Surfactant modified deoxyribonucleic acid films: synthesis, interaction with acridine orange and luminescent properties

Abstract

Dye-doped deoxyribonucleic acids (DNA)–tetradecyltrimethylammonium (TTA) films have been prepared. Acridine orange, known as a DNA-binding molecule, can be spontaneously doped by immersing the DNA–TTA film in an acetonitrile solution of the dye. Dye-doped samples exhibit two characteristic absorption bands corresponding to the dye monomer and aggregate, respectively. With the elapse of time after immersion, dye molecules undergo an unusual transformation from the aggregate state to the monomer state, and photoluminescence intensity also increases. Dye molecules in the sample exhibit a pronounced enhancement in their photoluminescence intensity than those in PMMA. The photoluminescence intensity of the samples strongly correlates to both of the dye concentration and monomer/(monomer + aggregates) ratio. Not only the hydrophobic interaction but also the electrostatic force between DNA and dyes play important roles in the formation of the dye-doped samples. It is surmised that monomers and aggregates disperse within the hydrophobic TTA sites in the early stage, and then a part of monomers presumably intercalate between adjacent base pairs of DNA with the elapse of time.