Ortega Eduardo, Cantu-Valle Jesús, Plascencia-Villa Germán, Vergara Sandra, Mendoza-Santoyo Fernando, Londono-Calderon Alejandra, Santiago Ulises, Ponce Arturo
Department of Physics and Astronomy, The University of Texas at San Antonio, One UTSA Circle, San Antonio, Texas 78249.
Microsc Res Tech. 2017 Dec;80(12):1249-1255. doi: 10.1002/jemt.22923. Epub 2017 Aug 11.
In the current work, irregular morphology of Staphylococcus aureus bacteria has been visualized by phase retrieval employing off-axis electron holography (EH) and 3D reconstruction electron tomography using high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM). Bacteria interacting with gold nanoparticles (AuNP) acquired a shrunken or irregular shape due to air dehydration processing. STEM imaging shows the attachment of AuNP on the surface of cells and suggests an irregular 3D morphology of the specimen. The phase reconstruction demonstrates that off-axis electron holography can reveal with a single hologram the morphology of the specimen and the distribution of the functionalized AuNPs. In addition, EH reduces significantly the acquisition time and the cumulative radiation damage (in three orders of magnitude) over biological samples in comparison with multiple tilted electron expositions intrinsic to electron tomography, as well as the processing time and the reconstruction artifacts that may arise during tomogram reconstruction.
在当前工作中，通过采用离轴电子全息术（EH）进行相位恢复以及使用高角度环形暗场扫描透射电子显微镜（HAADF-STEM）进行三维重建电子断层扫描，已观察到金黄色葡萄球菌细菌的不规则形态。由于空气脱水处理，与金纳米颗粒（AuNP）相互作用的细菌呈现出收缩或不规则的形状。STEM成像显示AuNP附着在细胞表面，并表明样品具有不规则的三维形态。相位重建表明，离轴电子全息术可以通过单个全息图揭示样品的形态和功能化AuNP的分布。此外，与电子断层扫描固有的多次倾斜电子曝光相比，EH显著减少了对生物样品的采集时间和累积辐射损伤（降低了三个数量级），以及断层扫描重建过程中可能出现的处理时间和重建伪像。
