同步輻射軟X光斷層掃描顯微技術

Synchrotron-based Microscopy on Soft X-ray Tomography

軟X光斷層掃描顯微術（soft X-ray tomography, SXT）是近幾年發展出來的新影像技術，是全場穿透式的顯微鏡。光束線能量範圍在0.26～2.6 keV，為台灣光子源第二期週邊實驗設施的第一座光束線，建立於台灣光子源24號出口處（TPS 24A）。一般生物體為含碳、氫、氮、氧等元素的化合物，而生物體大多需在水溶液下才有活性，因此軟X光能量介於碳元素與氧元素之K層吸收（284～543 eV，水窗能量）下，對水溶液下的生物體有強烈的X光吸收對比（absorption contrast），可穿透約10μm的生物厚度。而較高能量（～2.6 keV）的軟X光對水溶液下的生物體則有強烈的X光相位對比（phase contrast），可穿透約50μm的生物厚度。因此軟X光斷層掃描顯微術對較厚的生物細胞和組織可在不需染色與切薄片的情況下，快速的量測細胞内部胞器與組織精細的三維原生結構影像。此影像技術於二維生物影像解析度可達15-30 nm，三維生物影像解析度約50 nm，此技術亦將結合螢光顯微術，觀察生物細胞内在同一位置的結構與功能關連性。在科學研究上可探討細胞內錯誤摺疊的蛋白質堆積引起的神經退化性疾病、細胞胞器結構的變化造成生理和病理的疾病、探討細胞與細胞之間的交互作用以及研究微生物、病毒、細菌與宿主細胞的作用等，以開拓生物醫學新領域並提供藥物研究、疾病機制探討、醫學研發等相關的研究。

Soft X-ray tomography (SXT) is a newly developed imaging technique with a full-field transmission microscopy. The beamline is located at Taiwan Photon Source port 24 (TPS 24A). SXT beamline covers the energy range of 0.26~2.6 ke V, which including the water window of 284~543 eV is dedicated to image frozen-hydrated biological specimen in native state in biomedical researches. The spatial resolution of this beamline has achieved to 15~30 nm for 2D imaging, and we expect to achieve 50 nm for 3D tomography. SXT technique is possible to apply in some scientific subjects, such as the aggregation of misfolded proteins in cells for neurodegenerative disease, shape changes of sub-cellular organelles in cells for disease study, cell-cell interaction and communication and virus or bacteria interaction with host-cells. Moreover, it is possible to explore the investigation to a drug development, screening and disease mechanism.