Localization and delocalization of charges injected in DNA

Thomas Heim (1) , Thierry Melin (1) , D. Deresmes (1) , Dominique Vuillaume (1)

1 IEMN - Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520

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.

Mots clés: DNA; electrical transport; EFM

Domaines: Science des matériaux [cond-mat.mtrl-sci]; Systèmes mésoscopiques et effet Hall quantique [cond-mat.mes-hall]; Biophysique [physics.bio-ph]

Thomas Heim, Thierry Melin, D. Deresmes, Dominique Vuillaume. Localization and delocalization of charges injected in DNA. 2004. ⟨hal-00002773⟩