Tyrosine capped silver nanoparticles: A new fluorescent sensor for the quantitative determination of copper(II) and cobalt(II) ions

Nanoparticles have been increasingly used as sensors for several organic and inorganic analytes. In this work, we report a study on the synthesis of novel highly fluorescent L-Tyr capped silver nanoparticles (AgNPs) and their use for the determination of metal ions. The AgNPs have been characterized by TEM, UV-Vis and Photoluminescence (PL) spectroscopy and dynamic light scattering (DLS) measurements and used for the quantitative determination of Co(II) and Cu(II) ions. In the L-Tyr capped AgNPs, the a-amino and a-carboxyl groups of the surface-confined amino acid can coordinate the entitled metal ions, giving rise to a decrease of the silver surface plasmon absorption, that is linearly correlated with the metal ions concentrations. The addition of Co(II) and Cu(II) solutions to the L-Tyr AgNPs also induces a paramagnetic quenching of the fluorescence in the PL spectra and the related Stern Volmer plots highlight a linear correlation over the whole concentration range for both metal ions, with a more pronounced effect for the copper(II) ion.