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排序方式: 共有233条查询结果,搜索用时 31 毫秒
61.
Martin Brodrecht Bharti Kumari Dr. A. S. Sofia Lilly Thankamony Dr. Hergen Breitzke Dr. Torsten Gutmann Prof. Dr. Gerd Buntkowsky 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(20):5214-5221
The structure and surface functionalization of biologically relevant silica-based hybrid materials was investigated by 2D solid-state NMR techniques combined with dynamic nuclear polarization (DNP). This approach was applied to a model system of mesoporous silica, which was modified through in-pore grafting of small peptides by solid-phase peptide synthesis (SPPS). To prove the covalent binding of the peptides on the surface, DNP-enhanced solid-state NMR was used for the detection of 15N NMR signals in natural abundance. DNP-enhanced heterocorrelation experiments with frequency switched Lee–Goldburg homonuclear proton decoupling (1H–13C and 1H–15N CP MAS FSLG HETCOR) were performed to verify the primary structure and configuration of the synthesized peptides. 1H FSLG spectra and 1H-29Si FSLG HETCOR correlation spectra were recorded to investigate the orientation of the amino acid residues with respect to the silica surface. The combination of these NMR techniques provides detailed insights into the structure of amino acid functionalized hybrid compounds and allows for the understanding for each synthesis step during the in-pore SPPS. 相似文献
62.
一种新型贝壳基质蛋白的重组表达与功能分析 总被引:1,自引:0,他引:1
贝壳是在贝壳基质蛋白的调控下形成的生物矿化产物,也是生物工程和生物材料学研究的重要对象。贝壳基质蛋白通过调控碳酸钙晶体的成核和生长过程,使贝壳形成有规则的纳米结构并赋予贝壳极强的力学性能。在厚壳贻贝肌棱柱层中鉴定到一种新型贝壳基质蛋白,因其富含谷氨酰胺而被命名为富含谷氨酰胺的贝壳蛋白(Glutamine-rich shell protein,GRSP),该蛋白序列中含18.2%的谷氨酰胺以及PDZ (Postsynaptic density/Discs large/Zonula occludens)和ZM (ZASP-like Motif)结构域。为了解GRSP在生物矿化过程中的分子机理,在序列分析的基础上,采用密码子优化结合原核重组表达策略,获得重组厚壳贻贝GRSP;进一步利用扫描电镜和傅里叶红外光谱,分析重组GRSP对方解石型以及文石型碳酸钙晶体在形貌和晶型方面的影响;同时,利用沉淀法分析重组GRSP对碳酸钙结晶速度的影响以及与碳酸钙晶体的结合作用。结果表明,重组GRSP可诱导文石型碳酸钙晶体发生形貌变化,并对方解石型碳酸钙晶型产生影响。此外,重组GRSP表现出与碳酸钙结合的活性并能抑制方解石型碳酸钙晶体的结晶速度。上述结果表明,GRSP蛋白可能对贝壳的形成及发育具有重要影响并在贝壳肌棱柱层的形成中发挥重要作用。 相似文献
63.
Xuan Qi Li Prof. Zhiwei Feng Yinyan Xia Prof. Hua Chun Zeng 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(7):1945-1952
Calcium carbonate (CaCO3) is one of the most abundant and important biominerals in nature. Due to its biocompatibility, biodegradability and nontoxicity, CaCO3 has been investigated extensively in recent years for various fundamental properties and technological applications. Inspired by basic wall structures of cells, we report a protein‐assisted approach to synthesize CaCO3 into a double‐shelled structural configuration. Due to varying reactivities of outer and inner shells, the CaCO3 microcapsules exhibit different sorption capacities and various resultant structures toward different kinds of heavy metal ions, analogical to biologically controlled mineralization (BCM) processes. Surprisingly, three mineralization modes resembling those found in BCM were found with these bacterium‐like “CaCO3 cells”. Our investigation of the cytotoxicity (MTT assay protocol) also indicates that the CaCO3 microcapsules have almost no cytotoxicity against HepG2 cells, and they might be useful for future application of detoxifying heavy metal ions after further study. 相似文献
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65.
