Interaction between DNA and cationic diester-bonded Gemini surfactants

Abstract

The formation of the polyion-complex between three cationic diester-bonded Gemini surfactants and DNA has been demonstrated systematically. This was studied through the electrostatic attraction between ammonium head groups of Gemini surfactants and the phosphate groups of DNA. Ethidium bromide exclusion assay indicates the interaction between DNA and diester-bonded Gemini surfactants. DNA binding abilities with the Gemini surfactant depends on tail length which has been demonstrated by agarose gel electrophoresis and circular dichroism (CD) measurements. Dynamic light scattering measurements reveal that the ester-bonded Gemini surfactants can induce the collapse of DNA into densely packed bead-like structures with smaller size. Molecular docking technique was also utilized to understand the mode and mechanism of interaction between DNA and the Gemini surfactants (pre-micellar form). In addition to electrostatic interactions between the negatively charged phosphate backbone of DNA and positively charged head groups of Gemini surfactants, self-association due to hydrophobic interactions between the alkyl tails of surfactant and the hydrogen bonding between the ester group of surfactant and nucleotide bases, result in the compaction of nucleotides.