Effect of agar hydrogel and magnesium ions on the biomimetic mineralization of calcium carbonate

Here, agar hydrogel was selected as diffusion medium and template to control the biomimetic mineralization of calcium carbonate (CaCO₃). Due to three dimensional network structures and abundant functional groups (such as, hydroxyl groups), Ca²⁺ ions were uniformly distributed in the network and electrostatically attracted. The diffusion speed and range of CO₃^2? ions were mediated by the concentration of hydrogel medium. Under the synergistic effect of Mg²⁺ ions, the crystal CaCO₃ was induced by gas phase diffusion method in the hydrogel system. The results showed that the concentrations of Mg²⁺ ions and agar hydrogel had no obvious effect on the calcite phase of CaCO₃, but the morphologies and sizes changed with concentrations of medium and Mg²⁺ ions. Attribute to template effect, the crystallization behavior and growth rate of CaCO₃ crystals were regulated. Since Mg²⁺ ions were easily adsorbed on the surfaces of unit cell, the unique structure of CaCO₃ was precisely controlled. This study provides a useful reference and inspiration for the understandings of the contributions of ion supply rate in bio-mineralization and hydrogel medium in biomimetic mineralization.     

脂肪酶仿生固定化及性质

将仿生钛化过程用于脂肪酶固定化,研究了该过程中工艺条件对脂肪酶固定化的影响及固定化脂肪酶的性质.结果表明：0.5 mL浓度8 mg/mL精蛋白诱导剂、0.5 mL浓度6 mg/mL脂肪酶与1 mL,0.25 mol/L钛前驱体（Ti-BALDH）在pH 7.5,0.05 mol/L磷酸盐缓冲液为反应介质的条件下,脂肪酶...     

Effects of calcium carbonate polymorph on the structure and properties of soy protein-based nanocomposites

Novel protein-based nanocomposites were well prepared by in vivo synthesis and co-precipitation of soy protein isolate (SPI) with calcium carbonate (CaCO3) in an aqueous solution. The resultant CaCO3 in the nanocomposites was identified as calcite- and aragonite-type, respectively. The morphology and structure of the CaCO3/SPI composites were investigated by means of wide-angle X-ray diffraction, Fourier transform infrared spectra, scanning electron microscopy, and high-resolution transmission electron microscopy. The results revealed that the polymorph and the size of CaCO3 in the nanocomposites were dependent on its content, pH, and the conformation of soy protein. At the content of more than 5%, CaCO3 was changed into calcite crystal with the preference of growing along (104) plane. However, at lower content of less than 5%, CaCO3 preferred to form aragonite in the composite as a result of the modulation by soy protein. The aragonite nanocrystals were arrayed in the direction of (111) plane and self-assembled along beta-sheet planes of soy protein polypeptides. The mechanical properties, thermal stability, and water resistance of the CaCO3/SPI nanocomposites were significantly improved as a result of the nanosized effects. Interestingly, the aragonite/SPI nanocomposite exhibited higher tensile strength (about 50 MPa) than that of calcite/SPI, owing to a good compatibility and strong interaction between aragonite and soy protein polypeptides. This work provided a simple pathway to develop the soy protein-based bio-hybrid materials with high mechanical strength and valuable information on their structure-properties relationship.     

Methionine sulfoxide and phosphonate containing double hydrophilic block copolypeptides and their mineralization of calcium carbonate

In effort to address challenges in the efficient synthesis of highly functional block copolypeptides, we report use of a combination of functional monomer polymerization and postpolymerization modification to obtain new double hydrophilic block copolypeptides with desirable properties. We prepared copolymers that contain discrete hydrophilic, nonionic poly(l‐ methionine sulfoxide) and Ca²⁺ ion binding poly(l ‐phosphonohomoalanine) segments. The facile and selective postpolymerization conversion of inexpensive, readily prepared poly(l ‐methionine) segments into nonionic, hydrophilic poly(l ‐methionine sulfoxide) segments reduces the need for use of combinations of protecting groups. The complex copolypeptides prepared using this strategy were able to promote formation of CaCO₃ microspheres with tunable polymorphism. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 3707–3712     

