Electrophoretic collision of a DNA molecule with an insulating post

Area of Science:

• Biophysics
• Polymer Physics
• Microfluidics

Background:

• Understanding DNA dynamics is crucial for molecular biology and nanotechnology.
• Electric fields are used to manipulate charged molecules like DNA.
• Interactions between DNA and obstacles are fundamental to DNA behavior in confined environments.

Purpose of the Study:

• To investigate the dynamics of single DNA molecules interacting with a stationary obstacle under an electric field.
• To determine the factors influencing the probability of DNA "hooking" events.
• To analyze the role of electric field gradients and polymer configuration sensitivity.

Main Methods:

• Simulating single DNA molecule trajectories driven by an electric field towards a stationary obstacle.
• Classifying collision outcomes into "hook" and "roll-off" events.
• Analyzing the influence of electric field gradients and Deborah number (De) on DNA-obstacle interactions.

Main Results:

• Obstacle-induced electric field gradients cause significant stretching of impacting DNA molecules.
• The probability of a "hook" event is strongly influenced by DNA stretching, collision geometry, and the Deborah number (0.5 < De < 40).
• Individual DNA impact dynamics exhibit high configuration sensitivity, consistent with polymer behavior in elongational flows.

Conclusions:

• Electric field gradients are a critical factor in determining DNA-obstacle collision outcomes.
• The Deborah number provides a quantitative measure for predicting hooking probability in this dynamic system.
• DNA's behavior in electric fields near obstacles is complex and highly dependent on its conformation and the flow conditions.