Calcium-containing disk pattern from microspheres of chitosan with alginate

Microstructures bridge the molecular and the macroscopic scales. Disk-patterned microstructures obtained from microcapsules in this work are assembled through layer-by-layer which allowed depositing the natural polysaccharides chitosan (CS) and sodium alginate (SA) on porous CaCO3 microparticles. Besides CS and SA assembled outside CaCO3 microparticles, some CS and SA were also encapsulated by permeation in the pores of CaCO3. During the dissolution of CaCO3, the Ca2+ cations from decomposed CaCO3 were found to interact with alginate (AL) anions and to form Ca2+–AL scaffolds. The adhesion arising from the OH groups in polysaccharides to solid surfaces was attributed to the disk-patterned microstructures. The calcium content (2.290×10−10mg) in each (CS/SA)4 microstructure amounts to about 1% of the total mass of the CaCO3 core. This work thus demonstrates the interaction between the decomposed core elements and the polysaccharides existing both inside and outside the porous cores. Such microstructures containing both Ca2+ and natural polysaccharides have potential applications in biological and medical systems. ► Layer-by-layer-assembled capsules of CaCO3∣polysaccharides are employed. ► Ca2+ from decomposed CaCO3 interacts with alginate anions and forms scaffolds. ► Scaffold and adhesion of polysaccharides lead to disk-like microstructures.