Cation Enrichment Effect Modulated Nafion/Graphene Field-Effect Transistor for Ultrasensitive RNA Detection

The graphene field-effect transistor (GFET) biosensor serves as a foundational platform for detecting biomolecules, offering high conductivity, label-free operation, and easy integration. These features have garnered significant attention in biomarker detection. However, the presence of free cations in solution often leads to electrostatic shielding of negatively charged biomolecules, reducing GFET detection sensitivity (LOD ≥ 1 fM). Additionally, the limited capacitance change in GFET restricts its use as a response signal. This study introduces a cation enrichment electric field modulation strategy (CEEFMS) to enhance capacitance and Dirac voltage response during detection. The cation-enriched rough Nafion/graphene FET (CENG-FET) achieves RNA detection at the aM level. Utilizing total capacitance change and Dirac voltage shift as response signals, the CENG-FET demonstrates a wide linear range from 1 aM to 1 pM. These findings advance dual-signal detection strategies, reducing accidental inaccuracies in biomolecular sensing and paving the way for further research.