A dual-mode biosensor coupling electrochemical and fluorescent measurements of single nucleotide polymorphism with enzyme-free cascade amplification

Enzyme-free amplification techniques empower the easy-operable and cost-effective analysis of single nucleotide polymorphisms (SNPs), which garnered considerable extensive attention. However, the sensitivity and reliability of enzyme-free amplification technology are limited to meet the needs of biomedical diagnosis. Herein, we develop a dual-mode biosensing strategy that combines target-induced double DNA release and enzyme-free amplification for both electrochemical and fluorescent SNP detections. This strategy utilizes mutant SNP to activate entropy-driven amplifier (EDA) system, a cyclic strand displacement reaction, achieving the release of two single-strand DNA. These EDA by-products of target-induced release are ingeniously used as synchronized inputs for electrochemical and fluorescent measurements to fabricate circularly amplified hybridization chain reaction (HCR) and catalytic hairpin reaction (CHA) respectively. Such flexible strategy of dual-mode biosensing platform can not only make effective use of EDA by-products originally wasteful to elevate identification and amplification efficiency, but also improve the detection reliability. Moreover, leveraging the programmability and integration of classical enzyme-free cascaded amplification, this dual "signal-on" biosensor flexibly achieves high sensitivity detection and good selectivity, which holds great promise in the fields of early disease diagnosis.