Graphene Field-Effect Transistors Loaded with DNA Walkers for Detection of miRNAs

MicroRNAs, as pivotal post-transcriptional regulators of gene expression, are closely associated with major diseases. Precise detection of their expression abnormalities is of paramount importance for disease prevention and control. Although graphene field-effect transistors (GFETs) exhibit significant advantages in miRNA sensing, liquid-gate structures suffer from suboptimal stability, while back-gate structures are constrained by limited sensitivity, making it challenging to achieve simultaneous optimization of both. To address this issue, our study has innovatively constructed a biosensing platform that synergizes field-effect regulation with DNA walker-based signal amplification. This platform achieves directional immobilization of DNA walkers on GFETs via Au-S bonds. It utilizes target miRNA-141 to trigger cascade strand displacement reactions, and combines field-effect modulation with a DNA walker-driven signal cascade amplification mechanism. Additionally, it leverages a T7 exonuclease-assisted target recycling regeneration mechanism to realize a three-stage coordinated process of "target recognition-chain displacement-signal amplification". This platform achieves high sensitivity with an impressively low detection limit of 12.6 fM in the range of 0.1 pM to 1 μM for miRNA-141 detection, with signal output unrestricted by Debye length limitations. This design successfully resolves the inherent conflict between sensitivity and stability in GFETs, providing an innovative solution that combines high reliability with ultrasensitivity for clinical nucleic acid biomarker detection.