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Super-helical filaments at surfaces: dynamics and elastic responses
Min-Kyung Chae1, Yunha Kim1, Albert Johner2
1Department of Physics, Sejong University, Seoul 05006, South Korea. lee@sejong.ac.kr.
Soft Matter
|March 3, 2018
Summary
Bio-filaments exhibit complex behaviors beyond standard models when confined. Simulations reveal long-lived excited states and shape changes under tension, crucial for understanding their dynamics.
Area of Science:
- Biophysics
- Polymer Physics
- Soft Matter Science
Background:
- Standard semi-flexible polymer chain models (WLC) fail to explain bio-filament behavior under confinement or tension.
- A super-helical filament model, accounting for wider helical structures, is necessary to describe these deviations.
- Understanding bio-filament mechanics is vital for cellular processes and biomaterial design.
Purpose of the Study:
- To investigate the behavior of bio-filaments using the super-helical filament model under confinement.
- To analyze the impact of tension on filament shapes and shape fluctuations, including excited states.
- To explore the dynamics of twist-kink formation, diffusion, and relaxation mechanisms.
Main Methods:
- Brownian dynamics simulations of the super-helical filament model.
- Focus on filaments confined to a surface by a strong potential.
- Analysis of shapes, shape fluctuations, and dynamic responses under varying tension.
Main Results:
- Excited states with multiple inflection points (twist-kinks) can be stabilized under tension.
- Hysteresis observed in pulling/releasing experiments indicates memory effects.
- The lifetime of excited states increases cubically with filament length, and twist-kink diffusion exhibits position-dependent friction.
Conclusions:
- The super-helical filament model accurately captures complex bio-filament behaviors not explained by WLC.
- Tension-induced excited states are long-lived and exhibit unique dynamic properties.
- Analytical expressions for twist-kink diffusion and rationalized shape relaxation mechanisms provide new insights into bio-filament mechanics.
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