# DNA-Decorated PET Nanochannels for Sensitive Biosensing

## TL;DR

Researchers created DNA-decorated nanochannels in PET membranes to study how surface charge affects ion transport and improve biosensing capabilities.

## Contribution

A novel DNA functionalization strategy for PET nanochannels to control ion transport via outer surface charge effects.

## Key findings

- High-valence cations like Ru(NH3)63+ showed greater ionic current rectification in DNA-functionalized PET nanochannels.
- COMSOL simulations confirmed the influence of ion valence and surface charge density on ion transport.
- The tip region of conical nanochannels is critical for modulating ion transport properties.

## Abstract

Functionalized nanochannels are crucial for achieving excellent ion transport properties and enable versatile applications such as ion gating, biosensing, and energy conversion. Conical single nanochannels were fabricated in single-ion-track polyethylene terephthalate (PET) membranes using the ion-track-etching method. Leveraging the high programmability of deoxyribonucleic acid (DNA) strands, a series of DNA molecules were designed to functionalize the outer surface at the tip region (small opening) of the conical PET nanochannels. This approach enabled precise regulation of both spatial charge distribution and steric hindrance on the outer surface, enabling the investigation of ion transport properties under the dominance of outer surface charge effects across ions of different valences. In contrast to the low-valence K+, the high-valence cation Ru(NH3)63+ exhibited far greater enhancement in ionic current rectification (ICR) within PET films functionalized with DNA of varying charge densities. We used COMSOL simulations to corroborate that higher-valence ions exert more pronounced effects on ion transport in conical nanochannels with greater outer surface charge density. Furthermore, it was confirmed that the tip region plays a critical role in modulating the ion transport properties of conical nanochannels, thereby validating outer surface functionalization as a rational and efficient strategy.