title: Implementing a two-layer feed-forward catalytic DNA circuit for enzyme-free and colorimetric detection of nucleic acids.
abstract: In the present study, a highly sensitive and specific bio-sensing platform for enzyme-free and colorimetric detection of nucleic acids has been developed. The biosensor is composed of two DNA nanostructures and two fuel strands that construct the foundation of a feed-forward catalytic DNA circuit. Upon binding the target strand to a specific DNA nanostructure, the circuit is run in order that at the end a hemin-binding aptamer, with the ability to convert a colorless substrate into a colored substance is released. Based on this strategy, 4 pM of the target DNA can be easily detected in serum samples by naked eyes after only a two-hour incubation with the circuit; meanwhile, if the incubation time is extended to 3 h, the biosensor can detect 1 pM of the target DNA. Besides the elevated sensitivity, the circuit can truly discriminate a spurious target containing one nucleotide mismatch with high specificity. Overall, the enzyme-free catalytic DNA circuit can be used as a sensitive alternative method to enzyme-based biosensors for the specific and cost-effective detection of nucleic acids.
authors.affiliation: Department of Biology, Faculty of Science, Shahid Bahonar University of Kerman, Kerman, Iran. Electronic address: ravan@uk.ac.ir.
authors.forename: Hadi
authors.initials: H
authors.lastname: Ravan
mesh_terms: D003124:Colorimetry / Q000379:methods*; D021881:DNA, Catalytic / Q000737:chemistry*; D049329:Nanostructures; D009696:Nucleic Acids / Q000097:blood*
chemical_list: D021881:DNA, Catalytic; D009696:Nucleic Acids
keywords: Colorimetric detection; DNA circuit; Feed-forward catalytic DNA circuit; HRP-Mimicking DNAzyme; Nucleic acids; Toehold exchange