Synthesis of Ordered Biosilica Materials 总被引:3,自引:0,他引:3
Biogenic silica with amazing diversity of nanostructure shells,fibers and granules in diatoms and sponges is mediated by proteins and polysaccharides and forms at ambient pressure and temperatures.Chemical synthetic methods,in contrast,have to rely on extreme pH and /or surfactants to induce the condensation of silica precurors into specific patterns.One kind of benign synthesis method through plant cell wall template-directed ordered biosilica materials under ambient conditions in intriguing in this context.Organized silica materials in intercellular spaces of epidermal cells of tall fescue leaves were synthesized through molecular recognition between Si-OH and polysaccharide-OH or glycoprotein-OH of main components of plant cell walls and cellular processing as well when Si(OEt)4 was supplied rather than monosilicic acid.The biosynthesis of structural silica in tall fescue plant was correlated with the Si species applied,reflecting the slower condensation from tetraethoxysilane (TEOS) and thus providing greater opportunities for structural control by the underlying matrix of cell walls.The composition was estimated by energy dispersive X-ray(EDX) spectra on a scanning electron microscope.All organized structures showed carbon,oxygen and silicon peaks,indication that their formations differ from natural siliceous process. 相似文献
66.
The effect of concentration of structurally-different carboxylic acids such as ethylene diamine tetraacetic acid (H4edta), citric acid (H3cit), tartaric acid (H2tart), and acetic acid (HOAc) on growth and aggregation of calcium oxalate (CaOxa) in gel systems was comparatively investigated. H2tart and H3cit could change the morphology of cal- cium oxalate monohydrate (COM) and induce the formation of calcium oxalate dihydrate (COD). H4edta could induce the formation of COD at a lower concentration of 0.33 mmol/L and have the strongest ability to inhibit aggregation of COM. HOAc inhibited COM aggregation only at a higher concentration than 500 mmol/L. With increasing the number of carboxylic groups in an acid or increasing the concentration of carboxylic acid, the capacity of this acid to induce COD formation and to inhibit growth and aggregation of COM crystals increased. That is, this capacity followed the order: H4edta〉H3cit〉H2tart〉 〉HOAc. The result in this work suggested that the presence of H3cit and H2tart in urine played a role in the natural defense against stone formation. 相似文献
67.
Simulation of calcium oxalate stone in vitro 总被引:3,自引:0,他引:3
Urolithiasis constitutes a serious health problem that affects a significant section of mankind. Between 3% and 14% of the population, depending on the geographical region, suffer from this illness[1]. For example, the incidence of urolithiasis in Florida in the United States of America was 15.7 in 100000 people and increased to 20.8 in 1996. Urolithiasis remains a major medical prob-lem in China, especially in Guangdong Province. A survey in 1997 in Shenzhen City, the most southern city i… 相似文献
68.
Biomimetic growth of calcium phosphate over natural polymer may be an effective approach to constituting an organic/inorganic composite scaffold for bone tissue engineering. In this work, N-methylene phosphochitosan (NMPCS) was prepared via formaldehyde addition and condensation with phosphoric acid in a step that allowed homogeneous modification without obvious deterioration in chitosan (CS) properties. The NMPCS obtained was characterized by using FT-IR and elemental analysis. The macroporous scaffolds were fabricated through a freeze-drying technique. A comparative study on NMPCS and CS scaffold biomimetic mineralization was carried out in different media, i.e, a simulated body fluid (SBF) or alternative CaCl(2) and Na(2)HPO(4) solutions respectively. Apatite formation within NMPCS and CS scaffolds was identified with FT-IR, scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) and X-ray diffractometery (XRD). The results revealed alternate soaking of the scaffolds in CaCl(2) and Na(2)HPO(4) solutions was better than soaking in SBF solution alone in relation to apatite deposition on the scaffold pore walls. Biomineralization provides an approach to improve nature derived materials, e.g., chitosan derivative NMPCS properties e.g., compressive modulus, etc. SEM image of a NMPCS/apatite composite scaffold. 相似文献
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