Electrochemiluminescence aptasensor for multiple determination of Hg2+ and Pb2+ ions by using the MIL-53(Al)@CdTe-PEI modified electrode

An aptasensor based on MIL-53(Al)@CdTe was designed for multiple determination of Hg2+ and Pb2+ by electrochemiluminescence (ECL). Upon the recognition of Hg2+, aptamer 2-AuNPs form hairpin structures and are removed from the electrode. While in the presence of Pb2+, aptamer 1-PtNPs capture the target ions and form G-quadruplexes, and then bring PtNPs close enough to CdTe QDs to produce ECL resonance energy transfer. Upon aptamer interaction with Hg2+ and Pb2+, decreased ECL intensity was observed due to enhanced resonance energy transfer (ERET) and attenuated surface plasmon resonance (SPR). The ECL intensity difference (ΔECL) could therefore be used to detect heavy-metal ions with detection limits of 4.1 × 10−12 M (path 1, Hg2+), 3.7 × 10−11 M (path 2, Pb2+), and 2.4 × 10−11 M (path 3, Pb2+). The aptasensor could also be used for detecting Hg2+ and Pb2+ in fish and shrimp samples with good recoveries.