Ratiometric fluorescent sensing of mercury (II) ion based on the Pt nanozyme-triggered fluorescence resonance energy transfer between Si quantum dots and 2,3-diaminophenazine

The demand for efficient methods to determine mercury ion (Hg 2+ ) is increasing. Herein, we developed a ratiometric fluorescence assay by the coupling of nanozyme and fluorescence resonance energy transfer (FRET) to determine Hg 2+ . Platinum nanoparticles (PtNPs) was synthesized as effective nanozyme to catalyze the oxidation of o-phenylenediamine (OPD) at the presence of hydrogen peroxide (H 2 O 2 ) to produce 2,3-diaminophenazine (DAP). The fluorescence emission of Si quantum dots (QDs) at 414 nm (I 414 ) was observed to be quenched by DAP (emission at 576 nm (I 576 )) via FRET mechanism, whereas Hg 2+ can depress the catalytic activity of PtNPs to generate DAP. Based on this principle, SiQDs/PtNPs/OPD/H 2 O 2 -based ratiometric fluorescence assay was developed that the emission ratio of DAP and SiQDs (I 576 /I 414 ) decreased with a higher concentration of Hg 2+ . Noteworthy, the sensitivity of such system was found to be related with the value of I 576 /I 414 . The developed assay offered a detection range of 20–3000 nM and a detection limit of 10.5 nM. This assay was applied to analyze Yangtze river water, and its reliability has been validated by the standard ICP-MS method. Our work provided an effective and convenient method for Hg 2+ detection.