Abstract: In a solution containing water soluble chitosan(CML) derivative which was obtained by grafting lactic acid and methacrylic acid, CaCO₃ microparticles doped with the CML[CaCO₃(CML)] were fabricated. Layer-by-layer assembly of polystyrene sulfonate sodium salt(PSS) and poly(allylamine hydrochloride)(PAH) was then conducted on the CaCO₃(CML) microparticles to form core-shell particles. Core removed by disodium ethylenediaminetetraacetate dihydrate yielded the PSS/PAH multilayer microcapsules having the CML in their interiors. The CML hydrogel was formed in situ by a photoinduced crosslinking. The as-prepared microcapsules preserved the microscopic morphology of their template particles. Unlike the traditional multilayer microcapsules, these CML hydrogel filled microcapsules remained their spherical shape after drying, but their size was decreased from 6.8 μm to 4.6 μm. The capsule size and shape were recovered after hydration. These microcapsules showed a high loading efficiency of fluorescent dyes including negatively charged fluorescein and bovine serum albumin, positively charged rhodamine, and neutral Nile red in both water and organic solutions.

Key words: Layer-by-layer assembly, Microcapsule, Gel, Loading