Fig. 1.

(A) Encapsulation of S1 subunit in CaCO₃ microspheres, followed by coating with TA/PEG films by LBL assembly. (B-D) SEM images of the empty CaCO₃ microspheres (B), BSA@CaCO₃ microspheres (C) and BSA@CaCO₃/(TA/PEG)₅ microspheres (D). (E, F) Size distribution of empty CaCO₃ (E) and the BSA@CaCO₃ (F) microspheres determined using dynamic light scattering (DLS). (G) Zeta potential of BSA@CaCO₃ microspheres, the same microspheres deposited sequentially with a PEI layer and a 5 bilayer TA/PEG film.