Self-assembled aggregates in the gravitational field: growth and nematic order

TL;DR

This paper investigates how gravitational fields influence the assembly, growth, and phase transitions of linear biological aggregates like microtubules, revealing gravity-induced growth and phase behavior changes.

Contribution

It provides a theoretical analysis of gravity's effect on aggregate assembly, growth, and phase transitions, extending understanding to biological systems under gravitational influence.

Findings

Gravity causes concentration gradients affecting aggregate distribution.

Strong gravity induces aggregate growth and broadens phase transition regions.

Ultracentrifuge fields amplify gravitational effects on phase behavior.

Abstract

The influence of the gravitational field on the reversible process of assembly and disassembly of linear aggregates is focus of this paper. Even the earth gravitational field can affect the equilibrium properties of heavy biological aggregates such as microtubules or actin filaments. The gravity gives rise to the concentration gradient which results in the distribution of aggregates of different lengths with height. Strong enough gravitational field induces the overall growth of the aggregates. The gravitational field facilitates the isotropic to nematic phase transition reflecting in a broader transition region. Coexisting phases have notedly different length distributions and the phase transition represent the interplay between the growth in the isotropic phase and the precipitation into nematic phase. The fields in an ultracentrifuge can only reinforce the effect of gravity, so the present description can be applied to a wider range of systems.