Luminescent gold nanoparticles as dual-modality sensors for selective copper (II) ion detection

Ion sensors are important tools for the determination of metal ion concentrations in aqueous environments. Here we describe the synthesis of ca. 3 nm cysteamine and glutathione-coated luminescent gold nanoparticles (CG-AuNPs) using a one-pot mild reduction method; resulting nanoparticles were extensively characterized. Fluorescence spectroscopy and dynamic light scattering (DLS) measurements indicate the synthesized gold nanoparticles exhibit excellent stability at physiological pH and high ionic strength. We demonstrate that these nanoparticles can act as highly sensitive and selective dual-modality sensors of Cu2+ ions under physiologically-relevant conditions. Limits of detection were determined to be 18.2 nM (fluorescence) and 19.6 nM (DLS), respectively.