碳酸钙微米球的制备与表征

采用醋酸钙和碳酸钠为原料,在反应温度为5℃和柠檬酸三钠质量百分浓度为15%的条件下,采用沉淀法合成出了粒度为1～4μm、分散性好的球形碳酸钙粉体。用扫描电子显微镜(SEM)、X射线衍射仪(XRD)、红外光谱仪(IR)、原子力扫描探针显微镜(ASPM)、光学显微镜、粒度分析仪等对样品进行了表征,并用光学显微镜跟踪考察了碳酸钙微米球的形成过程。结果表明,碳酸钙微米球是由大量纳米级颗粒组装而成。     

纳米碳酸钙的表面改性研究

纳米产品(材料)是当今世界高科技产品之一.纳米碳酸钙作为粉体产品中的一种,以高纯、超细、改性和功能性为标志,广泛应用于橡胶、塑料、造纸、油墨、涂料、医药、化妆品等各行各业[1-2].主要用作填充材料,因粒度超细、分散性好,可以增加填充量,降低制品成本,改善制品性能,提高制品档次,拓宽制品使用范围.近年来,随着CaCO3的超细化、结构复杂化及表面改性技术的发展,极大地提高了它的应用价值.对不同形态的超细CaCO3制备技术的研究,已成为许多先进国家竞相开发的热点[3-5].     

Control of calcium carbonate particle size and shape by precipitation from CTAB/alcohol/hexadecane mixtures

 When used as a precipitation media, emulsified mixtures of cetyltrimethylammonium bromide/n-butanol (E), hexadecane (O) and water (W), controls the size and shape of calcium carbonate particles. Monodisperse 2-micron spherical-calcite particles were obtained in a water-rich region of the mixture, while 2-micron rhombohedral-calcite particles with an aspect ratio near one were obtained in the middle region of the mixture. Replacing n-butanol with i-butanol led to consistent formation of monodisperse spherical particles, while using n-propanol in place of n-butanol limited the number of spherical particles produced in the water-rich region. Received: 17 March 1997 Accepted: 2 May 1997     

铁饼状碳酸钙的制备及性能研究

本文以氯化钙和氨水的混合溶液为水相,聚氧乙烯辛基苯酚醚-10(OP-10)为表面活性剂,正辛醇为助表面活性剂,环己烷为油相配制了反相微乳液.并通过向其中通入CO2气体制备微/纳米碳酸钙,得到了铁饼状的微米碳酸钙.采用扫描电子显微镜(SEM),X射线粉末衍射(XRD)和傅里叶变换红外光谱(FTIR)表征了微米碳酸钙的形貌...     

CaCO3超细粉末的低温水热合成与表征

超细碳酸钙有颗粒尺寸小、比表面积大和表面活性高等优良特性,在橡胶、塑料、纸张、涂料、日用化学品等领域有广泛的应用。因此,研究CaCO3超细粉末的制备方法,开发CaCO3超细微粉的用途,具有十分重要的意义。目前其制备方法主要是碳化法,本文利用水热法制备单一相超细CaCO3粉末,通过不同的反应前驱物在120℃和150℃下进行水热反应直接合成出超细CaCO3粉末,并对产品的结构和形貌进行了表征。     

碳酸钙固定化猪胰脂肪酶的制备及活性研究

本文利用市售普通碳酸钙(general calcium carbonate,GCC)作为猪胰脂肪酶(PPL)固定化的载体材料,研究了不同固定化条件对所制备的固定化酶活性的影响.结果显示PPL固定化于GCC上的最佳制备工艺为:将20 mL酶液与1.50 g GCC放入置于摇床内的三角瓶中,摇床温度设为40℃,摇床转速设为...     

Crystallization of inorganic compounds in polymer solutions. Part I: Control of shape and form of calcium carbonate

Calcium carbonate was precipitated by mixing aqueous solutions of sodium carbonate and calcium nitrate in the presence of water-soluble polymers. When the former was poured into the latter, in which a certain amount of sodium poly(styrenesulfonate) was dissolved, monodisperse spherical crystals were created. The crystal form was vaterite, although, in the absence of the polymer, calcite crystals were obtained in rhombic shape. The factors deciding the shape and form of the crystal were investigated and the role of polymer in the formation of unique crystals was discussed.     

Characterization,by inverse gas chromatography,of the surface properties of calcium carbonate before and after treatment with stearic acid

Summary The interaction of n-alkanes with stearyl chains chemically fixed on the surface of calcite particles is investigated using inverse gas chromatography. Free enthalpy, enthalpy, entropy of adsorption and dispersive component of the surface free energy are determined. Untreated and stearic acid treated calcites have comparable affinities for the alkanes. However, the differences in adsorption entropies point to different interaction mechanisms: gas-solid adsorption for the untreated calcite and gasliquid interactions for the modified sample. Furthermore, for long chains probes, having more than 8 carbon atoms, the loss in entropy is smaller than for shorter chains. Possibly, long chains are only partially inserted in between the stearyl grafts, thus keeping a higher degree of freedom.     

