凝胶体系中生物矿物生长的研究进展

近年来,生物矿化的模拟和仿生材料的研究十分引人注目.凝胶体系是模拟生物矿化的有效介质.本文综述了凝胶中羟基磷灰石、透钙磷石、磷酸钙等磷酸盐,文石、方解石、球霰石等碳酸钙,碳酸钡和草酸钙等生物矿物生长的研究进展,讨论了生长参数如凝胶种类、凝胶化学性质、吸附到凝胶表面的物质种类、介质pH、生长时间等对这些矿物晶体生长的影响,最后指出了该领域所面临的问题和将来的发展方向.     

单分子膜诱导下晶体生长中的晶格匹配

有机基质与无机晶体的晶格几何匹配是导致生物体内矿物有序生长并具有特殊理化性质的重要因素之一.作为模拟生物矿化的重要模板之一,Langmuir单分子膜具有独特的优势.本文综述了单分子膜诱导下CuSO4、Na2SO4、PbS、CdS、BaF2和CaF2等晶体生长过程中的晶格匹配,讨论了单分子膜亲水头基、膜的电荷性质、膜聚集态等因素对膜控晶体生长过程中晶格匹配的影响.指出了该领域所面临的问题和将来的发展方向.     

Deinococcus Radiodurans表面氨基修饰对钙锶生物矿化自组装的影响

研究中通过表面基团屏蔽探索耐辐射奇球菌表面氨基对钙锶生物矿化及其自组装过程的影响.结果表明:(1)在Deinococcus Radiodurans作用下,体系倾向于形成文石晶型;(2)屏蔽氨基后,氨基对方解石晶体的抑制作用消失,[Ca2+]高时诱导晶体从文石转变为方解石,[Sr2+]高时诱导晶体产生空壳结构;(3)在D.Radiodurans作用下,文石晶体的生长属于经典的棒-哑铃-球自组装模型;屏蔽氨基后,文石晶体的生长为球壳和哑铃空壳的空壳自组装过程.综上所述,耐辐射奇球菌表面氨基能促进晶型的转换,控制晶体的自组装.本研究结果可为阐释微生物诱导生物矿化自组装过程提供参考.     

生物矿化法制备平片状YBCO粉末的超导连接性及补氧退火对超导连结性影响的研究

本文报道了用生物矿化法制备平片状YBCO粉末的过程,并通过对Bean模型参数选择研究了YBCO粉末内部晶粒间的超导连接性.结果表明在这种平片状YBCO粉末内部存在有自发的晶粒间超导连接,这种超导连接存在于由平片状YBCO晶粒构成的具有相似生长方向的晶粒簇当中,而在77 K下,超导连接区域平均包含3～5个平片状晶粒.本文还就补氧退火中烧结温度和保温时间对平片状YBCO粉末超导连接性的影响进行了系统的研究.     

蒙脱石基生物纳米复合功能材料及应用研究

生物纳米复合功能材料的理论与应用研究已成为关注焦点,是生命科学与材料科学前沿交叉方向.粘土矿物是一类天然纳米结构的硅酸盐矿物,其特殊的层状纳米结构,使其具有吸附能力强,稳定性好,应用广泛等特点.本文主要介绍了蒙脱石基生物纳米复合功能材料在酶催化、抗菌、医药和环保等领域中的研究、开发及应用情况,并探讨了粘土矿物基纳米复合材料的发展前景.     

