Label-free fluorescence aptasensor for the detection of cadmium(II) ion based on the conformational switching of aptamer and thioflavine T.

Abstract

A simple label-free Cd2+ fluorescent aptasensor was proposed using aptamer as a recognition element and thioflavine T (ThT) as a signal reporter. The presence of Cd(II) can induce the conformational switching of the aptamer probe, accompanied by a change in fluorescence intensity. According to the difference in fluorescence signals before and after the addition of Cd2+, a fluorescence sensor for Cd2+ assay was established. Under the better experimental conditions, the sensor displayed a good linear range from 2 to 50nM and the excellent detection limit was 0.8nM. The method demonstrated high sensitivity and good selectivity. The aptasensor could detect Cd2+ in simulated water samples with satisfactory results. The proposed method had obvious advantages that was without chemical modification of fluorescent groups and complicated target preconcentration. It provided a new analytical platform for the detection of heavy metal ion pollution in environmental and biomedical fields.