Permeation of macromolecules into polyelectrolyte microcapsules.

Area of Science:

• Materials Science
• Biomaterials Engineering
• Colloid and Surface Chemistry

Background:

• Polyelectrolyte microcapsules (PEMCs) offer versatile platforms for encapsulation and controlled release.
• Red blood cells (RBCs) can serve as sacrificial cores for fabricating biocompatible PEMCs.
• Understanding PEMC permeability is crucial for applications in drug delivery and diagnostics.

Purpose of the Study:

• To investigate the permeability of RBC-templated PEMCs for human serum albumin (HSA).
• To determine the influence of ionic strength and pH on PEMC permeability.
• To elucidate the underlying mechanism governing PEMC permeability.

Main Methods:

• PEMCs were fabricated using layer-by-layer assembly with poly(styrenesulfonate), poly(allylamine hydrochloride), and dextran sulfate on RBC cores.
• Confocal microscopy was employed to quantify HSA permeability across PEMC membranes.
• HSA adsorption onto PEMC walls was correlated with observed permeation rates.

Main Results:

• PEMCs exhibited significantly enhanced HSA permeability at salt concentrations above 1 mM (dextran sulfate/poly(allylamine hydrochloride)) or 5 mM (poly(styrenesulfonate)/poly(allylamine hydrochloride)).
• No significant pH dependence was observed for HSA permeation.
• Permeability correlated with HSA adsorption, suggesting a mechanism involving electrostatic interactions and pore formation.

Conclusions:

• Ionic strength is a critical factor controlling PEMC permeability for HSA.
• The permeability mechanism involves a combination of electrostatic interactions and the presence of pores within the polyelectrolyte layers.
• PEMC permeability can be tuned by adjusting salt concentration, offering potential for controlled transport applications.