Permeability of S-layer coated polyelectrolyte capsules

Hollow polyelectrolyte capsules have recently attracted a wide interest as a new class of drug delivery vehicles. They can be fabricated by means of the Layer by Layer technique which is simple, and versatile and allows the obtainment of programmable shell composition, diameters, thickness, and permeability. Hollow capsules, ranging in size from tens of nanometers to tens of microns, can be developed on the surface of spherical templates subsequently removed under acidic conditions. Their inner volume can be loaded with a wide variety of therapeutic agents and their surface functionalised with biomolecules to optimize drug targeting. To this regard, crystalline bacterial cell surface layer (S-layer) represent a promising solution to introduce an array of ordered functional groups on the surface of the capsule shell to which biomolecules can be covalently bound. In this work polyelectrolyte capsules with the architecture (PAH/PSS)4 Slayer were developed and their permeability to dextran conjugated to the fluorescent dye FITC investigated. Results show a successful stepwise assembly process and encapsulation of the tested fluorescent complex inside of the polyelectrolyte capsules putting in evidence the high potential of the developed system for the encapsulation and targeted release of therapeutic agents.