The Ag@Polyaniline (PANI) core-shell nanoparticles were successfully synthesized by one-step radiation of sunlight method using silver nitrate as the oxidant for aniline without any additives or templates. The Ag@PANI core-shell nanocomposites were used as active surface enhanced Raman scattering (SERS) nanoprobes for the detection of some heavy metal ions, such as Pb2+, Cu2+ Hg2+, Cd2+, and so on, which is based upon the Raman intensity response of PANI to metal ions. It turns out that the nanoprobes represent a rather high selectivity for Hg2+ detection. It is also important that the detection limit of Hg2+ concentration is ca. 1 x 10(-12) M in this system, due to the great sensitivity of SERS nanoprobes. The developed nanoprobes could have potential applications in highly sensitive chemical, environmental and biological analysis, as well as medical detection. Crown Copyright (C) 2013 Published by Elsevier B.V. All rights reserved.