两株嗜冷碳酸钙矿化菌对大理石表面修复效果研究

细菌诱导的矿化沉积是一种有效修复和保护石质文物的方法.为探究生物矿化法应用于寒冷地区石质文物表面的修复效果,本文在黄龙高寒钙华沉积区分离到2株具高产碳酸酐酶(CA)活性的嗜冷型细菌菌株,并在大理石试件表面进行诱导矿化沉积.采用pH计、SEM、XRD等仪器,通过对矿化沉积过程中pH值、试件表面矿化沉积变化量、试件表面矿化沉积物的晶型晶貌、试件表面吸水性与透气性、耐酸度等的测定来表征嗜冷型碳酸酐酶产生菌在大理石试件表面矿化沉积的修复效果.结果表明,无论是存活菌还是灭活菌都在大理石试件表面生成了致密的碳酸钙矿化层,均为方解石晶型,形貌受菌体调控,活菌生成的矿化层更为均一和致密,长期作用比短期作用效果更明显,具有矿化层的试件在吸水性、透气性和耐酸度上都体现出更具防腐蚀的能力.其结果可为石质文物的修复提供一定的理论依据.     

Cr2O3和煅烧温度对铝钛渣制备钛酸铝材料性能影响（英文）

为了提高合成钛酸铝烧结性和钛酸铝的合成率,以铁合金厂铝钛渣和二氧化钛为主要原料,以Cr2O3为矿化剂,在不同煅烧温度下(1400℃、1450℃和1500℃)条件下,通过固相烧结方法合成钛酸铝材料。用XRD和SEM对煅烧后试样的矿物相组成和显微结构进行分析,用X’Pert plus软件计算合成材料中钛酸铝的晶格常数和晶胞体积。重点讨论了矿化剂Cr2O3加入量和煅烧温度对合成钛酸铝材料矿物相组成、晶格常数、显微结构及烧结性能的影响。结果表明,由于矿化剂中Cr3+对钛酸铝结构中Al3+和Ti4+的置换作用,钛酸铝晶体结构发生畸变。随着矿化剂Cr2O3加入量增大,钛酸铝晶胞常数和晶胞体积逐渐增大,置换作用所造成的结构缺陷加速了固相反应烧结,钛酸铝材料合成率逐渐增大。同时,随着煅烧温度的升高,结构中所产生的热缺陷也会促进合成钛酸铝的固相反应和烧结性,钛酸铝材料合成率增大,微观结构中裂纹数量逐渐减少。     

玻璃基片表面纳米结构氧化锆聚集体组装的SEM研究及其机理初探

以纳米粒子为基组装的有序结构体系,既具有纳米小颗粒本身的性质,同时通过纳米粒子之间、纳米粒子与基体界面的耦合,有望产生新的效应.本文利用含有双亲分子的反胶团微乳体系,人为处理基底提供活性点模拟生物矿化过程,构筑聚集体-基质复合材料,完成玻璃基片表面不同形貌氧化锆的组装,并对机理进行了初步的探讨.     

硫酸软骨素/L-谷氨酸对碳酸钙形貌及晶体生长影响的研究

根据生物矿化原理,通过CO2的缓慢扩散,在硫酸软骨素(CSB)/L-谷氨酸二元体系中,与富集在有机/无机界面钙离子的结合,合成了不同形貌的碳酸钙.系统地研究了室温下各种因素对碳酸钙晶体形貌和晶型的影响.产物用XRD、SEM和FT-IR进行表征,FT-IR和XRD分析表明:所得的晶体为方解石的晶型,SEM表明体系中CSB的浓度,pH值,CSB/L-谷氨酸的浓度比对碳酸钙形貌起着重要作用.通过改变实验条件得到了椭球型,哑铃型等形貌碳酸钙晶体,并对其可能的形成机理进行了分析.     

在卵磷脂溶液中仿生合成无定形碳酸钙

在含有卵磷脂的水溶液中仿生合成了无定形碳酸钙.所得样品用扫描电镜(SEM)、傅立叶红外光谱(FT-IR)、X射线衍射(XRD)和热重分析(TG)等分析方法进行了表征.研究表明:具有一定浓度的卵磷脂可以利用其端基磷酸根基团稳定无定形碳酸钙,这为理解在生物体内的环境中生物矿物的形成机理提供了一种新的途径.     

