Scheme 1.

Schematic illustration for the preparation of MAPs and MACPs. MAPs were fabricated by coating cross-linked alginate on MNPs using Ca²⁺ as the cross-linker. MACPs were prepared by alternatively depositing CHI and sodium alginate (SA) on MAPs based on the electrostatic interaction between the two biopolymers. The alternative coating was repeated until MACPs with desired number of layers were obtained (Stage 2 and 3). MACPs 1, 2, 3, 4 and n represent CMACPs that possess 1, 2, 3, 4 and n layers of polymers coated on MNPs respectively.