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.

该子项目是利用资源的众多研究子项目之一 由 NIH/NCRR 资助的中心拨款提供。子项目的主要支持 并且子项目的主要研究者可能是由其他来源提供的， 包括其他 NIH 来源。 子项目可能列出的总成本 代表子项目使用的中心基础设施的估计数量， NCRR 赠款不直接向子项目或子项目工作人员提供资金。 尽管有广泛的证据表明在成型生物矿物的合成中使用无定形前体，但生物合成和稳定的机制仍然知之甚少。迄今为止的研究主要集中在添加剂和有机界面在提供瞬态稳定性方面的作用。然而，最近的一项研究表明，大量形成的无定形碳酸钙 (ACC) 颗粒在直径低于 70 nm 时似乎很稳定 [1]。亚稳定相与其结晶多晶型物相比具有较低的表面能，可以想象会导致阈值尺寸，低于该阈值尺寸，无定形形式实际上是最稳定的。在矿化细胞中，小囊泡很可能参与 ACC 合成、运输和储存，从而增加了额外的复杂性。囊泡的小尺寸（30-300 nm）、脂质表面化学和高曲率半径可能在通过调节表面相互作用实现稳定性方面发挥重要作用。在这里，我们使用体外系统，将水性钙盐封装在直径 0.1 - 1 微米的单层囊泡内，来研究这个问题。通过添加碳酸铵引发沉淀。初步的小角和广角 X 射线散射 (SAXS/WAXS) 数据表明 ACC 纳米粒子在 10 至 300 nm 范围内稳定至少 13 小时。为了扩展我们的分析，我们使用 SAXS 研究封装的 ACC 纳米颗粒的沉淀和聚集。与大量沉淀相反，以有限的离子浓度分离囊泡内的沉淀物提供了对晶体生长的独特控制。