Urease-loaded colloidosome microcapsules with SiO 2 nanoparticle shells and gellan gel cores were prepared facilely and highly efficiently by self-assembly of colloidal particles at the liquid-liquid interfaces and subsequently in-situ gelation of gellan gum. The urease-loaded colloidosome microcapsules were used as an enzymatic reactor to produce calcium carbonate precipitates by urease-catalyzed urea hydrolysis in the presence of calcium cations. The CaCO 3 /SiO 2 shells were formed finally around the gellan gel cores. The colloidosome microcapsules used as a biomimetic reactor has been demonstrated for the first time.
