Synthesis of Starch-Stabilized Ag Nanoparticles and Hg 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. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s11671-009-9387-6) contains supplementary material, which is available to authorized users.