Spectroscopic evaluation of 4-(dimethylamino)pyridine versus citrate as stabilizing ligand for gold nanoparticles

A comparative study has been made on the synthetic strategy, particle morphology and surface charge of the aqueous dispersion gold nanoparticles stabilized electrostatically by 4-(dimethylamino)pyridine (DMAP) and trisodium citrate. The information from UV–vis spectroscopy, transmission electron microscopy and zeta potential measurements substantiated the result. To explore the real-time applications of these two interesting systems, solubility and stability of these two types of stabilized particles and the nature and extent of the interaction of the stabilizing ligand shell with the surface of gold nanoparticles have been elucidated. The size regime dependence of the citrate-stabilized particles has been rationalized in view of the dependence of surface area on the size of the particles.