Conductivity of Macroscopic DNA-Lipid Films

M. Mertig1, J. Richter1, U. Oertel2, D. Jenichen2, I. Mönch3, and W. Pompe1

1Institut für Werkstoffwissenschaft, Technische Universität Dresden, D-01062 Dresden, and 2Institut für Polymerforschung Dresden, Postfach 12 04 11, D-01005 Dresden, and 3Institut für Festkörper- und Werkstoffforschung Dresden, Postfach 27 00 16, D-01171 Dresden, Germany

e-mail: mertig@tmfs.mpgfk.tu-dresden.de
 

Self-standing DNA-lipid films have been prepared by mixing cationic amphiphiles in aqueous solution with DNA, resolving the precipitated DNA-lipid complex in organic solvent and casting the solution. X-ray spectroscopy reveals that the obtained flexible films consist of domains of aligned DNA strands, isolated from each other by lipid molecules. Thus, electric measurements allow to determine the macroscopic conductivity of a large ensemble of parallel arranged DNA strands. From this measurements the resistivity of a single DNA strand can be estimated to be > 1010 Ohm/nm.

Depending on the particular amphiphile used, specific electric response of the films have been observed in dynamical measurements. The corresponding electrical circuit diagrams will be discussed on the basis of structure models for the DNA-lipid films.