DNA-Templated Click Ligation Chain Reaction Catalyzed by Heterogeneous Cu2O for Enzyme-Free Amplification and Ultrasensitive Detection of Nucleic Acids

Nucleic acids play a pivotal role in the diagnosis of diseases. However, rapid, cost-efficient, and ultrasensitive identification of nucleic acid targets still represents a significant challenge. Herein, we describe an enzyme-free DNA amplification method capable of achieving accurate and ultrasensitive nucleic acid detection via DNA-templated click ligation chain reaction (DT-CLCR) catalyzed by a heterogeneous nanocatalyst made of Cu₂O (hnCu₂O). This hnCu₂O-DT-CLCR method is built on two cross-amplifying hnCu₂O-catalyzed DNA-templated azide-alkyne cycloaddition-driven DNA ligation reactions that boast a fast reaction rate and a high DNA ligation yield in minutes, enabling rapid exponential amplification of specific DNA targets. This newly developed hnCu₂O-DT-CLCR-enabled DNA amplification strategy is further integrated with two signal reporting mechanisms to achieve low-cost and easy-to-use biosensors: an electrochemical sensor through the conjugation of a methylene blue redox reporter to a DNA probe used in hnCu₂O-DT-CLCR and a colorimetric sensor through the incorporation of the split-to-intact G-quadruplex DNAzyme encoded into hnCu₂O-DT-CLCR. Both sensors are able to achieve specific detection of the intended DNA target with a limit of detection at aM ranges, even when challenged in complex biological matrices. The combined hnCu₂O-DT-CLCR and sensing strategies offer attractive universal platforms for enzyme-free and yet efficient detection of specific nucleic acid targets.