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영어

Detection of heavy metal ions in aqueous system including human blood plasma is an important issue because of their adverse effects on human health and the environments. Among them, Pb2+, and Hg2+ are the major elements requiring a critical caution because of the severe health effects. While various detection methods have been developed, the heavy metal specific oligonucleotides such as metal dependent DNAzyme and Hg2+ aptamers have led to significant improvement for the detection sensitivity and specificity. However, further improvement for the detecting sensitivity and feasibility are still open. Specially, no scheme is reported to detect Pb2+ and Hg2+ simultaneously. In case of heavy metal dependent DNAzymes, there should be a false
positive signal change because of the nearly similar sequences of the substrate oligonucleotides. For the dual detection, a fluorescence signal change is more suitable rather than color change in the presence of the metal ions. However, the conformation of the reported Hg2+ aptamers deforms in a signal decrease way which should be less sensitive to the metal ion than fluorescence-on based methods. Therefore, we devised a scheme to generate fluorescence signal combining the DNAzyme and aptamer on gold nanoparticles which act as a super quencher for two different fluorophores ;,one is linked to the substrate and the other is linked to aptamer. In the presence of the metal ions, the fluorescence signal can be turned on because of the enzymatic cleavages of the substrate by DNAzymes for Pb2+ and the conformational change for Hg2+ whereas the nanoparticles are in latent in the absence of the metal ions. Until now up to 5 nM of Pb2+ is detectable within 20 minutes. Detection sensitivity for Hg2+ and specificity for the two metal ions will be presented in the conference.