Synthesis of Calcite with Novel Morphologies and Epitaxial Growth Calcium Bilirubinate (CaBR) on Calcite and Effects of Dipalmitoylposphatidylcholine (DPPC) Monolayer and Dextran

Controlled growth of calcium carbonate crystals with complex forms was achieved using dextran as a crystal growth modifier beneath a dipalmitoylphosphatidylcholine (DPPC) monolayer, and calcite-core-calcium bilirubinate (CaBR)-side multiple crystals were also observed owing to the epitaxial growth of CaBR crystals on calcite. During the process, interactions between the DPPC monolayer and calcium ions were studied based on the analysis of the surface pressure−molecular area isotherms. Control over the crystallization of calcite with novel morphologies, such as octahedral crystals and round calcite disks, has been observed. Remarkable morphological changes and continuous structural evolution of calcite from rhombohedral crystal to octahedral crystal to uniform round disks and polyhedrons as concentrations of dextran increased have been observed. Moreover, semirigid multiplex templates consisting of calcium carbonate crystals and DPPC monolayers were established under physiological pH conditions, and epitaxial growth of sheet calcium bilirubinate crystals on calcite had been observed to form calcite-core-CaBR-side multiple crystals. The dynamic process of formation of multiple crystals was analyzed by monitoring the morphologies and components of crystals in different crystal stages. The possible formation mechanism of polymorphous calcite and calcite-core-CaBR-side crystal has been proposed, which provides an important insight into the epitaxial relationships between the surfaces of inorganic and bioorganic complex crystals and affords a detailed nanoscale understanding of how inorganic seeds may have a significant effect on crystal nucleation and growth processes.