Development of crystallization nanotechnology by mimicking marine organisms

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Calcified shell is composed of two polymorphs of calcium carbonate, aragonite, and an organic matrix. We investigated the role of lectins as the organic matrix to explore the biomineralization, which is relevant to a range of industrial processes. The processes includes the direct biotechnological exploitation of biogenic materials, the design of novel composite materials by in situ precipitation, and the mimicking of biological processes in an inorganic context. The C-type lectins in the hemolymph of the acorn barnacle, Megabalanus rosa, was shown to participate in mineralization as well as defense. The lectins inhibited calcium carbonate crystallization, whereas the immobilized ones promoted it. The sugar chains of the lectin was demonstrated to play an important roles in the stability and activity concerning the control of mineralization. Observations by scanning electron microscopy revealed modifications in the size and morphology of the crystals grown in the presence of various lectins, depending on the numbers and localization of acidic amino acid residues and their amide forms.Microstructure and orientation distribution of aragonite crystals in the nacreous layer of cultured Pteria penguin were investigated. Helical patterns drawn by growth forefronts of the nacreous layer were observed by a laser microscope for the good-quality shell, whereas no clear pattern was observed on the nacreous layer surfaces of the bad-quality shell. The difference in the orientation distributions of the crystals provided different qualities of pearls built in the shells.