Layer-by-layer assembly of polyelectrolytes into ionic current rectifying solid-state nanopores: insights from theory...

Area of Science:

• Nanotechnology
• Supramolecular Chemistry
• Physical Chemistry

Background:

• Molecular design of ionic current rectifiers in single conical nanopores is a growing research area.
• Functionalizing pore walls is key to controlling selectivity and transport properties for sensors and nanoactuators.
• Layer-by-layer (LbL) polyelectrolyte deposition offers a method for creating functional supramolecular assemblies in confined geometries.

Purpose of the Study:

• To integrate LbL polyelectrolyte assemblies into single conical nanopores.
• To investigate the functional features of charged supramolecular assemblies within nanofluidic devices.
• To elucidate and quantify electrostatic changes during supramolecular assembly in nanopores.

Main Methods:

• Combined experimental and theoretical approaches were used.
• Multilayered films were created via consecutive LbL adsorption of poly(allylamine hydrochloride) (PAH) and poly(styrenesulfonate) (PSS).
• Charge transport properties and surface charge changes within the nanopore were analyzed.

Main Results:

• The charge transport properties of functionalized nanopores strongly depended on the number of PAH/PSS layers.
• Unlike planar films, nanopore surface charge decreased with increasing PAH/PSS layers.
• Nanoconfinement induced structural reorganization of polyelectrolyte layers, leading to ion pair formation and reduced net charge.

Conclusions:

• LbL polyelectrolyte assemblies can be integrated into single conical nanopores to modify their properties.
• Nanoconfinement significantly influences the structure and charge of polyelectrolyte assemblies, differing from planar systems.
• These findings are relevant for modifying nanopores, nanopipets, and nanoelectrodes for soft nanotechnology applications.