Electro-osmotic Flow Generation via a Sticky Ion Action

Area of Science:

• Nanotechnology
• Biophysics
• Electrochemistry

Background:

• Selective ion transport through nanopores is crucial for biological functions and technologies like water desalination and energy storage.
• Current methods for achieving ion selectivity in nanopores are often pore-specific and require custom approaches.

Purpose of the Study:

• To develop a general method for creating highly selective, anion-conducting nanopores with a giant electro-osmotic effect.
• To investigate the mechanism of ion selectivity and electro-osmotic flow induced by guanidinium ions in various nanopore types.

Main Methods:

• Molecular dynamics simulations were employed to study ion binding and transport.
• Reverse potential measurements were used to experimentally validate the findings.
• Four different biological nanopores and solid-state nanopores were analyzed.

Main Results:

• Exposure to guanidinium chloride solutions resulted in positively charged nanopore surfaces due to transient cation binding.
• This mechanism induced significant anion selectivity and a giant electro-osmotic effect in both biological and solid-state nanopores.
• A correlation was established between ion selectivity, nanopore geometry, surface composition, and electro-osmotic flow.

Conclusions:

• The 'sticky-ion' approach offers a versatile method for controlling ion transport and generating electro-osmotic flow in nanoscale pores.
• This technique has potential applications in molecular transport control, detection, identification, and sequencing of individual proteins.