Distinct mechanisms of DNA sensing based on N-doped carbon nanotubes with enhanced conductance and chemical selectivity

TL;DR

This study uses first-principles calculations to explore how N-doped carbon nanotubes can detect DNA bases through different conductance mechanisms, revealing distinct sensing modes for face-on and edge-on configurations.

Contribution

It uncovers a novel edge-on sensing mechanism based on chemical connectivity and dual electron donor-acceptor roles of N-doped CNTs, advancing DNA sequencing technology.

Findings

Face-on configuration shows conventional conductance order with guanine highest.

Edge-on configuration reveals thymine as the largest signal due to a new sensing mechanism.

N-doped CNTs can act as both electron donors and acceptors, enabling chemical connectivity-based sensing.

Abstract

Carrying out first-principles calculations, we study N-doped capped carbon nanotube (CNT) electrodes applied to DNA sequencing. While we obtain for the face-on nucleobase junction configurations a conventional conductance ordering where the largest signal results from guanine according to its high highest occupied molecular orbital (HOMO) level, we extract for the edge-on counterparts a distinct conductance ordering where the low-HOMO thymine provides the largest signal. The edge-on mode is shown to operate based on a novel molecular sensing mechanism that reflects the chemical connectivity between N-doped CNT caps that can act both as electron donors and electron acceptors and DNA functional groups that include the hyperconjugated thymine methyl group.