SYNTHESIS AND AGGREGATION OF CALCIUM CARBONATE IN PHOSPHOLIPID VESICLES

磷脂囊泡中碳酸钙的合成和聚集

• 批准号: 8361302
• 负责人: Derk Joester
• 金额: $ 1.18万
• 依托单位: ILLINOIS INSTITUTE OF TECHNOLOGY
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-01-01 至 2011-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8361302
• 关键词: Biological; Biophysics; Calcium; Calcium Carbonate; Caliber; Cells; Chemistry; Data; Encapsulated; Funding; Grant; Growth; Hour; In Vitro; Ions; Lead; Lipids; National Center for Research Resources; Phase; Phospholipids; Play; Precipitation; Principal Investigator; Radial; Research; Research Infrastructure; Resources; Role; Salts; Shapes; Source; Surface; System; United States National Institutes of Health; Vesicle; ammonium carbonate; aqueous; cost; nanoparticle; neutrophil; particle

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Although there is widespread evidence for the use of amorphous precursors in the synthesis of shaped biominerals, the mechanisms of biological synthesis and stabilization remain poorly understood. Research to date has focused largely on the role of additives and organic interfaces in providing transient stabilization. A recent study indicates, however, that amorphous calcium carbonate (ACC) particles formed in bulk appear to be stable below a diameter of 70 nm [1]. The lower surface energy of a meta-stable phase compared to itscrystalline polymorphs could conceivably lead to a threshold size below which the amorphous form is actually the most stable. In mineralizing cells, small vesicles are very likely involved in ACC synthesis, transport, and storage, adding an additional layer of complexity. The small size of the vesicles (30-300 nm), the lipid surface chemistry, and the high radius of curvature may each play an essential role in achieving stability by modulating surface interactions. Here we use an in vitro system, aqueous calcium salts encapsulated within 0.1 - 1 micron diameter unilamellar vesicles, to study this problem. Precipitation is initiated by addition of ammonium carbonate. Preliminary small and wide angle x-ray scattering (SAXS/WAXS) data indicate stabilization of ACC nanoparticles in the range from 10 to 300 nm for at least 13 hours. To extend our analysis, we use SAXS to study precipitation and aggregation of encapsulated ACC nanoparticles. In contrast to bulk precipitation, isolation of the precipitates inside vesicles with limited ion concentration offers a unique control over crystal growth.

这个子项目是利用资源的许多研究子项目之一。 由NIH/NCRR资助的中心拨款提供。对子项目的主要支持 子项目的首席调查员可能是由其他来源提供的， 包括美国国立卫生研究院的其他来源。为子项目列出的总成本可能 表示该子项目使用的中心基础设施的估计数量， 不是由NCRR赠款提供给次级项目或次级项目工作人员的直接资金。 虽然有广泛的证据表明非晶态前驱体用于合成成型生物矿物，但生物合成和稳定的机制仍然知之甚少。到目前为止，研究主要集中在添加剂和有机界面在提供暂态稳定方面的作用。然而，最近的一项研究表明，大量形成的无定形碳酸钙颗粒在直径70 nm以下似乎是稳定的[1]。亚稳相的表面能比晶态低，这可能会导致一个阈值尺寸，低于这个阈值时，非晶态实际上是最稳定的。在矿化细胞中，小囊泡很可能参与ACC的合成、运输和储存，从而增加了一层额外的复杂性。囊泡的小尺寸(30-300 nm)、脂质的表面化学和高的曲率半径都可能在通过调节表面相互作用来实现稳定性方面发挥重要作用。在这里，我们使用一个体外系统，包裹在0.1-1微米直径的单层囊泡中的水钙盐，来研究这个问题。通过加入碳酸铵开始沉淀。初步的小角和广角X射线散射(SAXS/WAXS)数据表明，ACC纳米颗粒在10到300 nm的范围内稳定至少13小时。为了扩展我们的分析，我们使用SAXS研究了包裹的ACC纳米颗粒的沉淀和聚集。与整体沉淀不同，在离子浓度有限的情况下，分离囊泡内的沉淀物提供了对晶体生长的独特控制。