Colorimetric detection of mercury(II) based on 2,2'-bipyridyl induced quasi-linear aggregation of gold nanoparticles

Heavy metal mercury(II) (Hg2+) ion is a highly toxic pollution widely distributed in air, water and soil. Simple and reliable on-site detection of Hg2+ has raised considerable concerns for environmental protection and human health but current methods necessitate sophisticated instruments and/or tedious procedures. In this work we report a simple, reliable and instrument-free colorimetric method for Hg2+ detection based on its inhibition effect on 2,2'-Bipyridyl (Bipy) induced aggregation of gold nanopartides (AuNPs). Bipy is found to be capable of triggering the quasi-linear aggregation of citrate-capped monodisperse AuNPs with a controllable manner and generate visible color change; in the presence of Hg2+ the aggregation is efficiently decelerated/inhibited, allowing naked-eye quantification of Hg2+ in a range from 0.2 to 2.0 mu M. The detection limit is further down to 38 nM when coupled to a simple UV-vis spectrometer. The method shows good selectivity toward Hg2+ and excellent reliability in various practical samples with different pH values or ionic strengths, thus holding great promise for rapid and on-site detection of Hg2+. (C) 2015 Elsevier B.V. All rights reserved.