Tb <sup>3+</sup>-nucleic acid probe-based label-free and rapid detection of mercury pollution in food
Xuhan Xia, Chenxi Zhou, Yulin Zhu, Dong Yi, Qiang He, Mohammad Rizwan Khan, Yuanlong Chi, Rosa Busquets, Ruijie Deng, Yao Ren
Abstract
Mercury is a threatening pollutant in food, herein, we developed a Tb<sup>3+</sup>-nucleic acid probe-based label-free assay for mix-and-read, rapid detection of mercury pollution. The assay utilized the feature of light-up fluorescence of terbium ions (Tb<sup>3+</sup>) via binding with single-strand DNA. Mercury ion, Hg<sup>2+</sup> induced thymine (T)-rich DNA strand to form a double-strand structure (T-Hg<sup>2+</sup>-T), thus leading to fluorescence reduction. Based on the principle, Hg<sup>2+</sup> can be quantified based on the fluorescence of Tb<sup>3+</sup>, the limit of detection was 0.0689 μmol/L and the linear range was 0.1 - 6 μmol/L. Due to the specificity of T-Hg<sup>2+</sup>-T artificial base pair, the assay could distinguish Hg<sup>2+</sup> from other metal ions. The recovery rate was ranged in 98.71% -101.34% for detecting mercury pollution in three food samples. The assay is low-cost, separation-free and mix-to-read, thus was a competitive tool for detection of mercury pollution to ensure food safety.