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.