DESY Photon Science, Deutsches Elektronen-Synchrotron DESY, Hamburg, 22607, Germany.
Center for Free-Electron Laser Science, Hamburg, 22607, Germany.
Sci Rep. 2020 Feb 4;10(1):1784. doi: 10.1038/s41598-020-58318-7.
Studies of biological systems typically require the application of several complementary methods able to yield statistically-relevant results at a unique level of sensitivity. Combined X-ray fluorescence and ptychography offer excellent elemental and structural imaging contrasts at the nanoscale. They enable a robust correlation of elemental distributions with respect to the cellular morphology. Here we extend the applicability of the two modalities to higher X-ray excitation energies, permitting iron mapping. Using a long-range scanning setup, we applied the method to two vital biomedical cases. We quantified the iron distributions in a population of macrophages treated with Mycobacterium-tuberculosis-targeting iron-oxide nanocontainers. Our work allowed to visualize the internalization of the nanocontainer agglomerates in the cytosol. From the iron areal mass maps, we obtained a distribution of antibiotic load per agglomerate and an average areal concentration of nanocontainers in the agglomerates. In the second application we mapped the calcium content in a human bone matrix in close proximity to osteocyte lacunae (perilacunar matrix). A concurrently acquired ptychographic image was used to remove the mass-thickness effect from the raw calcium map. The resulting ptychography-enhanced calcium distribution allowed then to observe a locally lower degree of mineralization of the perilacunar matrix.
研究生物系统通常需要应用几种互补的方法，这些方法能够在独特的灵敏度水平上产生具有统计学意义的结果。X 射线荧光和相衬技术的联合应用在纳米尺度上提供了极好的元素和结构成像对比。它们能够实现元素分布与细胞形态之间的稳健相关性。在这里，我们将这两种模式的适用性扩展到更高的 X 射线激发能量，从而允许进行铁成像。使用远程扫描设置，我们将该方法应用于两个重要的生物医学案例。我们定量分析了用针对结核分枝杆菌的氧化铁纳米容器处理的巨噬细胞群体中的铁分布。我们的工作使纳米容器聚集体在细胞质中的内化可视化。从铁的面质量图中，我们获得了每个聚集体中的抗生素负载分布和聚集体中纳米容器的平均面浓度。在第二个应用中，我们绘制了与人骨基质中骨陷窝（骨周基质）附近的钙含量的分布图。同时获得的相衬图像用于从原始钙图中去除质量厚度效应。由此产生的相衬增强钙分布使得能够观察到骨周基质局部矿化程度较低。
