Charge-controlled permeability of polyelectrolyte microcapsules.

Area of Science:

• Materials Science
• Nanotechnology
• Physical Chemistry

Background:

• Multilayer microcapsules offer tunable properties for various applications.
• Controlling permeability at the nanoscale is crucial for targeted delivery and separation.
• Previous methods lacked precise charge-dependent control over microcapsule permeability.

Purpose of the Study:

• To fabricate multilayer microcapsules with unique charge-controlled permeability.
• To investigate the role of poly(styrene sulfonate) (PSS) in dictating capsule properties.
• To demonstrate the selective transport capabilities of the fabricated microcapsules.

Main Methods:

• Fabrication of multilayer microcapsules using poly(styrene sulfonate) (PSS)-doped CaCO3 particles as templates.
• Characterization using Scanning Force Microscopy (SFM), UV-vis, Raman spectroscopy, and zeta-potential measurements.
• Permeability studies using fluorescently labeled dextrans (FITC-dextran, TRITC-dextran) and proteins (albumin) with confocal microscopy.

Main Results:

• Successful fabrication of multilayer microcapsules with encapsulated PSS molecules after core removal.
• Demonstrated charge-controlled permeability: complete rejection of negatively charged probes and attraction of positively charged species.
• Switchable permeation for proteins and dyes by altering probe charge (pH) or reducing repulsion (salt addition).

Conclusions:

• The developed microcapsules exhibit highly sensitive, charge-tunable permeability.
• The structure allows for selective encapsulation and controlled release based on probe charge.
• These findings present a promising platform for advanced separation, sensing, and controlled delivery systems.