A Spatial Confinement Effect-Based “Swing Probe” In Situ Entropy-Driven Assembly for the Sensitive Ratiometric Electrochemical Detection of Exosomal miRNA

-mediated electrocatalytic signal amplification reaction was further employed to realize significant signal response by utilizing the DNA nanostructures' passivation effect on the electrode. The developed biosensor exhibited an ultralow LOD of 4.08 fM and successfully distinguished hepatocellular carcinoma (HCC) patients from healthy donors. Overall, this study provides a novel approach for exosomal miRNA detection and holds promise for advancing miRNA-based liquid biopsy in early cancer diagnosis.