Direct visualization of charge transport in suspended (or free-standing) DNA strands by low-energy electron microscopy

TL;DR

This paper demonstrates the use of low-energy electron microscopy to simultaneously image the structure and charge distribution of suspended DNA molecules at nanometer resolution, revealing charge transport behavior.

Contribution

It introduces a method for high-resolution imaging of both structure and charge in individual biomolecules using low-energy electrons, enabling new insights into charge transport.

Findings

Achieved ~1 nm resolution imaging of DNA molecules.

Detected charge of less than one elementary charge per nanometer.

Observed correlated charge redistribution between DNA regions.

Abstract

Low-energy electrons offer a unique possibility for long exposure imaging of individual biomolecules without significant radiation damage. In addition, low-energy electrons exhibit high sensitivity to local potentials and thus can be employed for imaging charges as small as a fraction of one elementary charge. The combination of these properties makes low-energy electrons an exciting tool for imaging charge transport in individual biomolecules. Here we demonstrate the imaging of individual deoxyribonucleic acid (DNA) molecules at the resolution of about 1 nm with simultaneous imaging of the charging of the DNA molecules that is of the order of less than one elementary charge per nanometer. The cross-correlation analysis performed on different sections of the DNA network reveals that the charge redistribution between the two regions is correlated. Thus, low-energy electron microscopy is capable to provide simultaneous imaging of macromolecular structure and its charge distribution which can be beneficial for imaging and constructing nano-bio-sensors.