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.
Highlights
Charge transport through deoxyribonucleic acid (DNA) molecules has been a highly interesting subject over the past few decades in view of the potential for building bio-nano-electronic devices[1,2,3]
A typical inline hologram of single stranded DNA (ssDNA) fibers acquired with this setup is shown in Fig. 1c, exhibiting ssDNA fibers perfectly stretched over the lacey carbon support
An individual hologram is shown in Fig. 2a, where one can see ssDNA fibers stretched over holes in lacey carbon
Summary
Charge transport through deoxyribonucleic acid (DNA) molecules has been a highly interesting (and controversial) subject over the past few decades in view of the potential for building bio-nano-electronic devices[1,2,3]. Www.nature.com/scientificreports albumin, cytochrome C and hemoglobin)[23] Most of these results were obtained by imaging individual molecules stretched over holes in carbon films[15,16,17,18,19,20,21]. Such a sample arrangement creates an unwanted so-called biprism effect. Low-energy electrons exhibit high sensitivity to local potentials[26] allowing imaging individual charges as small as a fraction of an elementary charge[27,28,29] This is why low-energy electron imaging is a unique tool to probe charge effects in DNA molecules at high spatial resolution and at high sensitivity to the smallest amount of charge
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