Controlled deposition and transformation of amorphous calcium carbonate thin films

Controlled synthesis of amorphous calcium carbonate (ACC) films was realized by using the multiple templates, which are composed of a self‐assembled film (SAF, insoluble Poly (ε‐caprolactone) film) and a soluble modifier (poly allylamine), as modifiers. The formation of self‐assembled film was analyzed by monitoring the morphologies using atomic force microscopy. Even more noteworthy, using anhydrous ethanol as media, the ACC‐to‐vaterite‐to‐calcite transformation was also investigated, and the obtained products were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and X‐ray diffraction. The results demonstrated that organic solvent has profound influence on transformation of amorphous calcium carbonate thin films. In the air of anhydrous ethanol, the controlled synthesis of calcium carbonate films with different morphologies, such as planar films with a few sporadic particles, symmetric rhombohedral crystals, novel crystals with symmetrical terraced convexity formation of calcite, was obtained by the fine‐tuning of induction time. It provides a new and simple method to prepare polymorphic CaCO₃ crystal films from the ACC films by controlling the crystallization process (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

柠檬酸废渣制备硫酸钙晶须的研究

硫酸钙晶须是具有良好的力学性能和广泛应用前景的增强材料,利用柠檬酸废渣制备硫酸钙晶须,不仅可以生产出具有较高利用价值的材料,而且大大降低了成本并处理了废渣,起到"变废为宝"的作用.本文针对硫酸钙难溶的特性,采用了水热合成法成功制备了硫酸钙晶须,并讨论了多种因素对其影响,初步探讨了其生长机理,为其工业化生产提供理论基础.     

Effect of sodium oleate on the agglomeration of calcium carbonate

The effect of Na‐Oleate on the agglomeration of calcium carbonate was investigated. Oleate is determined by Infrared spectroscopy. In order to detect the amount of Oleate adsorbed on the calcium carbonate crystals, the differential thermal analysis method was used. The agglomerate size and zeta potential were investigated as a function of Na‐Oleate concentration and pH value. It was found that the amount of Na‐Oleate adsorbed on the calcium carbonate is not only depending on the concentration but also on the pH value and zeta potential. The results also show that the critical Na‐Oleate concentration, where the maximum Na‐Oleate adsorption was reached, was found approximately 300 ppm under the selected experimental condition. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Calcium oxalate crystallization in the presence of amino acids,proteins and carboxylic acids

Reactive crystallization of calcium oxalate was investigated in the presence of amino acids, proteins and carboxylic acids at different pH and temperatures. Average particle size, filtration rates of calcium oxalate crystals obtained in the absence and presence of additives were determined. The influence of pH, temperatures and additives on crystal morphology of calcium oxalate were also investigated and discussed by SEM analysis. TG‐DTA, FT/IR and XRD analysis were carried out for all investigated conditions. Average particle size of calcium oxalate was affected significantly by the additive type and concentration. Variation of crystal morphology depending on type and concentration of the additives affected the filtration characteristics. Majority of calcium oxalate crystals occurred in the form of calcium oxalate monohydrate except those in the presence of tartaric acid. TG‐DTA, FT/IR and XRD analysis proved that calcium oxalate monohydrate and calcium oxalate dihydrate mixtures are formed in the presence of tartaric acid. The effect of all additives on scale formation was also investigated. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

The role of silica and alkaline earth metals with biomolecules in the biomineralization processes: the eggshell's formation and the crystallization in vivo for x-ray crystallography

