Malonamide dithiocarbamate functionalized gold nanoparticles for colorimetric sensing of Cu2+ and Hg2+ ions

Abstract

In this study, a colorimetric probe was developed based on malonamide dithiocarbamate functionalized gold nanoparticles (MA–DTC–Au NPs) for the simultaneous colorimetric detection of Cu²⁺ and Hg²⁺ ions. The MA–DTC–Au NPs quickly aggregated in the presence of Cu²⁺ and Hg²⁺ ions, resulting in a color change from red to blue and a red-shift in their surface plasmon resonance peak (SPR) from 525 to 780 nm and to 680 nm for Cu²⁺ and Hg²⁺ ions, respectively. On the basis of this, the concentration of Cu²⁺ and Hg²⁺ ions can be visualized with the naked eye and can be quantitatively determined by UV-visible spectroscopy. The absorption ratios A_{780 nm}/A_{525 nm} and A_{680 nm}/A_{525 nm} show linear relationships with Cu²⁺ and Hg²⁺ ion concentrations within concentration ranges from 0.01 to 5 and 0.01 to 10 μM. The detection limits are as low as 41 nM and 45 nM for Cu²⁺ and Hg²⁺ ions, respectively. The MA–DTC–Au NPs were used as a potential colorimetric probe for the rapid, selective and sensitive detection of Cu²⁺ and Hg²⁺ ions in environmental water samples (drinking, tap, canal and river water).