Electrochemical sensor for miRNA-34a detection: Synergistic signal amplification for robust and sensitive analysis

This study developed an electrochemical biosensor for the detection of miRNA-34a by integrating a synergistic signal amplification strategy that combined the electrocatalytic properties of reduced graphene oxide (rGO) with the enzymatic activity of double-stranded specific nuclease (DSN), while employing magnetic separation technology to ensure robust interference resistance. The biosensor was constructed by electrodepositing rGO onto a glassy carbon electrode via cyclic voltammetry (CV), utilizing its electrocatalytic activity to enhance the electrochemical response. Simultaneously, the presence of target miRNA-34a initiated a DSN-mediated enzymatic cyclic reaction, resulting in secondary signal amplification. The incorporation of magnetic nanoparticle separation technology effectively reduced nonspecific absorption and background interference, enabling accurate determination of the target miRNA. The biosensor demonstrated exceptional detection performance, achieving quantitative detection of miRNA-34a across a broad linear range (50.0 fM to 1.0 nM) with a detection limit of 16.6 fM. In spike-recovery assays using human plasma samples, the sensor reliably measured miRNA-34a at varying concentrations, confirming its robust anti-interference capability in complex biological matrices. These findings suggest that the proposed biosensor has significant potential for clinical diagnostics and real-sample analysis applications.