Long charged macromolecule in an entropic trap with rough surfaces.

Area of Science:

• Physics
• Physical Chemistry
• Biophysics

Background:

• Charged macromolecules, such as double-stranded DNA (dsDNA), are fundamental in biological systems.
• Understanding macromolecular transport through confined geometries is crucial for applications in nanotechnology and biotechnology.
• External electric fields significantly influence the behavior of charged macromolecules.

Purpose of the Study:

• To analytically investigate the kinetics of charged macromolecule flux through an entropic trap.
• To model the behavior of a wormlike chain macromolecule (dsDNA) in a device with alternating wide and constricted regions.
• To determine the free energy landscape and analyze the escape kinetics and scaling behavior of the macromolecule.

Main Methods:

• Utilizing the wormlike chain model for macromolecule representation.
• Accurately calculating chain entropy in deep and shallow slits.
• Accounting for work done by the electric field and elastic bending energy.
• Analyzing the free energy to study escape kinetics and scaling.

Main Results:

• The escape process from the entropic trap is characterized by two distinct kinetic stages.
• Each stage exhibits different time scales, indicating complex transport dynamics.
• The model provides insights into the influence of geometric confinement and electric fields on macromolecule flux.

Conclusions:

• The proposed analytical model accurately describes the kinetics of charged macromolecule transport in entropic traps.
• The two-stage escape mechanism highlights the importance of geometric variations and electrostatic forces.
• Further research can explore the impact of surface roughness on these transport dynamics.