Unraveling the nature of Turkevich gold nanoparticles: the unexpected role of the dicarboxyketone species

By monitoring the synthesis of the Turkevich gold nanoparticles, under appropriate conditions, it was possible to probe the formation of the dicarboxyketone intermediate species, revealing their unexpected strong interaction with the gold nanoparticles. The dicarboxyketone species exhibited a contrasting spectral and kinetics behaviour in relation to citrate stabilized products, explaining several existing controversial points, such as the lack of reproducibility and variable SERS response. In these species, because of the covalent interaction, the chemical mechanisms involved in SERS predominate over the electromagnetic contribution observed for the citrate stabilized gold nanoparticles. New interesting aspects were found, such as a greater stabilization and strong SERS response observed even for the non-aggregated nanoparticles.