A simple electrochemical biosensor for highly sensitive and specific detection of microRNA based on mismatched catalytic hairpin assembly

A dual target-recycling amplification strategy for sensitive detection of microRNAs based on duplex-specific nuclease and catalytic hairpin assembly

A dual target-recycling amplification strategy for sensitive detection of microRNAs based on duplex-specific nuclease and catalytic hairpin assembly was reported for the first time.

Ultrasensitive detection of microRNAs using catalytic hairpin assembly coupled with enzymatic repairing amplification

A novel isothermal nucleic acid amplification technology is developed by coupling CHA with enzymatic repairing amplification for sensitive and selective miRNA detection.

Isothermal Amplification of Nucleic Acids

Isothermal amplification of nucleic acids is a simple process that rapidly and efficiently accumulates nucleic acid sequences at constant temperature. Since the early 1990s, various isothermal amplification techniques have been developed as alternatives to polymerase chain reaction (PCR). These isothermal amplification methods have been used for biosensing targets such as DNA, RNA, cells, proteins, small molecules, and ions. The applications of these techniques for in situ or intracellular bioimaging and sequencing have been amply demonstrated. Amplicons produced by isothermal amplification methods have also been utilized to construct versatile nucleic acid nanomaterials for promising applications in biomedicine, bioimaging, and biosensing. The integration of isothermal amplification into microsystems or portable devices improves nucleic acid-based on-site assays and confers high sensitivity. Single-cell and single-molecule analyses have also been implemented based on integrated microfluidic systems. In this review, we provide a comprehensive overview of the isothermal amplification of nucleic acids encompassing work published in the past two decades. First, different isothermal amplification techniques are classified into three types based on reaction kinetics. Then, we summarize the applications of isothermal amplification in bioanalysis, diagnostics, nanotechnology, materials science, and device integration. Finally, several challenges and perspectives in the field are discussed.

DNA transducer-triggered signal switch for visual colorimetric bioanalysis

A simple and versatile colorimetric biosensor has been developed for sensitive and specific detection of a wide range of biomolecules, such as oligonucleotides and aptamer-recognized targets. Combining the signal transducer and catalyzed hairpin assembly (CHA)-based signal amplification, the target DNA binds with the hairpin DNA to form a new nucleic acid sequence and creates a toehold in the transducer for initiating the recycle amplification reaction of CHA. The catalyzed assembly process produces a large amount of G-rich DNA. In the presence of hemin, the G-rich DNA forms G-quadruplex/hemin complex and mimic horseradish peroxidase activity, which catalyzes a colorimetric reaction. Under optimal conditions, the calibration curve of synthetic target DNA has good linearity from 50 pM to 200 nM with a detection limit of 32 pM. This strategy has been successfully applied to detect S. pneumoniae as low as 156 CFU mL(-1), and shows a good specificity against closely related streptococci and major pathogenic bacteria. In addition, the developed method enables successful visual analysis of S. pneumoniae in clinical samples by the naked eye. Importantly, this method demonstrates excellent assay versatility for sensitively detecting oligonucleotides or aptamer-recognized targets.

A novel and versatile nanomachine for ultrasensitive and specific detection of microRNAs based on molecular beacon initiated strand displacement amplification coupled with catalytic hairpin assembly with DNAzyme formation

A simple and versatile strategy for ultrasensitive and specific detection of microRNAs based on strand displacement amplification and catalytic hairpin assembly.

A new mode for highly sensitive and specific detection of DNA based on exonuclease III-assisted target recycling amplification and mismatched catalytic hairpin assembly

Schematic representation of the designed strategy for target DNA detection.