Mixing behaviour of Pluronics with gemini surfactant/plasmid DNA condensates: effect of Pluronic composition

Nanoparticles prepared from plasmid DNA (pDNA) and N , N -bis(dimethylhexadecyl)-1,3-propanediammonium bromide (16-3-16) have been mixed with various Pluronic block copolymers and investigated as binary surfactant systems in water using the previously demonstrated critical aggregation concentration of the surfactant-DNA complex. Surface tensiometry was used to determine critical micelle concentrations of mixed micelles formed within these Pluronic/16-3-16/pDNA mixtures. Use of mixed micelle theories reveals that mixed micelle composition and the interaction parameter, β , are influenced by the structure, in particular hydrophobicity, of the Pluronic component. Ethidium bromide fluorescence studies demonstrate the ability of the Pluronics to de-condense the plasmid DNA from the cationic 16-3-16 gemini surfactant complex, and show some relationship to the interaction parameter and Pluronic composition. Non-ideal mixing behaviour between Pluronics and pre-formed 16-3-16/plasmid DNA complexes depends on solution composition but primarily poly(propylene oxide) block length.