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Varga Imre

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Fehér Bence
Modelling of small-angle scattering data on the absolute scale: investigation of model system NaPSS/DTAB and potentials for structural biophysics applications

Aug 29 - kedd

12:00 – 12:15

Modern biofizikai módszerek

E12

Modelling of small-angle scattering data on the absolute scale: investigation of model system NaPSS / DTAB and potentials for structural biophysics applications

Bence Fehér1,2, Attila Bóta3 , András Wacha3, Bálint Jezsó3, Jan Skov Pedersen2 and Imre Varga4,5

1 Laboratory of Self-Organizing Soft Matter, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands

2 Department of Chemistry and Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Gustav Wieds Vej 14, 8000 Aarhus C, Denmark

3 Research Centre for Natural Sciences, Institute of Materials and Environmental Chemistry, Magyar tudósok körútja 2, 1117 Budapest, Hungary

4 Institute of Chemistry, Eötvös Loránd University, Pázmány Péter sétány 1/A, 1117 Budapest, Hungary5

4 Department of Chemistry, University J. Selyeho, 945 01 Komárno, Slovakia

Polyelectrolyte / surfactant (P/S) complexes are important model systems of biologically relevant complexes such as DNA, RNA, protein / surfactant complexes. Due to the structural complexity of biologically relevant polyelectrolytes they are often modelled by synthetic polyelectrolytes in order to investigate the fundamental thermodynamics of the system. There are several studies aiming at describing the structural and phase properties of P/S systems. In the phase-separation region, examples of hexagonal, lamellar, and cubic structure have been identified. At the same time, there is little information about the structure of the complexes in the one-phase region and only a few studies were published dealing with the effect of surfactant concentration on the morphology of P/S aggregates.

In our study we prepared PSS/DTAB samples in the equilibrium and phase separation range. Since in the recent decades it has been clearly shown that the high charge density P/S mixtures are prone for the formation of kinetically arrested non-equilibrium aggregates, we used a novel sample preparation method to facilitate the formation of the equilibrium non-aggregated P/S complexes in the entire investigated surfactant concentration range. We measured the binding isotherm and simultaneously we performed small-angle X-ray scattering measurements and performed data modelling with least-square fitting method on absolute scale. We showed that by increasing the binding ratio the formed complexes exhibit an elongated to spherical transition which ends with well-defined 3 dimensional hexagonal precipitate with spherical particles in the crystal points. We also showed that the addition of indifferent electrolyte (NaCl) changes the structural behavior of the system and yields amorphous structure. Summarizing, first in the literature we connected the binding isotherm to the structural features of complexes in the equilibrium and phase separation regime.

Acknowledgment

This research received funding from the Hungarian National Research, Development and Innovation Office (NKFIH K116629), which is gratefully acknowledged. This publication was also supported by the Operational Programme Research and Innovation for the project: “Support of research and development capacities in the area of nanochemical and supramolecular systems”, code ITMS2014 + 313011T583, funded from the resources of the European Regional Development Fund.