Issue |
EPL
Volume 96, Number 3, November 2011
|
|
---|---|---|
Article Number | 36007 | |
Number of page(s) | 6 | |
Section | Condensed Matter: Structural, Mechanical and Thermal Properties | |
DOI | https://doi.org/10.1209/0295-5075/96/36007 | |
Published online | 20 October 2011 |
Filling the void in confined polymer nematics: Phase transitions in a minimal model of dsDNA packing
Department of Polymer Science and Engineering, University of Massachusetts - Amherst, MA 01003, USA
Received:
22
July
2011
Accepted:
16
September
2011
Inspired to understand the complex spectrum of space-filling organizations of the dsDNA genome within the capsid of bacterial viruses, we study a minimal, coarse-grained model of single chains densely packed into a finite spherical volume. We build the three basic elements of the model —i) the absence of chain ends, ii) the tendency of parallel-strand alignment and iii) a preference of uniform areal density of chain segments— into a polymer nematic theory for confined chains. Given the geometric constraints of the problem, we show that axially symmetric packings fall into one of three topologies: the coaxial spool; the simple solenoid; and the twisted solenoid. Among these, only the twisted solenoid fills the volume without the presence of line-like disclinations, or voids, and is therefore generically preferred in the incompressible limit. An analysis of the thermodynamics behavior of this simple model reveals a rich behavior, a generic sequence of phases from the empty state for small container sizes, to the coaxial spool configuration at intermediate sizes, ultimately giving way, via a second-order, symmetry-breaking transition, to the twisted-solenoid structure above a critical sphere size.
PACS: 61.30.Vx – Polymer liquid crystals / 87.14.gk – DNA / 64.70.mf – Theory and modeling of specific liquid crystal transitions, including computer simulation
© EPLA, 2011
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.