This contribution is a scientific journey divided into three parts. In the first part, we review the role that silica biomorphs of alkaline earth metals have played in the formation of complex structures as a reminiscence of the chemistry of the primitive life on Earth. These biomorphs, and their variety of forms synthesized by simple chemical reactions, can nowadays be experimentally used to explain some mechanisms of biomineralization in living organisms. In the second part, we review the role of calcium carbonates in the formation of eggshells in avian. The mechanism of the mineral eggshell´s formation of the biogenic calcite deposited on an organic matrix is revised. The competitive crystal growth mechanism of the mineralized part orientates these crystals preserving the semispherical shape of the egg. We are using these eggshell formations as a second model to understand the biomineralization processes in Nature. The third and final part is about the importance that biomineralization concepts have to produce hybrid materials for the future. This has allowed us to obtain tailored size control of complex morphologies by synthetic chemical procedures that give rise to these new materials’ specific forms and ad hoc properties. We conclude this part with the advantage of knowing the biological mechanisms, based on molecular biology concepts, to obtain protein crystals in vivo and in cellulo techniques. Both methods use the cellular machinery of growing biocrystals in specialized cells that have evolved through millions of years. This new way of producing protein crystals has been trending topic for modern crystallography when using the facilities of the X-ray free-electron lasers (four generation of synchrotrons) for megahertz serial crystallography.     

不同结构物质和有机基质对草酸钙晶体生长的促进作用

本文综述了有机大分子、小分子和有机基质对尿石矿物草酸钙(CaOxa)晶体成核、生长和聚集的促进作用.从促进物的分子结构和草酸钙晶体的晶面性质等方面讨论了不同类型促进物的作用机理.最后指出了该领域所面临的问题和将来的发展方向.     

Compositional analysis of a polymer-induced liquid-precursor (PILP) amorphous CaCO3 phase

Amorphous calcium carbonate (ACC) has been of keen interest in the biomimetics field because of recent evidence which suggests it plays an important role in biomineralization. In this report, an in vitro model system is used to examine the composition of an amorphous phase generated by polyanionic process-directing agents, such as the sodium salt of polyaspartic acid (Pasp), which is considered a simple mimic to the proteins associated with calcific biominerals. This additive leads to the formation of a highly hydrated, amorphous mineral precursor to calcium carbonate (CaCO₃), referred to as a polymer-induced liquid-precursor (PILP) phase. The precursor phase was collected by centrifugation, and the quantity of precursor phase and the water content were determined. It was found that Pasp promotes and stabilizes the amorphous precursor, which has a composition that steadily changes with time as the polymer and water are excluded. Elemental analysis was used to investigate the role of the polymer in influencing the calcium/carbonate ratio, the water content, and the amount of precursor phase. Raman and ATR-FTIR spectroscopy were used to compare the compositions of the precursor phases generated with different polymeric concentrations. The role of Pasp in generating and stabilizing the ACC precursor phase is discussed.     

Preparation and characterization of bioceramics produced from calcium phosphate cements

The present work reports a method for preparing calcium phosphate ceramics by calcination of calcium phosphate cements composed mainly of calcium deficient hydroxyapatite (CDHA). It was found that hardened cements calcinied at temperatures from to 600 to 1300 °C were transformed to tricalcium phosphates. Moreover the compressive strength was determined and porosity was estimated as a function of the calcination temperature. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

The influence of crystallization conditions on the onset of dendritic growth of calcium carbonate

Understanding the crystallization of calcium carbonate is relevant in numerous fields like biomineralization, geology and industrial applications where calcium carbonate forms. In order to enhance the knowledge about the formation of calcium carbonate with focus on the vaterite polymorph, in this work calcium carbonate has been crystallized in aqueous solutions at temperatures from 5 °C to 90 °C. Special attention has been directed to higher temperatures for which the effect of the initial supersaturation on the resulting crystal morphologies and the onset of dendritic growth have been studied. In analogy to snow crystal formation, it has been found that in a certain temperature range hexagonal plate‐like crystals form at low supersaturation whereas dendritic patterns start to appear at higher supersaturation. The symmetrical branches characteristic for dendritic growth get less pronounced as the temperature is decreased. The results reported here related to the interdependence between supersaturation, crystal morphology and growth mechanisms, can be used in future works to predict particle formation and to design crystal architectures. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)