A novel ratiometric fluorescence probe for the detection of copper (II) and silver(I) based on assembling dye-doped silica core–shell nanoparticles with gold nanoclusters

A creatively designed and constructed a multifunctional ratiometric fluorescence probe is reported by assembling glutathione (GSH)-protected gold nanoclusters (AuNCs) with fluorescein-doped mesoporous silica nanoparticle (FS) for the detection of Cu²⁺ and Ag⁺ ions, which could eliminate most interferences by self-calibration. Under the excitation at 450 nm, the fluorescence connected with AuNCs can rapidly respond by quenching or enhancement, respectively, for Cu²⁺ and Ag⁺ ions, while the fluorescein isothiocyante (FITC) fluorescence served as reference with negligible change. The fluorescence intensity ratio showed good linear relationships with Cu²⁺ and Ag⁺ concentrations in the range 0.5–10 μM and 0.1–8 μM, respectively. The detection limits were as low as 140 nM and 60 nM for Cu²⁺ and Ag⁺ ions, respectively. The color change induced by fluorescent intensity ratio variation could also be employed for visual discrimination. The AuNC-embedded FS (FS-Au) nanoprobe was successfully used for Cu²⁺ and Ag⁺ ion determination in drinking water and intracellular Cu²⁺ imaging, which exhibits promising prospects in cost-effective and rapid determination of both Cu²⁺ and Ag⁺ with good sensitivity and selectivity. Graphical