TY - JOUR A1 - Moradi, N. A1 - Zakrevskyy, Yuriy A1 - Javadi, A. A1 - Aksenenko, E. V. A1 - Fainerman, V. B. A1 - Lomadze, Nino A1 - Santer, Svetlana A1 - Miller, R. T1 - Surface tension and dilation rheology of DNA solutions in mixtures with azobenzene-containing cationic surfactant JF - Colloids and surfaces : an international journal devoted to the principles and applications of colloid and interface science ; A, Physicochemical and engineering aspects N2 - The surface tension and dilational surface visco-elasticity of the individual solutions of the biopolymer DNA and the azobenzene-containing cationic surfactant AzoTAB, as well as their mixtures were measured using the drop profile analysis tensiometry. The negatively charged DNA molecules form complexes with the cationic surfactant AzoTAB. Mixed DNA + AzoTAB solutions exhibit high surface activity and surface layer elasticity. Extremes in the dependence of these characteristics on the AzoTAB concentration exist within the concentration range of 3 x 10(-6)-5 x 10(-5) M. The surface tension of the mixture shows a minimum with a subsequent maximum. In the same concentration range the elasticity shows first a maximum and then a subsequent minimum. A recently developed thermodynamic model was modified to account for the dependence of the adsorption equilibrium constant of the adsorbed complex on the cationic surfactant concentration. This modified theory shows good agreement with the experimental data both for the surface tension and the elasticity values over the entire range of studied AzoTAB concentrations. (C) 2016 Elsevier B.V. All rights reserved. KW - Mixed adsorption layers KW - Polymer/surfactant interaction KW - Water/air interface KW - Thermodynamics of adsorption KW - Dilational rheology KW - Drop profile analysis tensiometry Y1 - 2016 U6 - https://doi.org/10.1016/j.colsurfa.2016.04.021 SN - 0927-7757 SN - 1873-4359 VL - 505 SP - 186 EP - 192 PB - Elsevier CY - Amsterdam ER -