Hard-wall entropic effect accelerates detachment of adsorbed polymer chains

Area of Science:

• Biophysics
• Polymer Physics
• Chemical Kinetics

Background:

• Traditional unbinding kinetics studies often use a two-state model (bonded/free).
• This model may not fully capture complex biopolymer dynamics with multiple reaction pathways.
• Understanding segment-level kinetics is crucial for more accurate biopolymer behavior prediction.

Purpose of the Study:

• To investigate the kinetic rate of polymer unbinding at the segment level.
• To analyze how a growing dangling end influences the detachment rate.
• To develop a model applicable to more complex biopolymer dynamics.

Main Methods:

• Utilized the mean first-passage time approach.
• Modeled the polymer as a chain attached to a wall via spring potentials.
• Incorporated entropic repulsion from the free chain end interacting with the wall.

Main Results:

• Derived the average monomer detachment rate (K) as a function of free dangling length (L).
• Identified an acceleration factor in detachment rate for flexible polymers, dependent on L and bond specifics.
• Observed a similar enhancing factor for semiflexible filaments, with a distinct behavior for rigid rods.

Conclusions:

• The segment-level analysis provides a more nuanced understanding of polymer unbinding kinetics.
• The findings highlight the significant impact of dangling chain length and polymer flexibility on unbinding dynamics.
• The study offers a framework for analyzing complex biopolymer interactions beyond simplified models.