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Angew Chem Int Ed Engl. 2020 Mar 24. doi: 10.1002/anie.202002019. [Epub ahead of print]

A Multi-component All-DNA Biosensing System Controlled by a DNAzyme.

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McMaster University, Biochemistry and Biomedical Sciences, CANADA.
McMaster University, Chemistry and Chemical Biology, CANADA.
McMaster University, Biochemistry and Biomedical Sciences, 1280 Main Street West, L8S4K1, Hamilton, CANADA.


We report on a programmable all-DNA biosensing system that centers on the use of a 4-way junction (4WJ) to transduce a DNAzyme reaction into an amplified signal output.  A target acts as a primary input to activate an RNA-cleaving DNAzyme, which then cleaves an RNA-containing DNA substrate that is designed to be a component of a 4WJ.  The formation of the 4WJ controls the release of a DNA output that becomes an input to initiate catalytic hairpin assembly (CHA), which produces a second DNA output that controls assembly of a split G-quadruplex as a fluorescence signal generator. The 4WJ can be configured to produce either a turn-off or turn-on switch to control the degree of CHA, allowing target concentration to be determined in a quantitative manner. We demonstrate this approach by creating a sensor for Escherichia coli, a model bacterial pathogen, demonstrating the utility of using RNA-cleaving DNAzymes to modulate DNA assembly and reassembly. The method can detect as low as 50 E. coli cells/mL within 85 minutes and offers an amplified bacterial detection method that does not require a protein enzyme.


DNA assembly; DNAzyme; RNA cleavage; bacterial pathogen; catalytic hairpin assembly


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