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arXiv · 1702.00878

Heterogeneous morphology and dynamics of polyelectrolyte brush condensates in trivalent counterion solution

Lei Liu·Philip A. Pincus·Changbong Hyeon
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Abstract

Recent experiments have shown that trivalent ion, spermidine$^{3+}$, can provoke lateral microphase segregation in DNA brushes. Using molecular simulations and simple theoretical arguments, we explore the effects of trivalent counterions on polyelectrolyte brushes. At a proper range of grafting density, polymer size, and ion concentration, the brush polymers collapse heterogeneously into octopus-like surface micelles. Remarkably, the heterogeneity in brush morphology is maximized and the relaxation dynamics of chain and condensed ion are the slowest at the 1:3 stoichiometric concentration of trivalent ions to polyelectrolyte charge. A further increase of trivalent ion concentration conducive to a charge inversion elicits modest reswelling and homogenizes the morphology of brush condensate. Our study provides a new insight into the origin of the diversity in DNA organization in cell nuclei as well as the ion-dependent morphological variation in polyelectrolyte brush layer of biological membranes.

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Lei Liu, Philip A. Pincus, Changbong Hyeon. 2017-02-03. Heterogeneous morphology and dynamics of polyelectrolyte brush condensates in trivalent counterion solution. https://doi.org/10.1021/acs.macromol.6b02685

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