Simultaneous sensitive detection of lead(Ⅱ), mercury(Ⅱ) and silver ions using a new nucleic acid-based fluorescence sensor

Abstract

A new nucleic acid-based fluorescence sensor is reported for simultaneous detection of Pb²⁺, Ag⁺, and Hg²⁺ based on the specific catalytic activity of Pb²⁺ for a particular DNAzyme, specific regulation of Ag⁺ on “C-Ag⁺-C” complex, and stable complex formed by Hg²⁺ and rhodamine B isothiocyanate (RBITC). Three fluorescence dyes, aminomethylcoumarin acetic acid (AMCA), 5-carboxyfluorescein (FAM), and RBITC, were modified on the probes and served as fluorescent donors. Upon DNA interaction with these metal ions and AuNP fluorescence quenching effect on the fluorescence dyes,the fluorescencerecovery of RBITC and the fluorescencequenching of AMCA and FAM were monitored to detect Hg²⁺, Pb²⁺, and Ag⁺, separately, without the need of using any masking reagents. This sensor exhibited high sensitivity and selectivity. The limit of detection (LOD) is 0.48 nM for Pb²⁺, 0.23 nM for Ag⁺, and 0.17 nM for Hg²⁺. Finally, this sensor was successfully applied for simultaneous detection of Pb²⁺, Ag⁺, and Hg²⁺ in real sample.