Mapping Anti-Cancer Drugs using Advanced X-ray Microanalysis

描述（由申请人提供）：我们已经开发出一种原型X射线微量分析系统，具有前所未有的空间和光谱分辨率。它结合了两种最先进的仪器。一个是低温X射线微量热计，我们几年前在NASA的赞助下为X射线天文学任务建造的。第二种是FEI公司开发的高分辨率环境扫描电子显微镜（ESEM）。尽管微量热计在生物学上的应用似乎与天文学和天体物理学相去甚远，但它在广泛的能量范围内同时分辨X射线发射线的前所未有的能力已经提供了诱人的暗示，当与环境扫描电镜结合使用时，亚细胞尺度上异常丰富的化学信息。 到目前为止，我们已经对一些代表性的生物样品进行了原理验证测量。在0.2 keV至10 keV的能量范围内，微量热计的增加的光谱分辨率（2.5 - 6 eV）和随之而来的信号与背景比当前一代EDS（Si（Li）或锗）检测器至少提高了60倍。其在低X射线能量下的上级性能可以使ESEM在低电子能量和较低电子束电流下运行，从而最大限度地减少沉积到非常小体积中的功率，同时增强X射线图像分辨率和细胞诊断。在这些束条件下，与来自致密固体靶的发射强度相比，来自低密度生物样品的X射线产生相对较小。通过采用定制的X射线光学器件来显著增加X射线收集，我们打算补偿较低的X射线产生。 我们的计划是使用这种新的微量分析工具来全面研究一系列生物样品。反过来，准确的，相对元素丰度的测量可能成为常规和它们与离子转运，细胞增殖和凋亡的相关性可能导致细胞行为的强大诊断。在特定细胞位置发现的微量元素生物标志物可能被证明是疾病的可靠哨兵。以重元素为基础的化疗药物（如顺铂）的x射线光谱图像有望更好地了解抗癌药物的作用。高光谱分辨率可能使人们有可能选择蛋白质标记物从一个更生物相关的元素，而不是从重元素所需的日期为高对比度电子显微镜。这将大大简化样品制备，保持细胞完整性并最大限度地减少图像中的伪影。我们期望获得大量关于细胞行为的新信息，以及其早期癌症检测诊断潜力的迹象。

DESCRIPTION (provided by applicant): We have developed a prototype x-ray microanalysis system with unprecedented spatial and spectroscopic resolution. It combines two state-of-the art instruments. One is a cryogenic x-ray microcalorimeter that we built several years ago for x-ray astronomy missions under NASA auspices. The second is a high resolution, environmental scanning electron microscope (ESEM) developed by the FEI Company. Although the microcalorimeter's application to biology may seem far afield from astronomy and astrophysics, its unprecedented power to simultaneously resolve x-ray emission lines over a broad range of energies has already provided tantalizing hints of unusually rich chemical information at sub-cellular dimensions when operating in conjunction with the ESEM. To date, we have conducted proof-of-principle measurements on a few representative biological samples. The increased spectral resolution (2.5 - 6 eV) and consequent signal-to back ground ratio of the microcalorimeter over the energy range of 0.2 keV to 10 keV is at least a 60-fold improvement over present generation EDS (Si(Li) or germanium) detectors. Its superior performance at low x-ray energies could enable ESEM operation at low electron energies and lower electron beam current, thereby minimizing the power deposited into very small volumes while enhancing x-ray image resolution and cellular diagnostics. Under these beam conditions, the x-ray production from low density biological samples is relatively small compared to the emission intensity from dense solid targets. By employing a custom-made, x-ray optic to significantly increase x-ray collection, we intend to compensate for lower x-ray production. Our plan is to use this new microanalytical tool to comprehensively study a range of biological samples. In turn, accurate, relative elemental abundance measurements could become routine and their correlation with ion transport, cell proliferation, and apoptosis could lead to powerful diagnostics of cellular behavior. Trace element biomarkers found at specific cellular locations may prove to be reliable sentinels of disease. Spectroscopic x-ray images of heavy element-based chemotherapy drugs such as cisplatin promise better understanding of the actions of anti-cancer drugs. High spectral resolution may make it possible to choose protein markers from a more biologically relevant set of elements, rather than from the heavy-elements needed to date for high contrast electron microscopy. This would greatly simplify sample preparation, maintain cell integrity and minimize artifacts in the image. We expect to have an incredible wealth of new information about cellular behavior and indications of its diagnostic potential for early cancer detection.