Ultrasensitive and Highly Selective Detection of Calcium Ions Using KD 5 -Modified Asymmetric Nanochannels

Artificial solid-state nanochannels have attracted significant interest as promising nanofluidic tools for ion/molecule detection, DNA sequencing, and biomimetic applications. In this work, we designed an aspartic acid-rich peptide, KD₅ (Lys-Asp₅, KDDDDD), via a green tag-assisted approach. Leveraging its strong Ca²⁺ recognition and coordination capability, KD₅ was covalently grafted onto the inner surface of asymmetric nanochannels, inspired by the in