The Optimization of the One-Pot Synthesis of Au@SiO₂ Core–Shell Nanostructures: Modification with Dansyl Group and Their Fluorescent Properties

This work describes the optimization of the one-pot synthesis of fine core–shell nanostructures based on nanogold (Au NPs) and silica (SiO2). The obtained core–shell nanomaterials were characterized by Transmission Electron Microscopy (TEM and by the method of spectroscopes such as UV–Vis Spectroscopy and Fourier Transform Infrared Spectroscopy (FT-IR). In addition, the measurement of the zeta potential and size of the obtained particles helped present a full characterization of Au@SiO2 nanostructures. The results show that the influence of reagents acting as reducers, stabilizers, or precursors of the silica shell affects the morphology of the obtained material. By controlling the effect of the added silica precursor, the thickness of the shell can be manipulated, the reducer has an effect on the shape and variety, and then the stabilizer affects their agglomeration. This work provides also a new approach for Au@SiO2 core–shell nanostructure preparation by further modification with dansyl chloride (DNS–Cl). The results show that, by tuning the silica shell thickness, the intensity of the fluorescence spectrum of Au@SiO2–(CH2)3–NH–DNS nanocomposite is about 12 times higher than that of DNS–Cl.