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Liquid crystal formation in DNA fragment solutions
Author(s) -
Kassapidou K.,
Jesse W.,
van Dijk J. A. P. P.,
van der Maarel J. R. C.
Publication year - 1998
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/(sici)1097-0282(199807)46:1<31::aid-bip3>3.0.co;2-z
Subject(s) - chemistry , counterion , thermodynamics , ionic bonding , isotropy , excluded volume , persistence length , counterion condensation , debye length , hard spheres , ionic strength , chemical physics , ion , computational chemistry , molecule , aqueous solution , organic chemistry , physics , quantum mechanics , polymer
The critical volume fractions pertaining to the formation of DNA liquid crystals were obtained from polarization microscopy, 31 P‐nmr, and phase separation experiments. The DNA length (approximately one to two times the persistence length 50 nm), ionic strength, and counterion variety dependencies are reported. The cholesteric–isotropic transition is interpreted in terms of the coexistence equations, which are derived from the solution free energy including orientational entropy and excluded volume effects. With the wormlike chain as reference system, the electrostatic contribution to the free energy is evaluated as a thermodynamic perturbation in the second virial approximation with a Debye–Hückel potential of mean force. The hard core contribution has been evaluated with scaled particle theory and/or a simple generalization of the Carnahan–Starling equation of state for hard spheres. For sufficiently high ionic strengths, the agreement is almost quantitative. At lower amounts of added salt deviations are observed, which are tentatively attributed to counterion screening effects. The contour length dependence agrees with a DNA persistence length 50 nm. © 1998 John Wiley & Sons, Inc. Biopoly 46: 31–37, 1998