A novel fluorescent “off-on” sensor for selective detection of mercury based on perylene dye and gold nanoparticles

A novel fluorescence "off-on" strategy based on a perylene probe (PDI) and arginine functionalized gold nanoparticles (arg-AuNPs) for the sensing of mercury ions (Hg2+) has been developed. Due to the strong electrostatic and hydrophobic interactions as well as the strong π-π stacking effect, the PDI probe can be adsorbed onto the surface of the nanoparticles, inducing the aggregation of arg-AuNPs. Consequently, the fluorescence peaks of PDI at 550 and 591 nm were quenched by arg-AuNPs through an energy transfer (ET) process, which could be enhanced upon the addition of Hg2+. The presence of Hg2+ could prevent the ET process, thus recovering the fluorescence of PDI. An "off-on" fluorescence signal was therefore detected. Our assay method shows very high sensitivity with a limit of detection of 0.6 nM, and remarkable selectivity against common interfering metal ions. This sensing method has also been successfully used for real sample analysis. The "off-on" fluorescence sensing method is fairly simple, fast, and inexpensive, and the fluorescence quenching mechanism of PDI induced by arg-AuNPs is expected to be utilized for more target sensing applications.