Preparation of polyelectrolyte giant capsules using cross-linked alginate gels as core material

Polyelectrolyte giant capsules whose diameter is in a millimeter level were prepared by a layer-by-layer deposition of poly(allylamine hydrochloride) (PAH) and poly(styrene sulfonate) (PSS) on an alginate (AGA)-Ca ²⁺ sphere followed by dissolution of the AGA core in an ethylenediaminetetraacetic acid or NaCl solution. A fluorescent-labeled bovine serum albumin (BSA) was successfully encapsulated in the PAH/PSS polyelectrolyte capsule. The release of the BSA from the capsule was suppressed in the presence of higher concentration of salt, while the effect of pH was small. In addition, the thickness of the PAH/PSS layer in the capsule wall gave an effect on the release rate of the BSA.