Regensburg 2022 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 12: Poster 1

CPP 12.12: Poster

Montag, 5. September 2022, 18:00–20:00, P1

Controlling the phase transitions in surfactant-dna complexes — A.V. Radhakrishnan^1,2, S. Madhukar¹, A. Chowdhury¹, and •V.A. Raghunathan¹ — ¹Raman Research Institute Bangalore 560080 India — ²Experimental Physics I, University of Bayreuth, Bayreuth 95447 Germany

Surfactant-DNA complexes are a special class of polyelectrolyte complexes where one of the macroions is formed by self assembly. They have been studied for their interesting electrostatics and potential applications for gene delivery and photonic applications. The gain in counter ion entropy is driving the complex formation and there is an interesting interplay of electrostatics and entropy leading to a rich phase behavior. The self assembled macroion can be formed either by a bilayer forming lipid or a micelle forming surfactant. We have studied the structural transitions in complexes formed by cationic surfactants such as CTAB, CTAT, DTAB with ds-DNA and constructed phase diagrams. Using small angle xray scattering and polarizing optical microscopy and elemental analysis the presence of a various phases, including a square phase(S), hexagonal phase (H) and a hexagonal super lattice phase (Hs) are identified. Detailed modeling of these structures have been carried out based on the electron density maps to propose the packaging of the macroions in the lattices. Striking differences in the phase diagrams and various ways of controlling the structural transitions will be discussed.