Preparations of DNA-aligned thin films by cast and LB methods and their anisotropic electric conductivity along DNA strands in the film

Abstract

Organic thin films in which DNA double strands aligned in one direction were prepared by two methods: i) the polyion complex of DNA anions and cationic amphiphiles was prepared, the organic solution of the DNA-lipid complex was cast on the plate, and the obtained transparent film was stretched in one direction, and ii) DNA anions were solubilized in subphase with intercalated dyes and were transferred with cationic lipid monolayers by vertical dipping method. DNA strands could be aligned along stretching direction in the cast film and along dipping direction in the Langmuir-Blodgett (LB) film. The orientation of DNA strands in these thin films was confirmed by X-ray diffraction and polarized absorption spectra. The DNA-aligned films prepared by both cast-stretching and LB methods showed a large anisotropic and ohmic electric current (10-3- 10-5 S cm-1 ratio = 104) along DNA strands in the film.