Biomimetic Synthesis Of CaCO3 Using Amino Acid As Organic Matrix

Biological mineral is the step which minerals are becoming in organism, in fact, they are very important components of organism and high-performance composite materials. The most immediately striking aspect of biomaterials is the range of exquisite and unique morphologies, which are frequently disparate from their synthetic counterpart. Typical products of biomineralization are bones, teeth, shells, pearls, and so on. The general principles of biomineralization are introduced into the synthesis process of inorganic materials. Simulating the biomineralization process of the nucleation and growth of inorganic materials mediated by organic matrixes and biomimetic synthesis of inorganic materials with higher performance and more exquisite morphologies have become the focus of material science.CaCO3 is one of the important fillers used in the industries of plastics, rubber, paint, and so on. As an important harvest of nanotechnology, nanoparticles have attracted many attentions in the field of materials science. However, the nano-CaCO3 is easily aggregated because of small particle size, high surface activity and energy. Controlling the particle size during the preparation process, avoiding the aggregation of particles and inducing the powders to re-disperse in the medium are'hot topics'in the field of nanomaterials. Surface modification of CaCO3 would lead to a great expansion in its applications since mineral particles are hardly dispersed in a polymer matrix.According to the general principles of biomineralization, we used amino-acid as the organic template, which can efficiently interact with CaCO3 crystal, to control the polymorphs and the morphologies of CaCO3. These as-prepared CaCO3 materials with unusual morphologies can be potentially promising candidates for advanced materials due to the importance of shape and texture in determining properties of materials. The amino acids in organisms constitute the basic units of protein molecules, the organisms with the most basic life activities related to substances and biological activities of life are closely related. It is an indispensable component of nutrition with a special antibody in the physiological function of the bodyIn this paper, we synthesize calcium carbonate and modified the calcium carbonate surface with new ideas. In accordance with the basic principles of biomineralization, we select amino acids as the template to regulate calcium carbonate growth and crystal morphology. Series calcium carbonate materials with special profiles synthesize in biomimetic ways and this depth study provides a theoretical and experimental basis.Aspartate is used as organic substrate to biomimetic synthesize calcium carbonate. The different weight of aspartate was dissolved in deionized water with stirring. Put it into the aged calcium hydroxide slurry, let them react at room temperature with stirring for 0.5 h, then the liquid was transferred into the cube reactor, carbon dioxide and nitrogen-gas mixture are introduced into the reactor, finally, nano-particles (diameter approximately 40 nm around), the flower-like calcium carbonate crystals, branched calcium carbonate crystals, short-chain (average diameter of about 30 nm), irregular morphology and calcium carbonate crystals with good dispersion have been synthesized. From the X-ray test results we can know the products are all calcite with high purity, also, infrared spectroscopy indicate that ion bond of aspartate reacts with calcium carbonate. All these proved that aspartate can control the crystal size and morphology of calcium carbonate, and we will reach nano-sized calcium carbonate. From the test, we can know that the structure of organic molecule is the key to control the formation if special nuclei in the mineralization step.Methionine was used as organic substrate, biomimetic synthesized calcium carbonate in liquid phase. 20 mg methionine was put into calcium chloride solution, stirred till the solid dissolved in the mixture. Then we dropped the mixture into sodium carbonate solution slowly with stirring. Aged for 30 minutes after dropping, a unique morphology of ginger-like calcium carbonate was becoming. From scanning electron microscope photographs, we can see that the ginger-like calcium carbonate and irregular hexagon calcium carbonate are together in the picture. From the view of overall photos, the ginger-like calcium carbonate comes from the irregular cube; from the view of partial enlarge pictures, we can see that the ginger-like morphology are made of 100-200nm self-assembled particles under the induction effect of methionine. The X-ray powder results show that the products are consisted of calcite and vaterite. In the picture of infrared spectra, CH3 and -CH2 stretching vibration peak which belongs to methionine can be seen clearly. This can prove that methionine do react during the formation of calcium carbonate and TGA results also prove the above ideas. In the system in the presence of methionine, vaterite can exist at the end of test, it means methionine can prevent the transition from vaterite to calcite in the solution.This may be the existence of methionine can reduce the vaterite surface energy and stabilize the vaterie. The procedure may be due to the C=O bond with negative charge in amino acids lean to oxygen atoms, Ca2+ with positive charge was attracted by this, then CO32- combined with the chelate material of amino acid with Ca2+, this would be the critical particles of vaterite.The multi-shaped calcite particles have been biomimetically synthesized through the carbonation route, in which CO2 gas at a constant gas feed rate of 0.1 L/min is bubbled through aqueous slurry of calcium hydroxide, in the presence of alanine acid (ALA) and different temperature was selected. The effects of the reaction temperature and the concentration of ALA on the nucleation and growth of calcite were investigated. The possible growth mechanism of the calcite particles was discussed. This research not only can make us further understood the general principles of biomineralization, but also can open up a new avenue of industrial production of CaCO3 particles with exquisite and unique morphologies due to the preparation method employed by us is simple, low-cost, mild condition.Exquisite and unusual needle-shaped CaCO3 particles were successfully biomimetically synthesized through a facile precipitation reaction of Na2CO3 with CaCl2 in the presence of histidine(HIS). The X-ray powder results showed that the products were consisted of calcite. From SEM picture, we could see that the needle-like morphology was made of 20-40nm self-assembled particles. The imitation of biological mineralization, which reflect the structure between inorganic materials and organic matrix and specific requirements of stereochemistry.In this paper, we attempted a biomimetic method to obtained CaCO3 with special properties, introduced a novel ideal to synthesis CaCO3 under the control of amino acids. For the benefits of simple, uninterrupted and inexpensive products, this innovatory technique has potential use in application and guide meaning in large-scale industrialization manufacture of CaCO3.