Exciton energy transfer-based fluorescent sensor for the detection of Hg2+ through aptamer-programmed self-assembly of QDs.

Herein, an original exciton energy transfer-based sensitive fluorescence sensor for the determination of Hg2+ has been designed through DNA aptamer-programmed self-assembly of CdTe quantum dots (QDs). In this work, CdTe QDs were applied as fluorescence signal source. The two pieces of T-rich aptamer played a role as molecular recognition probes which could bind to the target Hg2+ specifically. The extent of Hg2+-triggered self-assembly of QDs depended on the concentration of Hg2+, which resulted in an exciton energy transfer effect between QDs, giving an obvious fluorescence signal decrease and red-shift of the fluorescent peak. Based on this principle, we could detect the Hg2+ in two different signal modes. The limit of detection (LOD) was 3.33 nM. The proposed sensing method exhibited its application in detecting Hg2+ in real water samples with satisfactory performance. The results indicated that this proposed sensor will be of great potential in biological and analytical fields.