Incubation of CaCO₃ microparticles in chitosan (CS) solution at pH 5.2 and following with ethylenediaminetetraacetic acid disodium salt (EDTA) treatment resulted inCS single component microcapsules with an ultra-thick wall structure. Repeating the incubation causedstepwise increase of wall thickness and finally resulted in CS microcapsules with a layered structure. This unique method is mediated by precipitation of CS on the CaCO₃ particles as a result of pH increase caused by the partial dissolution of CaCO₃. The obtained CS capsules arestable at neutral pH.

Reference：

Fabrication of Chitosan Single-Component Microcapsules With a Micrometer-Thick and Layered Wall Structure by Stepwise Core-Mediated Precipitation.

Yuanyuan Han,Weijun Tong,* Yuying Zhang, Changyou Gao*.Macromolecular Rapid Communication, DOI =10.1002/marc.201100685.