A highly sensitive and selective turn-on fluorogenic and colorimetric sensor based on pyrene-functionalized magnetic nanoparticles for Hg2+ detection and cell imaging

In this paper, a colorimetric and “turn-on” fluorescent sensor (Py–Si–Fe3O4@SiO2 NPs) for Hg2+ detection was designed with pyrene derivative covalently grafted onto the surface of magnetic core/shell Fe3O4@SiO2 nanoparticles using the silanol hydrolysis approach. The Py–Si–Fe3O4@SiO2 inorganic–organic hybrid material was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray power diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and fluorescence emission. The results of fluorescence spectra showed that the resultant multifunctional nanoparticles exhibited selective turn-on type fluorescence enhancement with Hg2+. In addition, the presence of magnetic Fe3O4 nanoparticles in the sensor Py–Si–Fe3O4@SiO2 NPs would also facilitate the magnetic separation of Hg2+–Py–Si–Fe3O4@SiO2 from the solution. The as-prepared chemosensor was also successfully applied to detect Hg2+ in environmental water samples and serum sample. Results from confocal laser scanning microscopy experiments demonstrated that this chemosensor was cell permeable and can be used as a fluorescent probe for monitoring Hg2+ in living cells.