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Nat Commun. 2019 Feb 8;10(1):685. doi: 10.1038/s41467-019-08531-4.

Conformations and cryo-force spectroscopy of spray-deposited single-strand DNA on gold.

Author information

1
Department of Physics, University of Basel, Klingelbergstrasse 82, 4056, Basel, Switzerland. remy.pawlak@unibas.ch.
2
Department of Physics, University of Basel, Klingelbergstrasse 82, 4056, Basel, Switzerland.
3
Departamento de Física Teórica de la Materia Condensada, Universidad Autónoma de Madrid, E-28049, Madrid, Spain.
4
Otto Schott Institute of Materials Research, Friedrich Schiller University Jena, D-07742, Jena, Germany.
5
Departamento de Física Teórica de la Materia Condensada, Universidad Autónoma de Madrid, E-28049, Madrid, Spain. ruben.perez@uam.es.
6
Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, E-28049, Madrid, Spain. ruben.perez@uam.es.
7
Department of Physics, University of Basel, Klingelbergstrasse 82, 4056, Basel, Switzerland. ernst.meyer@unibas.ch.

Abstract

Cryo-electron microscopy can determine the structure of biological matter in vitrified liquids. However, structure alone is insufficient to understand the function of native and engineered biomolecules. So far, their mechanical properties have mainly been probed at room temperature using tens of pico-newton forces with a resolution limited by thermal fluctuations. Here we combine force spectroscopy and computer simulations in cryogenic conditions to quantify adhesion and intra-molecular properties of spray-deposited single-strand DNA oligomers on Au(111). Sub-nanometer resolution images reveal folding conformations confirmed by simulations. Lifting shows a decay of the measured stiffness with sharp dips every 0.2-0.3 nm associated with the sequential peeling and detachment of single nucleotides. A stiffness of 30-35 N m-1 per stretched repeat unit is deduced in the nano-newton range. This combined study suggests how to better control cryo-force spectroscopy of adsorbed heterogeneous (bio)polymer and to potentially enable single-base recognition in DNA strands only few nanometers long.

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