Honeycomb-patterned films fabricated by self-organization of DNA-surfactant complexes

In this paper, DNA-based honeycomb films were successfully constructed from a simple solution casting process at high relative humidity, through the encapsulation of DNA with a cationic surfactant ditetradecyldimethylammonium (DTDA). Cationic surfactants electrostatically attach to phosphate anions of DNA in a molar ratio of 1:1 in the DNA-DTDA complex. Investigation of the effects of substrate, concentration, and solvent on the morphology of the microporous films demonstrated the wide generality and high reproducibility of the formation of DNA-DTDA self-organized microporous films. The morphology of the microporous structures can be adjusted by slightly changing the concentration of the complex solution. DNA exists in the double helical B-form in the microporous film confirmed by circular dichroism spectrum. Dye molecule rhodamine B was loaded into the DNA-DTDA complex, presenting a fluorescent microporous film. DNA-DTDA complex as a host material provides a new method for tailoring fluorescent microporous films. The DNA-based ordered honeycomb films should be attractive for use in optical and optoelectronic devices, separation, ion transportation, and biosensors.

Preparation and characterization of DNA films induced by UV irradiation

Large amounts of DNA-enriched materials, such as salmon milts and shellfish gonads, are discarded as industrial waste. We have been able to convert the discarded DNA to a useful material by preparing novel DNA films by UV irradiation. When DNA films were irradiated with UV light, the molecular weight of DNA was greatly increased. The reaction was inhibited by addition of the radical scavenger galvinoxyl suggesting that the DNA polymerization with UV irradiation proceeded by a radical reaction. Although this UV-irradiated DNA film was water-insoluble and resistant to hydrolysis by nuclease, the structure of the DNA film in water was similar to non-irradiated DNA and maintained B-form structure. In addition, the UV-irradiated DNA film could effectively accumulate and condense harmful DNA-intercalating compounds, such as ethidium bromide and acridine orange, from diluted aqueous solutions. The binding constant and exclusion number of ethidium bromide for UV-irradiated DNA were determined to be 6.8 +/- 0.3 x 10(4) M(-1) and 1.6 +/- 0.2, respectively; these values are consisted with reported results for non-irradiated DNA. The UV-irradiated DNA films have potential uses as a biomaterial filter for the removal of harmful DNA intercalating compounds.