Synthesis of Starch-Stabilized Ag Nanoparticles and Hg(2+)Recognition in Aqueous Media

The starch-stabilized Ag nanoparticles were successfully synthesized via a reduction approach and characterized with SPR UV/Vis spectroscopy, TEM, and HRTEM. By utilizing the redox reaction between Ag nanoparticles and Hg(2+), and the resulted decrease in UV/Vis signal, we develop a colorimetric method for detection of Hg(2+)ion. A linear relationship stands between the absorbance intensity of the Ag nanoparticles and the concentration of Hg(2+)ion over the range from 10 ppb to 1 ppm at the absorption of 390 nm. The detection limit for Hg(2+)ions in homogeneous aqueous solutions is estimated to be ~5 ppb. This system shows excellent selectivity for Hg(2+)over other metal ions including Na(+), K(+), Ba(2+), Mg(2+), Ca(2+), Fe(3+), and Cd(2+). The results shown herein have potential implications in the development of new colorimetric sensors for easy and selective detection and monitoring of mercuric ions in aqueous solutions.