DNAzyme Molecular Beacon Probes for Target-Induced Signal-Amplifying Colorimetric Detection of Nucleic Acids

摘要

A novel DNAzyme molecular beacon (DNAzymeMB) strat-negy was developed for target-induced signal-amplifyingncolorimetric detection of target nucleic acids. ThenDNAzymeMB, which exhibits peroxidase activity in its freenhairpin structure, was engineered to form a catalyticallyninactive hybrid through hybridization with a blocker DNA.nThe presence of target DNA leads to dissociation of thenDNAzymeMB from the inactive hybrid through hybridiza-ntion with the blocker DNA. This process results innrecovery of the catalytically active DNAzymeMB, whichncan catalyze a colorimetric reaction that signals thenpresence of the target DNA. In addition, a primer wasnrationally designed to anneal to the blocker DNA of thenblocker/target DNA duplex and displace the bound targetnDNA during the extension reaction. The released targetnDNA triggers the next cycle involving hybridization withnblocker DNA, DNAzymeMB dissociation, primer exten-nsion, and target displacement. This unique amplifyingnstrategy leads to the generation of multiple numbers ofnactive DNAzymeMB molecules from a single target mol-necule and gives a detection limit down to 1 pM, a valuenthat is nearly 3 or 5 orders of magnitude lower than thosenof previously reported DNAzyme molecular beacon-basednDNA detection methods.