Synthesis of novel nanodiamonds–gold core shell nanoparticles

•Si vacancies defected nano-diamonds (ND) were utilized for their intense optical emission at 738 nm in the visible red region;•The SiV nanodiamond surfaces were functionalized and a gold shell was deposited on the SiV nanodiamonds (ND@Au).•The ND@Au were characterized by SEM, UV–Vis, Raman spectroscopies•When excited with green laser, the silicon doped nanodiamonds emit a stable fluorescence peaked at 740 nm with no photobleaching and photoblinking.•In this work we demonstrate that optical properties of the SiV nanodiamonds are retained after the formation of the gold shell leading to novel, biocompatible and photostable nanoprobes in which fluorescence is coupled to plasmonic properties enabling SERS.

This work presents novel diamond-based nanostructures formed by a fluorescent nanodiamond core coated with a gold shell (ND@Au). Gold shell was grown on silicon-doped nanodiamonds in water by controlled reduction of gold chloride. The resulting gold-coated nanodiamond samples were characterized by means of scanning electron microscopy, UV–visible, Raman and luminescence spectroscopies. These gold-coated nanodiamonds showed a strong resonance absorption in the visible and near-infrared (NIR) range. When excited with green laser, the silicon doped nanodiamonds emit a stable fluorescence peaked at about 740 nm due to the SiV centers with no photobleaching and photoblinking. In this work we demonstrate that optical properties of the silicon-doped nanodiamonds are retained after the formation of the gold shell.