# A model for the contraction kinetics of cytoskeletal gel slabs

Source: [A model for the contraction kinetics of cytoskeletal gel slabs](<https://www.sota2.com/research/paper/68fa445b1e209131ce9108e0>)

Collection index: [llms.txt](<https://www.sota2.com/research/llms.txt>)

Data updated: 2025-10-25T04:44:56.489Z

Authors: Matteo Ferraresso, Mohammad Shojaeifard, Albert Kong, Mattia Bacca

Published: 2023-05-31T13:05:46.000Z

## Abstract

Cytoskeletal gels are engineered prototypes that mimic the contractile behavior of a cell in-vitro. They are composed of an active polymer matrix and a liquid solvent. Their contraction kinetics is governed by two dynamic phenomena: mechanotransduction (molecular motor activation), and solvent diffusion. In this paper, we solve the transient problem for the simple case of a thin gel slab in uniaxial contraction under two extreme conditions: motor-limited or slow motor activation (SM) regime, and diffusion-limited or fast motor activation (FM) regime. The former occurs when diffusion is much faster than mechanotransduction, while the latter occurs in the opposite case. We observe that in the SM regime, the contraction time scales as t/t\_0 ~ (l/l\_0)^(-3), with t\_0 the nominal contraction time, and l and l\_0 are the final and initial stretches of the slab. t\_0 is proportional to 1/w, where w is the average mechanical power generated by the molecular motors per unit reference (dry polymer) volume. In the FM regime, the contraction time scales as t/t\_1 ~ (1-l/l\_0)^2, with t\_1 the nominal contraction time, here proportional to the ratio L^2/D, where L is the reference (dry polymer) thickness, and D is the diffusivity of the solvent in the gel. The transition between the SM and FM regimes is defined by a characteristic power density w^\*, where w \<\< w^\* gives the SM regime and w \>\> w^\* gives the FM regime. Intuitively, w^\* is proportional to D/L^2, where, at a given power density w, a thinner gel slab (smaller L) or including smaller solvent molecules (higher D) is more likely to be in the SM regime given that solvent diffusion will occur faster than motor activation.

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## Original sources and implementation

[Original paper](<https://arxiv.org/abs/2305.19824>)

[PDF](<https://arxiv.org/pdf/2305.19824.pdf>)