Localization and delocalization of charges injected in DNA

TL;DR

This study investigates how charges injected into DNA behave differently depending on the DNA's physical state and deposition method, revealing conditions that lead to charge localization or delocalization, which affects DNA's electrical transport properties.

Contribution

It demonstrates the influence of DNA conformation and deposition techniques on charge localization and delocalization, providing insights into DNA's electrical conduction mechanisms.

Findings

Injected charges do not delocalize in overstretched DNA.

Spermidine-assisted deposition leads to charge delocalization over microns.

Deposition method impacts DNA's electrical transport behavior.

Abstract

The electrical properties of DNA molecules are investigated by charge injection and electric force microscopy experiments. Prior to injection, DNA molecules exhibit a weak positively charged state. We probe the electrical behaviour of DNA by measuring the localized or delocalized character of the DNA charge states upon injection of excess charges. We show that injected charges do not delocalize for overstretched DNA prepared by a receding meniscus technique, while the adjunction of spermidine during the deposition leads to relaxed DNA molecules exhibiting a charge delocalization over microns. The interplay between charge localization/delocalization and deposition techniques may explain that transport behaviors ranging from insulating to conductive have been reported for DNA deposited on surfaces.