| In recent years, fluorescent probes, because of their simplicity, high selectivity and sensitivity in fluorescent assays, have been widely used to detect all kinds of anions, cations and biomolecules. However, in practice, many organic fluorescent dye molecules are poorly water-soluble, high toxicity, and hardly separated from a solution. To solve the problems above, molecular fluorescent probes were grafted to the surface of multifunctional silica nanoparticles to form the novel organic-inorganic hybrid fluorescent nanoprobes.Firstly,1,8-naphthalimide group modified multifunctional silica nanoparticles having high magnetization have been successfully prepared to form the NAU-Fe3O4@SiO2hybrid nanomaterials. These multifunctional nanoparticles were characterized by Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), Elementary analysis, X-ray powder diffraction (XRD) and Vibrating sample magnetometer (VSM). The characterizations data indicated that the organic ligand was successfully grafted on the surface of the magnetic silica nanoparticles. The fluorescent changes of the hybrid material upon the addition of cations (H+, F" and their mixtrue) is utilized as an INH logic gate at the molecular level, using the fluorescence intensity signal as output.Secondly, we developed a molecular logic gate system (NTPA-Fe3O4@SiO2) based on the multifunctional magnetic silica nanoparticles. These multifunctional nanoparticles were characterized by FT-IR, TEM, Elementary analysis, XRD, VSM, thermal gravimetric analysis (TGA), UV-visible absorption and fluorescence measurement. UV-visible absorption and fluorescence spectra revealed that NTPA-Fe3O4@SiO2displayed high selectivity for Cu2+, and the complexation of Cu2+with NTPA-Fe3O4@SiO2(Cu-NTPA-Fe3O4@SiO2) exhibited selective recognition towards PPi. Moreover, the fluorescence emission changes of NTPA-Fe3O4@SiO2by the inputs of Cu2+and PPi can be viewed as an IMPLICATION logic gate at the nanoscale level.Thirdly, a highly sensitive method for recognition Zn2+and hydrogen sulfide (H2S) has been developed by using a novel fluorescent probe based on quinoline modified multifunctional magnetic silica nanoparticles (R1). The chemoprobe R1shows excellent fluorescence sensitivity and selectivity toward Zn2+and H2S in aqueous media, and displays off-on-off type fluorescence change with alternately added Zn2+and H2S to the media along with reversible forming-separating of the complex. Furthermore, the magnetic nanocomposites can be easily separated from solutions by adding an external magnetic field. Finally, using Zn2+and H2S as inputs and the fluorescence intensity as output, an INHIBIT logic gate can be construct at the nanoscale level.Finally, a novel dansyl group functionalized Fe3O4@SiO2magnetic nanomaterial with a core-shell structure was developed, aiming to detect and remove of Hg2+from aqueous media. The multifunctional nanocomposite shows excellent fluorescence sensitivity and selectivity towards Hg2+over other metal ions (Na+, K+, Mg2+, Al3+, Ca2+,Cd2+, Ni2+, Co2+, Fe3+, Zn2+, Pb2+, Cu2+, Ag+).Concentrations as low as10-8M can be detected and the addition of other metal ions has a negligible influence on the fluorescence emission. Regarding the reversibility of the nanosized probe, the fluorescence of the DAP-Fe3O4@SiO2nanocomposite in the presence of Hg2+ion is found to be almost reversible when treated with iodide anion. And the nanocomposite can be easily separated from solutions by adding an external magnetic field. Moreover, the functionalized nanosphere shows a good adsorption capacity to Hg2+, which makes it repeatedly applicable for simultaneous Hg2+sensing and removal from polluted water. These results indicate that the multifunctional nanocomposite may find potential application for simple detection and easy removal of Hg2+in biological and environmental areas. |
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