Fluorescence Determination of Merucury(II) Using a Thymine Aptamer

A label-free thymine-rich sequence and a molecular beacon were synthesized to construct a highly sensitive and selective fluorescence probe for the determination of mercury(II). The aptamer of the thymine-rich sequence selectively bonded with mercury(II) with an accompanying change in the fluorescence intensity of the molecular beacon due to the higher affinity of the aptamer with mercury(II). The limit of detection was 12.7 nanomolar, and a linear relationship was obtained between the fluorescence and mercury(II) concentrations up to 1 micromolar. The assay was highly selective for the mercury(II) and not significantly affected by other metal ions.