Ion-directed assembly of gold nanorods: A strategy for mercury detection

Tiziana Placido, Gemma Aragay, Josefina Pons, Roberto Comparelli, M. Lucia Curri, Arben Merkoçi

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53 Citations (Scopus)


Water-soluble gold nanorods (Au NRs) have been functionalized with an N-alkylaminopyrazole ligand, 1-[2-(octylamino)ethyl]-3,5-diphenylpyrazole (PyL), that has been demonstrated able to coordinate heavy metal ions. The N-alkylaminopyrazole functionalized Au NRs have been characterized by electron microscopy and spectroscopic investigation and tested in optical detection experiments of different ions, namely, Zn2+, Cd2+, Hg 2+, Cu2+, Pb2+, and As3+. In particular, the exposure of the functionalized NRs to increasing amounts of Hg2+ ions has resulted in a gradual red-shift and broadening of the longitudinal plasmon band, up to 900 nm. Interestingly, a significantly different response has been recorded for the other tested ions. In fact, no significant shift in the longitudinal plasmon band has been observed for any of them, while a nearly linear reduction in the plasmon band intensity versus ion concentration in solution has been detected. The very high sensitivity for Hg2+ with respect to other investigated ions, with a limit of detection of 3 ppt, demonstrates that the functionalization of Au NRs with PyL is a very effective method to be implemented in a reliable colorimetric sensing device, able to push further down the detection limit achieved by applying similar strategies to spherical Au NPs. © 2013 American Chemical Society.
Original languageEnglish
Pages (from-to)1084-1092
JournalACS Applied Materials and Interfaces
Issue number3
Publication statusPublished - 13 Feb 2013


  • assembly
  • functionalization
  • gold nanorods
  • mercury
  • sensing


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