| Natural bio-minerals are fabricated through a series of complicated and precise methods by living organisms in nature, they always have some unique components or structures which can bring them remarkable function when compared with artificially synthesized materials. And bio-mineralization always takes place in natural conditions without heating process or other expensive additives, which means bio-mineralization has a wide application prospect.Some studies have been done on proteins or cells to direct the formation of inorganic materials in vitro. However, in most situations, a single protein or a combination of several proteins cannot be substituted for an entire natural organism as a cradle for the growth and formation of biominerals. The complexity and ingenuity of biological system are still beyond chemists' reaches. Herein, we propose to directly take advantages of natural biological systems as platforms for fabricating ceramic materials in vivo with exquisite structures, functions, and/or properties, at ambient temperature.Nacre is a sort of inorganic-organic hierarchical composite which is fabricated by mollusks in nature, the special structure gives it remarkable mechanical properties. In our work, we want to mimic the grow process and environment of nacre. To use cristaria plicata as a platform to fabricate materials, these materials were characterized by XRD? FE-SEM?TEM etc. Analyzed the changes of morphology and structure of fabricated materials, and investigated the mechanism of bio-mineralization.In our work, amorphous SiO2 plates and Fe2O3 plates were put into the internal of cristaria plicata. After months' cultivate, compact and homogeneous SiO2/protein composites and Fe2O3/protein composites. And we also found some special rodlike structures which constructed by Fe2O3 particles coated with CaCO3.Secondly, protein solution was extracted from cristaria plicatas. Amorphous SiO2 plates and Fe2O3 plates were put into protein solutions in vitro, after days' mineralization, we also got compact and homogeneous SiO2/protein composites and Fe2O3/protein composites. However, the rodlike structures were not found.The results showed: the compact and homogeneous inorganic-organic composites were constructed by deposition of protein, the higher the protein's concentration, the deposit speed is faster. And the protein affinity is also related to the deposit speed. However, when in vitro, there was no extra energy for CaCO3's nucleation and growth, so the rodlike structures which constructed by Fe2O3 particles coated with CaCO3 were not found. Also, we tested the crystal properties of SiO2/protein composites synthesized in vivo or vitro and SiO2/organic composites synthesized by mechanical mixing. The results showed that: the crystal temperatures of SiO2/protein composites synthesized in vivo or vitro are 200? above the crystal temperatures of SiO2/organic composites which arise from the special compact and homogeneous structure.We also did some fundamental investigate on protein's influence in the fabrication of Fe2O3 powder. The result showed: the higher the protein's concentration, the bigger the Fe2O3 particles' size, and the Fe2O3 particles' shape is more like sphere.The significance of these results for further research is to extend the present methodology to prepare materials, especially opens countless possibilities to design and produce ceramics under environmentally benign conditions. |
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