Shape and stability of two-dimensional lipid domains with dipole-dipole interactions

Department of Physical Electronics, Tokyo Institute of Technology, Meguro-ku, Tokyo 152-8552, Japan.
The Journal of Chemical Physics (Impact Factor: 2.95). 01/2007; 125(22):224701. DOI: 10.1063/1.2402160
Source: PubMed


We study the general energy and shape of the two-dimensional solid monolayer domains with the dipole-dipole interactions. Compared with the domain energy without tilted dipole moments [M. Iwamoto and Z. C. Ou-Yang, Phys. Rev. Lett. 93, 206101 (2004)], the general dipolar energy is not only shape and size but also boundary orientation dependent. The general shape equation derived by this energy using variational approach predicts a circular solution and an equilibrium shape grown from this circle. In particular, the latter is composed of two branches: a translation-induced growth of all odd harmonic modes and a pressure-induced cooperative deformation by all even harmonic modes. The good qualitative agreement between our prediction and the experimental observations shows the validity of the present theory.

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    • "where N is the normal vector at x and H is the mean curvature. High-order curvatures have been extensively studied in the context of membrane bending analysis (Canham, 1970; Helfrich, 1973; Ou-Yang and Helfrich, 1989; Iwamoto et al., 2006). "
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    • "Interestingly, complex shaped finite size domains of size L, in addition to undulating phases with lamellar and hexagonal ordering, were observed [8] [9] [12] [15] [2] [18] [19] [20] [21] [22]. The observed finite size domains in these systems have been shown to be due to competing interactions, especially short-range steric, chemical mismatches and long-range dipolar interactions [23] [24]. "
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