Arsenazo III-functionalized gold nanoparticles for photometric determination of uranyl ion

Gold nanoparticles (AuNPs) were functionalized with the indicator dye Arsenazo III via reductive synthesis of AuNPs in the presence of arsenazo III. The indicator dye is shown to be immobilized on the AuNPs via interaction between gold and sulfo groups. The functionalized AuNPs undergo aggregation in the presence of uranyl ion due to the coordination interaction between arsenazo III and uranyl ion. This is accompanied by a longwave shift of the surface plasmon resonance absorption band (from 535 nm to 548 nm) and an up to 46.8 % increase in absorbance. This finding forms the basis for a photometric assay for uranyl ion. It shows good selectivity and has a 0.5 μM detection limit. Applied to the determination of uranyl ion in spiked environmental water samples, the recoveries were between 97 and 106 %. Arsenazo III dye functionalized gold nanoparticles (AuNPs) were prepared via a one-pot reduction reaction. Based on the coordination interaction of arsenazo III functionalized AuNPs and uranyl ion, an assay for uranyl ion was developed.