A Highly Robust Recyclable Displacement Assay for Mercuric Ions in Aqueous Solutions and Living Cells

摘要

We designed a recyclable Hg²⁺ probe based on Rhodamine B isothiocyanate (RBITC) - poly (ethylene glycol) (PEG)-co-modified gold nanoparticles (AuNPs) with excellent robustness, selectivity and sensitivity. Based on a rational design, only Hg²⁺ can displace RBITC from the AuNP surfaces, resulting in a remarkable enhancement of RBITC fluorescence initially quenched by AuNPs. To maintain stability and monodispersity of AuNPs in real samples, thiol-terminated PEG was employed to bind with the remaining active sites of AuNPs. Besides, this displacement assay can be regenerated by resupplying free RBITC into the AuNPs solutions that were already used for detecting Hg²⁺. Importantly, the detection limit of this assay for Hg²⁺ (2.3 nM) was lower than the maximum limits guided by the United States Environmental Protection Agency as well as that permitted by the World Health Organization. The efficiency of this probe was demonstrated in monitoring Hg²⁺ in complex samples such as river water and living cells.