无添加剂条件下文石型碳酸钙晶须制备及影响因素研究

在不加任何结晶控制剂或模板条件下,以CaCl2和Na2CO3为原料,利用复分解反应法制备了具有较好形貌和高长径比,且分布均一的文石型碳酸钙晶须,并利用扫描电镜(SEM)、X-射线粉末衍射(PXRD)和傅里叶转换红外光谱图(FT-IR)等手段对其进行了表征。研究了浓度、滴加速度、反应温度、搅拌速度以及滴加方式等因素对碳酸钙晶须的影响。结果表明最佳制备工艺为:CaC12溶液与Na2CO3溶液的浓度为0.05 mol.L-1,溶液滴加速度为1 mL.min-1,反应体系温度为80℃,搅拌速度为250 r.min-1。     

聚电解质膜PDAC/PSS诱导CaCO3结晶的研究

以模拟软体动物珍珠层的周期性基质控制形成过程制备仿生层状复合材料．将聚苯乙烯磺酸钠(PSS)与聚二烯二甲基氯化铵(PDAC)用逐层浸渍的方法使其组装成多层膜,用于诱导过饱和溶液中CaCO3的结晶,详细研究了膜紫外吸收随组装层数增加的线性变化．扫描电镜和X射线衍射表征了晶体的形貌和结构,(PDAC/PSS)15PDAC膜诱导获得的CaCO3晶体为六面体结构,晶体尺寸为30～40μm;(PDAC/PSS)15膜诱导CaCO3结晶,可以在膜表面获得形貌与珍珠层非常相似的CaCO3晶体,结晶10h获得的晶片结构呈规则的六边形,片尺寸约为10～20μm,X射线衍射结果表明两种晶体的晶格结构与天然珍珠层差异明显,说明静电作用为晶体形貌的主控因素之一,但不是晶格结构的决定因素．复合材料断面电镜照片表明其为层状结构。     

Formation of CaO from thermal decomposition of calcium carbonate in the presence of carboxylic acids

Effect of 5% tartaric, succinic and citric acids on the decomposition of CaCO₃ have been studied by TG-DSC and X-ray diffraction techniques. The decomposition temperature of CaCO₃ is not decreased and at the same time particle size distribution and morphology of CaO are changed as determined by laser granulometer and SEM studies.     

高分子基质作用下多孔碳酸钙的仿生合成

依据生物矿化的基本原理,通过仿生合成的方法,以聚丙烯酰胺作为基质合成了一种有机、无机复合的多孔碳酸钙材料.用X射线粉末衍射(XRD)分析、扫描电子显微镜(SEM)、傅里叶变换红外吸收光谱(FT-IR)和电导率测定等手段对所得复合碳酸钙进行了表征,结果发现该多孔CaCO3晶体为方解石型,并且在结晶过程中,聚丙烯酰胺与CaCO3之间存在着相互作用,本文讨论了这种作用的可能机理.     

聚电解质膜PDAC/PSS诱导CaCO3结晶的研究

以模拟软体动物珍珠层的周期性基质控制形成过程制备仿生层状复合材料. 将聚苯乙烯磺酸钠(PSS)与聚二烯二甲基氯化铵(PDAC)用逐层浸渍的方法使其组装成多层膜, 用于诱导过饱和溶液中CaCO₃的结晶, 详细研究了膜紫外吸收随组装层数增加的线性变化. 扫描电镜和X射线衍射表征了晶体的形貌和结构. (PDAC/PSS)₁₅PDAC膜诱导获得的CaCO₃晶体为六面体结构, 晶体尺寸为30～40 μm; (PDAC/PSS)₁₅膜诱导CaCO₃结晶, 可以在膜表面获得形貌与珍珠层非常相似的CaCO₃晶体, 结晶10 h获得的晶片结构呈规则的六边形, 片尺寸约为10～20 μm. X射线衍射结果表明两种晶体的晶格结构与天然珍珠层差异明显, 说明静电作用为晶体形貌的主控因素之一, 但不是晶格结构的决定因素. 复合材料断面电镜照片表明其为层状结构.