Hairpin oligonucleotides anchored terbium ion: a fluorescent probe to specifically detect lead(ii) at sub-nM levels

Abstract

A terbium based fluorescent probe was synthesized by coordinating terbium ions with a designed oligonucleotides (5'-ATATGGGGGATAT-3', termed GH5). GH5 improved the fluorescence of terbium ions by four orders of magnitude. The fluorescence enhancement of terbium ions by different oligonucleotides sequences indicated that the polyguanine loop of the hairpin GH5 is key to enhance terbium ion emission. The quantum yield of Tb-GH5 probe was 10.5% and the probe was photo-stable. The result of conductivity titration indicated that the stoichiometry of the probe is 3.5 Tb: 1 GH5, which is confirmed by fluorescence titration. This probe had high sensitivity and specificity for the detection of lead ions. The fluorescence intensity of this probe was linear with respect to lead concentration over a range 0.3-2.1 nM (R(2) = 0.99). The limit of detection for lead ions was 0.1 nM at a signal-to-noise ratio of 3.

Identifying the Stoichiometry of Metal/Ligand Complex by Coupling Spectroscopy and Modelling: a Comprehensive Study on Two Fluorescent Molecules Specific to Lead

“…This trace metal can accumulate in water and soil organisms and influence the global balances and food chains [4]. Taken up from food, air or drinking water, lead causes inhibition of brain development, kidney and physical growth impairments [5], [6].…”