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Please use this identifier to cite or link to this item: http://hdl.handle.net/2289/7976
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dc.contributor.authorRadhakrishnan, A.V.-
dc.contributor.authorMadhukar, S.-
dc.contributor.authorChowdhury, A.-
dc.contributor.authorRaghunathan, V.A.-
dc.date.accessioned2022-07-25T05:22:07Z-
dc.date.available2022-07-25T05:22:07Z-
dc.date.issued2022-06-24-
dc.identifier.citationPhysical Review E, 2022, Vol.105, p064504en_US
dc.identifier.issn2470-0053 (Online)-
dc.identifier.issn2470-0045-
dc.identifier.urihttp://hdl.handle.net/2289/7976-
dc.descriptionRestricted Access.en_US
dc.description.abstractWe have studied the structure of complexes of the cationic surfactant dodecyltrimethylammonium bromide (DTAB) with DNA as a function of surfactant to DNA base molar ratio (R) and salt concentration. Small-angle x-ray scattering data show the formation of nematic gels at lower and higher salt concentrations, irrespective of the value of R. Two crystalline phases are observed over intermediate salt concentrations; a square (S) phase for R>3 and a hexagonal (HS) phase for lower R. Electron density maps of these phases show intercalated structures, with DTAB micelles sandwiched between long DNA strands. The composition of these complexes, estimated using elemental analysis, indicates that the micelles are not very long, and they occupy only about half of the interstitial volume between the DNA strands. This phase behavior is strikingly different from that of complexes of DNA with longer chain surfactants cetyltrimethylammonium bromide (CTAB) and tetradecyltrimethylammonium bromide (TTAB), which show only a hexagonal (H) phase over similar ranges of R and salt concentration, the HS structure observed in the present study being a √3×√3 superlattice of the H structure. Madelung energies of the S and H structures, calculated from the electrostatic interaction between their cylindrical constituents, suggest that the former is preferred in DTAB-DNA complexes due to the smaller micellar radius of DTAB. The propensity of DTAB to form short micelles seems also to favor the HS phase at lower R. These results illustrate the important role of micellar size in determining the structure of these two-dimensional macro-ion crystals.en_US
dc.language.isoenen_US
dc.publisherAmerican Physical Societyen_US
dc.relation.urihttps://doi.org/10.1103/PhysRevE.105.064504en_US
dc.rights2022 American Physical Societyen_US
dc.subjectphase diagramsen_US
dc.subjectphase transitionsen_US
dc.subjectcolumnar liquid crystalsen_US
dc.subjectpolyelectrolytesen_US
dc.titleInfluence of micellar size on the structure of surfactant-DNA complexesen_US
dc.typeArticleen_US
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