2003/07/16 by Ken Sekimoto, Sekimoto, Ken, Jacques Prost +8
Biochemistry, Genetics and Molecular Biology · Engineering · Physics and Astronomy · #Advanced Materials and Mechanics #Biological Physics (physics.bio-ph) #Cellular Mechanics and Interactions #Chemical Physics (physics.chem-ph) #FOS: Physical sciences #Hydrogels: synthesis, properties, applications #physics.bio-ph #physics.chem-ph
paper · pdf · doi:10.48550/arxiv.physics/0307077
21 pages' text and 8 figures
arxiv created 2003/07/16 · openalex publication_date 2003/07/16 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
It has been observed experimentally that the actin gel grown from spherical beads coated with polymerization enzymes spontaneously breaks the symmetry of its spherical shape, and yields a ``comet'' pushing the bead forward. We propose a mechano-chemical coupling mechanism for the initialization of this symmetry breaking. Key assumptions are that the dissociation of the gel takes place mostly in the region of the external surface, and that the rates of the dissociation depends on the tensile stress in the gel. We analyze a simplified two-dimensional model with a circular substrate. Our analysis shows that the symmetric steady state is always unstable against the inhomogeneous modulation of the thickness of the gel layer, for any radius of the circular substrate. We argue that this model represents the essential feature of the three-dimensional systems for a certain range of characteristic lengths of the modulation. The characteristic time of the symmetry breaking process in our model depends linearly on the radius of curvature of the substrate surface, which is consistent with experimental results, using spherical latex beads as substrate. Our analysis of the symmetry breaking phenomenon demonstrates aspects of mechano-chemical couplings that should be working in vivo as well as in vitro.