An ultrasensitive label-free electrochemical biosensor for microRNA-21 detection based on a 2'-O-methyl modified DNAzyme and duplex-specific nuclease assisted target recycling.

Based on a highly efficient 2'-O-methyl modified G-quadruplex-hemin DNAzyme and duplex-specific nuclease (DSN) assisted target recycling, a novel label-free electrochemical biosensor for microRNA-21 (miR-21) detection is developed here. By employing the strategy, this DNA biosensor can detect as low as 8 aM miR-21 and exhibits high discrimination ability even against a single-base mismatch.