Preparation of Biocompatible, Luminescent-Plasmonic Core/Shell Nanomaterials Based on Lanthanide and Gold Nanoparticles Exhibiting SERS Effects

Multifunctional core/shell type nanomaterials composed of nanocrystalline, lanthanide doped fluorides and gold nanoparticles (Au NPs) were successfully prepared. The products were synthesized to combine luminescence properties of the core NPs, i.e., LnF(3)/SiO2 NH2 and KLn(3)FiO/SiO2 NH2, and plasmonic activity of the shell Au NPs within a single nanomaterial. The luminescent lanthanide NPs (10 or 150-200 nm) were separated from the gold NPs (6-30 nm) using an amine modified silica shell (thickness approximate to 30 nm). The synthesized products exhibited bright green (Tb3+) and red (Eu3+) emission under UV light irradiation. Surface modification with Au NPs influenced the product emission and luminescence decay characteristics. The luminescent-plasmonic nanomaterials were used as platforms for surface enhanced Raman scattering (SERS) measurements. 4-Mercaptobenzoic acid, choline, and T4 bacteriophages were utilized as SERS probes. For all synthesized nanomaterials, the SERS spectra for all probes studied exhibited higher intensity in comparison with the spectra measured using a commercial SERS substrate. Cytotoxicity of the products was evaluated in fibroblast cells. The results obtained showed biocompatibility of the synthesized nanomaterials in a dose-dependent manner.