Pore-in-pore nanoscaffolds in glass microtubes deliver selective K+ sensing and INHIBIT logic gate

Solid-state biomimetic channels are attractive for label-free ion analysis, but their performance is often undermined by fragile functional layers confined within narrow nanopores. Here we report a pore-in self-assembly strategy that integrates silica nanotubes (SiO 2 NTs) into a glass microtube (GMT) to construct a robust, label-free potassium ion (K + ) sensor. Thiol-functionalized SiO 2 NTs, possessing hollow tubular morphology and abundant surface anchoring groups, are capillary-wicked into the GMT lumen where they spontaneously assemble into a continuous three-dimensional porous scaffold. This hierarchical architecture effectively stabilizes the ion transport pathway and recognition sites, preventing functional disintegration under electric field-induced translocation. This platform enables detection of target potassium ion down to 0.597 μM, even at concentrations of other metal ions up to five times higher. Furthermore, by leveraging the reversible folding behavior of G4 DNA in response to potassium ion and 18-crown-6 ether, an INHIBIT logic gate was constructed that translates dual chemical inputs into discrete electrical output. This pore-in architecture combines simplicity, label-free operation, and robustness, demonstrating broad potential for intelligent ion sensing and molecular logic operations in complex environments.