Note: Direct force and ionic-current measurements on DNA in a nanocapillary.

Area of Science:

• Biophysics
• Nanotechnology
• Molecular Biology

Background:

• Nanocapillaries serve as single-molecule biosensors analogous to solid-state nanopores.
• Analyzing DNA translocation is crucial for understanding molecular interactions and developing biosensing technologies.

Purpose of the Study:

• To develop and demonstrate a novel experimental setup for analyzing DNA translocation through nanocapillaries.
• To enable simultaneous measurement of ionic current and electrophoretic forces acting on DNA during translocation.

Main Methods:

• Utilized optical tweezers with force measurements derived from fast video tracking.
• Employed a novel experimental configuration orienting the nanocapillary perpendicular to the trapping laser.
• Performed real-time, sub-millisecond resolution position tracking of DNA-coated colloids using video analysis.

Main Results:

• Achieved real-time, high-resolution tracking of DNA-coated colloids.
• Successfully performed simultaneous ionic-current and electrophoretic force measurements of single DNA molecules.
• Demonstrated the capability to analyze DNA translocation dynamics within a nanocapillary.

Conclusions:

• The developed optical tweezers system provides a powerful tool for analyzing DNA translocation through nanocapillaries.
• This method allows for precise control and detailed characterization of single DNA molecules in biosensing applications.
• Represents a significant step forward in the study of DNA-nanopore interactions and biosensor development.