TDAB-induced DNA plasmid condensation on the surface of a reconstructed boron doped silicon substrate
Fiche publication
Date publication
janvier 2008
Auteurs
Membres identifiés du Cancéropôle Est :
Pr FROMM Michel
Tous les auteurs :
Mougin A, Babak VG, Palmino F, Beche E, Baros F, Hunting DJ, Sanche L, Fromm M
Lien Pubmed
Résumé
Our study aims at a better control and understanding of the transfer of a complex [DNA supercoiled plasmid - dodecyltrimethylammonium surfactant] layer from a liquid-vapour water interface onto a silicon surface without any additional cross-linker. The production of the complexed layer and its transfer from the aqueous subphase to the substrate is achieved with a Langmuir-Blodgett device. The substrate consists of a reconstructed boron doped silicon substrate with a nanometer-scale roughness. Using X-ray photoelectron spectroscopy and atomic force microscopy measurements, it is shown that the DNA complexes are stretched in a disorderly manner throughout a 2-4 nm high net-like structure. This architecture is composed of tilted cationic surfactant molecules bound electrostatically to DNA, which exhibits a characteristic network arrangement with a measured average fiber diameter of about 45 +/- 15 nm covering the entire surface. The mechanism of transfer of this layer onto the planar surface of the semi-conductor and the parameters of the process are analysed and illustrated by atomic force microscopy snapshots. The molecular layer exhibits the typical characteristics of a spinodal decomposition pattern or dewetting features. Plasmid molecules appear like long flattened fibers covering the surface, forming holes of various shapes and areas. The cluster-cluster aggregation of the complex structure gets very much denser on the substrate edge. The supercoiled DNA plasmids undergo conformational changes and a high degree of condensation and aggregation is observed. Perspectives and potential applications are considered. (C) 2007 Elsevier B.V. All rights reserved.
Référence
Surf Sci. 2008 Jan 1;602(1):142-50