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A Novel Platform for In Vitro Cellular Stretching and Imaging
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A toy model of polymer stretching
Carlo Guardiani1, Franco Bagnoli
1Centro Interdipartimentale per lo Studio di Dinamiche Complesse (CSDC), Università di Firenze, Via Sansone I, I-50019 Sesto Fiorentino, Florence, Italy. carlo.guardiani@unifi.it
The Journal of Chemical Physics
|September 13, 2006
Summary
We developed a simplified polymer stretching model that reproduces experimental force-extension profiles. Finite pulling speeds cause increased unfolding forces, matching experimental logarithmic laws.
Area of Science:
- Polymer Physics
- Biophysics
- Computational Modeling
Background:
- Atomic Force Microscopy (AFM) is crucial for probing single-molecule mechanics.
- Polymer stretching experiments exhibit complex force-extension profiles, often showing sawtooth patterns.
- Understanding the underlying physics of polymer unfolding is essential for various applications.
Purpose of the Study:
- To develop a simplified model for polymer stretching in AFM experiments.
- To investigate the relationship between model parameters and experimental observations.
- To elucidate the origins of force peaks and their dependence on pulling speed.
Main Methods:
- A simplified model representing polymer domains as binary contacts.
- Decomposition of system energy into cantilever (harmonic) and intra-domain (long-range) terms.
- Utilizing exact equilibrium computations and Monte Carlo simulations.
Main Results:
- Qualitative reproduction of experimental sawtooth force-extension profiles.
- Identification of these profiles with first-order phase transitions in the model.
- Demonstration that increased force peak heights are an out-of-equilibrium effect due to finite pulling speed.
Conclusions:
- The simplified model captures essential physics of polymer stretching.
- Finite pulling speed is critical for understanding increasing unfolding forces.
- The model successfully reproduces the experimentally observed logarithmic dependence of unfolding force on pulling speed.
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