Multiplex plasmonic sensor for detection of different metal ions based on a single type of gold nanorod

In this paper, a label-free multiplex plasmonic sensor has been developed to selectively determine different metal ions including Fe(3+), Hg(2+), Cu(2+), and Ag(+) ions based on a single type of gold nanorod (GNR). Under proper conditions, these metal ions can react with GNRs, resulting in changes of nanostructure and composition. The determination of Fe(3+), Hg(2+), Cu(2+), and Ag(+) ions is therefore readily implemented due to changes of longitudinal plasmon wavelength (LPW) of nanorods. Moreover, the GNR-based assay can not only determine all four kinds of metal ions successively but also can detect which of any one or several kinds of metal ions. This assay is sensitive to detect Fe(3+), Hg(2+), Cu(2+), and Ag(+) as low as 10(-6), 10(-8), 10(-10), and 10(-8) M, respectively. Importantly, the special nanostructure and composition of the nanorods are induced by these metal ions, which allow this sensor to maintain high selectivity to determine these metal ions. This nanosensor abrogates the need for complicated chemosensors or sophisticated equipment, providing a simple and highly selective detection platform.