title: Complexation of DNA with cationic gemini surfactant in aqueous solution.
abstract: Interactions between DNA and the cationic gemini surfactant trimethylene-1,3-bis(dodecyldimethylammonium bromide) (12-3-12) in aqueous solution have been investigated by UV-vis transmittance, zeta potential, and fluorescence emission spectrum. Complexes of DNA and gemini surfactant are observed in which the negative charges of DNA are neutralized by cationic surfactants effectively. The DNA-induced micelle-like structure of the surfactant due to the electrostatic and hydrophobic interactions is determined by the fluorescence spectrum of pyrene. It is found that the critical aggregation concentration (CAC) for DNA/12-3-12 complexes depends little on the addition of sodium bromide (NaBr) because of the counterbalance salt effect. However, at high surfactant concentration, NaBr facilitates the formation of larger DNA/surfactant aggregates. Displacement of ethidium bromide (EB) by surfactant evidently illustrates the strong cooperative binding between surfactant and DNA. In contrast to that in the absence of surfactant, the added NaBr at high surfactant concentration influences not only the binding of surfactant with DNA, but also the stability of DNA/EB complex.
authors.affiliation: The State Key Laboratory of Chemical Engineering and Department of Chemistry, East China University of Science and Technology, Shanghai 200237, China.
authors.forename: Xiaofang
authors.initials: X
authors.lastname: Zhao
authors.forename: Yazhuo
authors.initials: Y
authors.lastname: Shang
authors.forename: Honglai
authors.initials: H
authors.lastname: Liu
authors.forename: Ying
authors.initials: Y
authors.lastname: Hu
mesh_terms: D001965:Bromides / Q000737:chemistry; D002412:Cations / Q000737:chemistry*; D002627:Chemistry, Physical / Q000379:methods; D004247:DNA / Q000737:chemistry*; D004996:Ethidium / Q000737:chemistry; D007477:Ions; D008823:Micelles; D017670:Sodium Compounds / Q000737:chemistry; D013050:Spectrometry, Fluorescence; D013053:Spectrophotometry; D013056:Spectrophotometry, Ultraviolet; D055672:Static Electricity; D013501:Surface-Active Agents / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
chemical_list: D001965:Bromides; D002412:Cations; D007477:Ions; D008823:Micelles; D017670:Sodium Compounds; D013501:Surface-Active Agents; D014867:Water; D004247:DNA; D004996:Ethidium; C027938:sodium bromide