Structure of DNA-CTAB-hexanol complexes.

We have probed structures of the complexes formed by DNA with the cationic surfactant cetyltrimethylammonium bromide in the presence of the cosurfactant hexanol, using small angle x-ray diffraction techniques. They are found to exhibit a hexagonal-->lamellar-->hexagonal transition with increasing hexanol content. Quantitative analysis of the diffraction data shows that the complexes formed at low hexanol concentrations have an intercalated hexagonal (HI) structure, whereas those formed at higher hexanol content have an inverted hexagonal (HII) structure.