A portable ratiometric fluorescent strip for sensitive determination of mercuric ions

In this work, a portable and simple dual-emissive ratiometric fluorescent strip has been built up for the rapid and accurate detection of mercuric ions (Hg2+). Dual-emissive ratiometric fluorescent probes are assembled by using red colored bovine serum albumin (BSA)-Au nanocluster (NCs) as detection probes and blue colored l-cysteine (Cys)-Au NCs as internal standard probes. Hg2+ induces the fluorescence quenching of BSA-Au NCs but almost has no obvious effects on the fluorescent signals of Cys-Au NCs. The assembled ratiometric fluorescent probes achieve sensitive and accurate detection of Hg2+ in the range from 50 nM to 1 μM, and the limit of detection (LOD) is as low as 9 nM. The obvious color variations from red to blue enable the visual detection of Hg2+ at optimized pH by naked eyes. Dual-emissive ratiometric fluorescent strip is established and applied for the fluorescence colorimetric detection of Hg2+, which provides a platform for the rapid real-time on-site heavy metal ions detection.