Langmuir isotherm analysis of novel branched per-fluorinated surfactants and their interactions with single stranded DNA

The efficient synthesis and surface properties of new fluorinated gemini surfactants are described. The aim of this study was to investigate the relationships between the molecular structure and the Langmuir layer properties of these fluorinated gemini lipids. The electrostatic ssDNA binding interactions of amino groups included on the spacer were also investigated. The synthesis corresponds to the substitution of vinyl fluorine atom of fluoro-unsaturated esters by a diethylene-oxide diamine via a Michael addition followed by a fluoride elimination reaction. For the spread layers, the measurements of surface pressure versus molecular area were performed with or without ssDNA in the subphase. The monolayers characteristics depend on the hydrophobic chain length, the polar-head, the pH of the subphase and the flexibility of the spacer. The introduction of ssDNA in the subphase seems to show a low interaction between the surfactants and the oligonucleotide.

The synthesis of gemini-type fluorinated surfactants with ester and acid polar heads connected with diaminoethoxylated spacer is described. By combining two rigid fluorinated hydrophobic tags and a flexible ethylenoxide moiety, one can design original gemini lipids, which are able to bind ssDNA. The aminoethoxylated polar head might undergo conformational changes so that the DNA complexation could occur.Figure optionsDownload as PowerPoint slideHighlights
► Secondary amine fluorinated gemini surfactants were synthesised by simple and efficient methods.
► Fluorinated lipids form stable monolayer at the air/water interface.
► Their self-assembling properties depend on the pH of the subphase, the polar head and the F-tag lengths.
► 2D self assembling provides good models for the study of DNA–cell membranes interactions.