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Dynamic strength of molecular adhesion bonds
1Department of Physics, University of British Columbia, Vancouver, Canada. evans@physics.ubc.ca
Biophysical Journal
|April 1, 1997
Summary
Molecular bond strength depends on how quickly it is pulled. This study extends reaction kinetics theory to predict bond rupture forces, showing three distinct loading rate regimes. Brownian dynamics simulations bridge experimental and molecular dynamics time scales.
Area of Science:
- Biophysics
- Molecular Biophysics
- Biochemistry
Background:
- Molecular linkages in biology rely on weak, noncovalent interactions.
- These bonds are susceptible to failure under sustained or applied force.
- Understanding bond strength requires considering time and loading rate dependencies.
Purpose of the Study:
- To extend Kramers' theory to predict molecular bond dissociation under force.
- To investigate the relationship between loading rate and bond strength.
- To bridge the time scale gap between molecular dynamics and experimental force measurements.
Main Methods:
- Extended Kramers' theory for reaction kinetics to model bond rupture.
- Employed smart Monte Carlo (Brownian dynamics) simulations to test theoretical predictions.
- Analyzed rupture force distributions to define bond strength.
- Utilized simulation data of biotin-avidin bonds.
Main Results:
- Bond strength exhibits three dynamic regimes based on loading rate.
- A critical loading rate exists where spontaneous dissociation balances applied force.
- Strength increases with loading rate, following power-law and logarithmic dependencies.
- At ultrafast rates, frictional drag dominates over bonding potential.
Conclusions:
- Molecular adhesion forces are critically dependent on the timescale of observation.
- Brownian dynamics simulations can effectively bridge the gap between molecular dynamics and experimental probe tests.
- Characterizing bond strength requires measurements across a vast range of time scales.