

► The Rho-Fe3O4@SiO2 shows excellent selective Hg(II) sensing over other cations and can be considered as a colorimetric and “turn-on” fluorescent chemosensor.
► The selectivity of the Rho-Fe3O4@SiO2 for Hg(II) is better than that of the Rho-en in the same conditions.
► The presence of magnetic Fe3O4 nanoparticles in the sensor facilitate the magnetic separation of the Hg(II)–Rho-Fe3O4@SiO2 from the solution.
► This work provides a platform to prepare magnetic nanoparticles modified by organic chemosensors with high affinity, selectivity and sensitivity to detect metal ions.