Département de chimie moléculaire

Multilayers of poly(diallyldimethylammonium chloride) (PDDA) and citrate capped Au nanoparticles (AuNPs) anchored on sodium 3-mercapto-1-propanesulfonate modified gold electrode by electrostatic layer-by-layer assembly (LbL) technique are shown to be an excellent architecture for the direct electrochem. oxidn. of As(III) species. The growth of successive layers in the proposed LbL architecture is followed by at. force microscopy, UV-vis spectroscopy, quartz crystal microbalance with energy dissipation, and electrochem. The first bilayer is found to show rather different physico-chem. characteristics as compared to the subsequent bilayers, and this is attributed to the difference in the adsorption environments. The anal. utility of the architecture with five bilayers is exploited for arsenic sensing via the direct electrocatalytic oxidn. of As(III), and the detection limit is found to be well below the WHO guidelines of 10 ppb. When the non-redox active PDDA is replaced by the redox-active Os(2,2'-bipyridine)2Cl-poly(4-vinylpyridine) polyelectrolyte (PVPOs) in the LbL assembly, the performance is found to be inferior, demonstrating that the redox activity of the polyelectrolyte is futile as far as the direct electro-oxidn. of As(III) is concerned. [on SciFinder(R)]