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

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.