Ionic current modulation from DNA translocation through nanopores under high ionic strength and concentration...

Area of Science:

• Nanopore science
• Biophysics
• Electrochemistry

Background:

• Ion transport through nanopores is crucial for biological processes and technological applications.
• Previous studies primarily focused on low electrolyte concentrations, limiting understanding under physiological or high-concentration conditions.

Purpose of the Study:

• To investigate ionic current modulation during double-stranded DNA (dsDNA) translocation through nanopores under high ionic strength and concentration gradients.
• To explain the mechanisms behind unexpected positive current modulations observed in these conditions.

Main Methods:

• Experimental measurements of ionic current during dsDNA translocation.
• Numerical simulations of ion transport and fluid dynamics.
• Systematic variation of nanopore diameter and electrolyte concentration gradients.

Main Results:

• dsDNA translocation under high ionic strength and concentration gradients can induce both negative and positive ionic current modulations.
• Positive current pulses, contrary to expectations, were observed.
• Enhanced electroosmotic flow (EOF) driven by negatively charged dsDNA was identified as the cause of positive pulses by transporting additional ions.

Conclusions:

• The study reveals complex ion dynamics during dsDNA nanopore translocation under challenging conditions.
• Enhanced EOF plays a significant role in modulating ionic current, leading to positive pulses.
• Findings advance the understanding of nanopore-based sensing and manipulation technologies.