The aim of this master thesis is synthesis of SiO2/Au core/shell nanoparticles. These nanoparticles should improve the signal of optical coherence tomography (OCT). The procedure of nanoparticle synthesis is described in the work. Synthetized nanoparticles were analyzed by scanning electron microscopy (SEM), Ultraviolet-Visible spectroscopy (UV-Vis), Near-infrared spectroscopy (NIRS), Fourier transform-infrared spectroscopy (FT-IR) and Dynamic light scattering (DLS). Then, the synthetized nanoparticles were tested for enhancement of OCT signal. For this testing were also used commercial nanoparticles with the same structure and similar size.