Europium-Coordinated Gold Nanoparticles on Paper for the Colorimetric Detection of Arsenic(III, V) in Aqueous Solution

The europium-functionalized gold nanoparticle is developed as a sensor for highly sensitive and specific detection of the very low concentration of AsIII and AsV ions in water and using the paper strip. The GNP-MMT@Eu nanosensor is synthesized by stepwise chemical conjugations of gold nanoparticle (GNP) with 2-mercapto-4-methyl-5-thiazoleacetic acid (MMT) followed by europium chloride (EuCl3) in deionized (DI) water. GNP-MMT@Eu shows a visible color change in the presence of both AsIII and AsV ions in an aqueous medium, because of arsenic-mediated aggregation through electrostatic attraction and covalent-type interaction that form an inner-sphere arsenic complex between nanoparticles, which is proportional to the concentration of arsenic. The fluorometric properties of the nanosensor are not significant, and thus, only colorimetric and spectroscopic methods that are very much selective for AsIII and AsV ions are used with a detection limit of ≤10.0 ppb. GNP-MMT@Eu also shows excellent capabilities for regeneration and quantitative estimation of total dissolved arsenic in a real water sample, signifying the usefulness of the developed nanosensor for field-test applications such as arsenic level screening during the water quality monitoring process.