Probing Inner-Tip Access-Resistance Modulation by ssDNA in a Nanopipette Using a Single-Molecule Nanomanipulation System.

Authors

Wenhao Ma, Yongjia Wang, Shaoxi Fang, Shixuan He, Yajie Yin, Bohua Yin, Rong Tian, Ting Weng, Wanyi Xie, Changjun Hou, Danquan Huo, Deqiang Wang

Published in

Nano letters. Volume 26. Issue 42. Pages 14708-14716. Oct 28, 2026.

Abstract

The transport of flexible polyelectrolytes through nanoscale confinements is fundamental to polymer physics and biophysics, yet direct observation remains challenging. Using a nanopipette-based single-molecule nanomanipulation platform, we controllably translocate long single-stranded DNA (ssDNA) through a solid-state nanopore, enabling real-time tracking of chain dynamics with nanoscale precision. We discover that ssDNA generates a characteristic progressive current decrease with terminal oscillations─absent for rigid double-stranded DNA. Evidence indicates this signal arises from inner-tip access-resistance modulation by the ssDNA coil, with a linear relationship between current blockade and relative escape displacement. Systematic variation of voltage and nanopore geometry reveals electric-field-driven stretching of the ssDNA coil and extended interaction with the inner tip region. This provides a framework for interpreting flexible polyelectrolyte transport under nanoconfinement, with implications for polymer physics, nuclear pore transport, and intrinsically disordered proteins.

PMID:
42949388
Bibliographic data and abstract were imported from PubMed on 28 Oct 2026.

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