Fig. 1.

Fabrication of mesoporous PSI microspheres. A. The fabrication protocol for uniform, dispersed microspheres showing the change in appearance before the CaCO₃ template is removed by chelation. B. The DIC image of fabricated template microspheres with no PSI, showing their monodispersion and uniform size. C. The scanning electron microscopy (SEM) image of a cluster of PSI-containing microspheres at a ratio of 500:1 BSA:PSI at the pre–cross-linking stage shows the smooth CaCO₃ template surface. A rare hollow microsphere is pointed out with a white arrow. D. Focused ion beam dissection of the same pre-chelation sample in 1C reveals that the microspheres are solid and uniform throughout.