Frincu M Crina, Fleming Sean D, Rohl Andrew L, Swift Jennifer A
Department of Chemistry, Georgetown University, 37th and O Streets NW, Washington, DC 20057-1227, USA.
J Am Chem Soc. 2004 Jun 30;126(25):7915-24. doi: 10.1021/ja0488030.
Epitaxial relationships between the surfaces of inorganic and bioorganic crystals can be an important factor in crystal nucleation and growth processes in a variety of biological environments. Crystalline cholesterol monohydrate (ChM), a constituent of both gallstone and atherosclerotic plaques, is often found in association with assorted mineral phases. Using in situ atomic force microscopy (AFM) and well-characterized model bile solutions, the nucleation and epitaxial growth of ChM on calcite (104) surfaces in real-time is demonstrated. The growth rates of individual cholesterol islands formed on calcite substrates were determined at physiological temperatures. Evidence of Ostwald's ripening was also observed under these experimental conditions. The energetics of various (104) calcite/(001) ChM interfaces were calculated to determine the most stable interfacial structure. These simulations suggest that the interface is fully hydrated and that cholesterol hydroxyl groups are preferentially positioned above carbonate ions in the calcite surface. This combination of experimental and theoretical work provides a clearer picture of how preexisting mineral seeds might provide a viable growth template that can reduce the energetic barrier to cholesterol nucleation under some physiological conditions.
在各种生物环境中，无机晶体与生物有机晶体表面之间的外延关系可能是晶体成核和生长过程中的一个重要因素。结晶一水合胆固醇（ChM）是胆结石和动脉粥样硬化斑块的组成成分，常与各种矿物相共存。利用原位原子力显微镜（AFM）和特性良好的模拟胆汁溶液，展示了ChM在方解石（104）表面的实时成核和外延生长。在生理温度下测定了方解石基底上形成的单个胆固醇岛的生长速率。在这些实验条件下还观察到了奥斯特瓦尔德熟化的证据。计算了各种（104）方解石/（001）ChM界面的能量，以确定最稳定的界面结构。这些模拟表明，界面完全水合，胆固醇羟基优先位于方解石表面的碳酸根离子上方。实验和理论工作的结合更清楚地说明了预先存在的矿物晶种如何提供一个可行的生长模板，从而在某些生理条件下降低胆固醇成核的能量障碍。
