Preparation of a novel core-shell Ag-graphene@SiO2 nanocomposite for fluorescence enhancement.

A facile one-pot water-in-oil microemulsion method has been developed for the synthesis of a novel core-shell Ag-graphene@SiO2 nanocomposite with fluorescein isothiocyanate (FITC) doped in the shell. During the preparation process, reducing both Ag+ and graphene oxide, and loading of Ag nanoparticles on graphene were occurred in the microemulsion simultaneously. Then FITC was covalently doped in the silica shell through a copolymerization reaction with tetraethoxysilane (TEOS). The morphology and optical properties of the nanocomposite were characterized by transmission electron microscope (TEM), UV-Vis spectrum, fluorescence emission spectrum and FT-IR spectrum, respectively. The results showed that the emission intensity from the as-prepared nanocomposite was 3-fold higher than that of control silica nanoparticles in which graphene was absent. The graphene in the as-prepared nanocomposite exhibited an enhanced effect for the metal enhanced fluorescence (MEF). This enhancement offers a potential increase in overall nanoprobe detectability. This work could provide new insights into fabrication of Ag-graphene based nanocomposites and facilitate their application.