Abstract:A novel nano-sized microcapsule was prepared through layer-by-layer (LbL) assembly, using calcium carbonate nanoparticles as sacrificial inorganic template and sodium alginate (SA) and polyethyleneimine (PEI) as wall material. Ciprofloxacin, as antibacterial medicine, was selected as model drug to study the encapsulation and release properties of the microcapsules. The results show that the mean size of calcium carbonate template is reduced to 432 nm after dispersing into sodium dodecyl sulfonate (SDS) solution under sonication. SEM results show that the prepared microcapsules have the diameter under 100 nm, typical creases and collapse are found on the surface of the microcapsules. The nano-sized SA/PEI microcapsules show a high ciprofloxacin loading capacity of 27.96%.