A novel fluorescence “off-on” sensor for the 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.