Carbonate crystal growth controlled by interfacial interactions of artificial cell membranes

Morphology of carbonate crystals grown on the surface of artificial cell membranes was controlled by changing the interfacial chemistry. For octadecyltriethoxysilane (OTE) films with terminal methyl groups interacting little with an aqueous calcium carbonate solution, calcite (104) crystals were formed. Polymerized pentacosadiynoic acid (PDA) films with terminal carboxylic acid groups induced deposition of calcite (012) crystals aligned along with each other within a polymer domain. On the other hand, stearyl alcohol (StOH) films with terminal hydroxyl groups induced deposition of aragonite crystals. When PDA was mixed with StOH, the 8∶1 PDA∶StOH (molar ratio) film produced dominating calcite (012) crystals without any crystal alignment, and the 4∶1 mixture film produced minor calcite (012) crystals and major aragonite crystals. For the 2∶1, 1∶1, 1∶2, and 1∶4 mixture films, aragonite crystals were dominating. Hence, it is found that the chemical composition at the interface plays a very important role in controlling the morphology of deposited carbonate crystals.