Nucleic Acid-Induced Tetraphenylethene Probe Noncovalent Self-Assembly and the Superquenching of Aggregation-Induced Emission

Superquenching of aggregation-induced emission (AIE) has been utilized in biosensing for the first time. A positively charged tetraphenylethene derivative (compound 1) showed no emission in an aqueous buffer solution. A single-stranded DNA (a polyanion) induced aggregation of compound 1, and strong compound 1 aggregate emission was observed. When the DNA was labeled with a quencher molecule, compound 1 aggregate emission was efficiently quenched. On the basis of this observation, a new, simple, sensitive and selective DNA methyltransferase (MTase) assay has been developed. A quencher-labeled double-stranded DNA could induce aggregation of compound 1, and superquenching of compound 1 AIE was observed. In the presence of MTase and an endonuclease, the DNA could be specifically methylated and cleaved into single-stranded DNA fragments. The quencher molecule was released, and a turn-on emission signal was detected.