In Situ Growth of Polyanionic DNA Hydrogel Networks for Nanoconfined Iontronic Analysis of DNA Methylation

Solid-state nanofluidics offers unique ion transport dynamics for sensitive molecular diagnostics. Herein, we report a nanoconfined iontronic platform for quantifying trace p16 gene methylation (p16-mC) in liquid biopsies. This system couples sequence-specific hybridization with HpaII enzymatic cleavage to strictly eliminate false positives from unmethylated homologues. Genuine target recognition triggers interfacial rolling circle and multiple-primer chain amplifications directly at anodic aluminum oxide nanochannel orifices. This in situ topological growth yields a 3D polyanionic DNA hydrogel that fundamentally remodels the interfacial physicochemical microenvironment. The resulting superhydrophilic transition and localized surface charge accumulation synergistically amplify transmembrane cation conductance, translating subtle epigenetic variations into robust iontronic readouts. Driven by this physical gating, the sensor achieves an ultralow detection limit of ∼33 aM and a dynamic range spanning 10 orders of magnitude. Clinically, the platform effectively discriminates nonsmall cell lung cancer patients from healthy donors using peripheral plasma, demonstrating its clinical feasibility for noninvasive cancer diagnostics.