Modifying the surface charge of single track-etched conical nanopores in polyimide

Area of Science:

• Materials Science
• Nanotechnology
• Surface Chemistry

Background:

• Nanopore surface modification is crucial for controlling transport characteristics, particularly for sensor applications.
• Current methods are limited by substrate material, restricting surface composition and biomolecule attachment.
• Controlling nanopore properties is key for developing advanced sensors based on ion and molecule transport.

Purpose of the Study:

• To develop a method for altering the surface charge polarity of single track-etched conical nanopores in polyimide.
• To demonstrate the potential for attaching complex molecules to nanopore walls via carboxyl groups.
• To establish a reversible surface modification process for polyimide nanopores.

Main Methods:

• Chemical conversion of carboxyl groups to terminal amino groups using N-(3-dimethylaminopropyl)-N-ethylcarbodiimide (EDC) and N-hydroxysuccinimide (NHS), followed by ethylenediamine coupling.
• Regeneration of carboxyl-terminated surfaces by reacting amino groups with succinic anhydride.
• Confirmation of surface modification by measuring pH-sensitive current-voltage (I-V) characteristics and permselectivity.

Main Results:

• Successful reversal of surface charge polarity in polyimide nanopores.
• Demonstrated capability to attach molecules to the nanopore surface.
• Confirmed reversibility of the surface modification process.
• Observed changes in pore permselectivity correlating with surface charge modification.

Conclusions:

• The developed chemical modification method effectively alters polyimide nanopore surface charge polarity.
• This technique offers a pathway for attaching biomolecules and tailoring nanopore properties for sensor applications.
• The reversible nature of the modification enhances its utility for diverse nanopore-based technologies.