Adaptive Polyzwitterion Coatings Enable Optimal Ion Rectification in Functionalized Nanochannels.

Area of Science:

• Nanotechnology
• Materials Science
• Physical Chemistry

Background:

• Biological ion channels inspire synthetic nanopores for nanofluidic diodes.
• Conical nanopores face challenges like clogging and complex fabrication.
• Existing synthetic diodes often lack precise control and tunability.

Purpose of the Study:

• To investigate pH-sensitive ion current rectification (ICR) in cylindrical nanochannels.
• To overcome fabrication and operational limitations of conical nanopores.
• To develop a tunable platform for smart ion-based sensors.

Main Methods:

• Utilizing nonuniform grafting of a zwitterionic polyelectrolyte layer in cylindrical nanochannels.
• Investigating ion current rectification (ICR) induced by spatial charge variation.
• Developing a simplified analytical model to predict rectification patterns.

Main Results:

• Achieved pH-sensitive ion rectification in cylindrical nanochannels via zwitterionic polyelectrolyte grafting.
• Identified an optimal polyelectrolyte zwitterionic layer thickness (tPZL) for maximal rectification, challenging previous assumptions.
• Demonstrated pH-dependent tunability of rectification characteristics and diode-like response.

Conclusions:

• Cylindrical nanochannels with nonuniform zwitterionic grafting offer a viable alternative to conical nanopores for nanofluidic diodes.
• The findings provide a versatile platform for pH-responsive ion rectification and smart sensor development.
• The developed analytical model aids in optimizing tPZL for specific operating conditions.