DNA adsorption and rele
ase from cat-anionic vesicles made of sodium dodecylsulfate-dodecyldimethylammoniumbromide (SDS-DDAB) in nonstoichiometric amounts w
as investigated by different electrochemical, s
pectroscopic,and biomolecular strategies. The characterization of the vesicular system w
as performed by dynamic light scattering,which allowed estimating both its size and distribution function(s). The interaction dynamics w
as followed by dielectrics
pectroscopy and
-potential,
as well
as by agarose gel electrophoresis, AGE. Also, circular dichroism, CD, me
asurementswere carried out, to
ascertain possible structural rearrangements of DNA, consequent to the interactions with thecat-anionic vesicles. CD demonstrates that vesicle-bound DNA retains its native conformation. The results obtainedby the aforementioned techniques are consistent and indicate that binding saturation is obtained at a [DNA/vesicles]charge ratio close to 0.8, considering only the excess surface charges on the vesicles. This result is apparently incontradiction with a purely electrostatic approach and is tentatively
ascribed to the distance between charges on thebiopolymer and the vesicle surface, res
pectively. A possible interpretation is discussed. The nucleic acid can becompletely retrieved from the vesicles upon addition of adequate amounts of SDS, which is the defective surfactantin the vesicular system. Precipitation of the poorly soluble SD-DDA salt results in an almost complete rele
ase ofDNA.