Liquid crystals (LCs) ordering of DNA and RNA oligomers relies on the presence of inter-duplex end-to-end attraction, driving the formation of linear aggregates. Such interactions are gauged, at a macroscopic level, by the osmotic pressure at the isotropic-nematic and nematic-columnar phase transitions. We studied aqueous solutions of PEG and DNA duplex-forming oligomers, finding that there is a wide range of concentrations in which these mixtures phase separate into coexisting PEG-rich and DNA-rich phases, the latter being either in the isotropic state or ordered as a nematic or columnar LC. We determined the phase diagram in mixtures of PEG and DNA duplexes with different terminal motifs–blunt ends, sticky overhangs, aggregation-preventing overhangs–and measured the partitioning of the species in the coexisting phases. On this basis, we determined the osmotic pressure as a function of the DNA concentration across the phase diagram. We compared the equation of state obtained in this way with both the Carnahan–Starling equation of state for hard spheres and with the pressure predicted by computer simulations of a system of aggregating cylinders. We obtain a good agreement between experiments and simulations, and end-to-end attraction energies of the order of 6 kcal/mol, a bit larger than expected, but still in agreement with the current models for DNA-DNA interactions.

Phase separations, liquid crystal ordering and molecular partitioning in mixtures of PEG and DNA oligomers / S. Di Leo, M. Todisco, T. Bellini, T.P. Fraccia. - In: LIQUID CRYSTALS. - ISSN 0267-8292. - 45:13-15(2018 Dec), pp. 2306-2318. [10.1080/02678292.2018.1519123]

Phase separations, liquid crystal ordering and molecular partitioning in mixtures of PEG and DNA oligomers

S. DI LEO;M. Todisco;T. Bellini
;
T.P. Fraccia
2018

Abstract

Liquid crystals (LCs) ordering of DNA and RNA oligomers relies on the presence of inter-duplex end-to-end attraction, driving the formation of linear aggregates. Such interactions are gauged, at a macroscopic level, by the osmotic pressure at the isotropic-nematic and nematic-columnar phase transitions. We studied aqueous solutions of PEG and DNA duplex-forming oligomers, finding that there is a wide range of concentrations in which these mixtures phase separate into coexisting PEG-rich and DNA-rich phases, the latter being either in the isotropic state or ordered as a nematic or columnar LC. We determined the phase diagram in mixtures of PEG and DNA duplexes with different terminal motifs–blunt ends, sticky overhangs, aggregation-preventing overhangs–and measured the partitioning of the species in the coexisting phases. On this basis, we determined the osmotic pressure as a function of the DNA concentration across the phase diagram. We compared the equation of state obtained in this way with both the Carnahan–Starling equation of state for hard spheres and with the pressure predicted by computer simulations of a system of aggregating cylinders. We obtain a good agreement between experiments and simulations, and end-to-end attraction energies of the order of 6 kcal/mol, a bit larger than expected, but still in agreement with the current models for DNA-DNA interactions.
aqueous two-phase systems; DNA osmotic pressure; DNA self-assembly; equation of state; Liquid crystals; PEG-DNA phase separation; Chemistry (all); Materials Science (all); Condensed Matter Physics
Settore FIS/07 - Fisica Applicata(Beni Culturali, Ambientali, Biol.e Medicin)
Settore FIS/01 - Fisica Sperimentale
dic-2018
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/627319
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