Promoting single-file DNA translocations through nanopores using electro-osmotic flow

Area of Science:

• Nanotechnology
• Biophysics
• Molecular Biology

Background:

• Double-stranded DNA (dsDNA) can translocate through nanopores linearly or in a folded hairpin state.
• Understanding and controlling DNA conformation within nanopores is crucial for advanced sensing applications.

Purpose of the Study:

• To investigate methods for controlling the folding state of DNA during nanopore translocation.
• To explore the impact of buffer conditions on DNA translocation behavior.

Main Methods:

• Experimentally manipulating electrolyte concentration, pH, and polyethylene glycol (PEG) content in the measurement buffer.
• Observing and analyzing DNA translocation events through nanopores under varying conditions.
• Utilizing electro-osmotic flow (EOF) as a key factor influencing DNA conformation.

Main Results:

• DNA folding state is controllable by adjusting buffer parameters.
• At pH 8 in 1M LiCl or 0.35M KCl, over 90% of translocations were single-file.
• Electro-osmotic flow at low ionic strength is identified as a critical factor driving the observed folding control.
• Experimental evidence supports the role of flow, showing preferred entry orientation for folded DNA.

Conclusions:

• Buffer composition significantly influences DNA folding and translocation dynamics in nanopores.
• Electro-osmotic flow plays a critical role in directing DNA conformation during nanopore experiments.
• Precise control over DNA folding is achievable and essential for developing sophisticated nanopore-based sensing platforms.