One-step synthesis of star-like gold nanoparticles for surface enhanced Raman spectroscopy

In this paper we present a new protocol for the synthesis of Star-Like Gold Nanoparticles (SGNs) by a simple one-step, room temperature procedure not involving the use of seeds or surfactants, that can be performed in seconds in any laboratory without the need of special technologies. These particles exhibited excellent properties for Surface Enhanced Raman Spectroscopy (SERS) and, when compared with spherical nanoparticles with similar size and concentration, showed enhancing factors from 10 to 50 times higher depending on the dye and on the wavelength employed. SGNs could be used directly in suspension as single, non-aggregating particles and were shown to be active in a remarkably broad range of the light spectrum from green to near infrared. Moreover, SGNs were adsorbed on the surface of a silicon slide to prepare SERS active solid substrate. Despite the fact that the surface of the solid substrate was not perfectly homogeneous, the signals recorded from different positions acquired through DuoScan averaging mode show excellent reproducibility, demonstrating how this simple and cheap protocol can be applied in order to generate reliable and homogeneous SERS substrates.