Development of ZnTe Powder Phosphor for Protein Crystallographic X-ray Detectors

蛋白质晶体X射线探测器用ZnTe荧光粉的研制

• 批准号: 7682855
• 负责人: Christopher J. Summers
• 金额: $ 35.44万
• 依托单位: PHOSPHORTECH
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-03-15 至 2011-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7682855
• 关键词: Air; Aluminum Oxide; Amino Acids; Area; Cereals; Chemicals; Collaborations; Communities; Crystallography; Development; Digital Radiography; Discipline; Environment; Europe; Exhibits; Film; Financial Support; Goals; Image; Light; Marketing; Measurement; Medical; Methionine; Molecular Biology; Motivation; Output; Oxygen; Performance; Phase; Powder dose form; Problem Solving; Procedures; Process; Proteins; Reaction Time; Roentgen Rays; Sales; Sampling; Selenium; Signal Transduction; Structure; Sulfur; Synchrotrons; System; Technology; Tellurium; Time; United States National Institutes of Health; Water; Work; Zinc; absorption; base; beamline; bioimaging; capsule; design; detector; experience; gadolinium sulfoxylate; improved; light emission; meetings; oxidation; physical property; prevent; public health relevance; scale up; seal; success; zinc selenide

DESCRIPTION (provided by applicant): We propose to continue development of a new, high-performance X-ray phosphor, based on zinc telluride (ZnTe), doped with oxygen. Currently, our phosphor is at least 3-fold brighter than present technology and further improvements are expected in Phase II. This increase in brightness will solve a major problem in the design of these detector systems. Simply stated: ZnTe:O will have a major impact on protein crystallography. Our project will be most valuable to this major field, which is extremely important to NIH. Every synchrotron beamline, assigned to structural molecular biology (there are ~20 of these), has a detector, for which NIH has already paid ~$1million. Our phosphor will improve the performance of each of these substantially. PhosphorTech Corporation (PTC) is highly experienced in this area. In 2002 we developed ZnSe:Cu,Ce, a zinc selenide (ZnSe)-based phosphor, in collaboration with Bruker-AXS Inc., for use as an X-ray screen phosphor in their chemical crystallography detector system "Apex." ZnSe:Cu,Ce has proven to be an outstanding phosphor for this application, being about 3x brighter than Gd2O2S:Tb the "standard" phosphor for CCD crystallographic detectors. ZnSe:Cu,Ce exhibits a time response (afterglow) considerably faster than Gd2O2S:Tb, which is another positive feature. Bruker AXS now dominates the chemical crystallography market in the USA and Europe, with over 85% market share. This is in part due to the remarkable success of our phosphor, and the strong acceptance of this phosphor by Bruker customers. PTC supplies this phosphor to Bruker through commercial sales and thus the contribution of PTC to chemical crystallography has been profound. We propose in this project to make an equally profound contribution to another scientific discipline structural molecular biology. However, detectors used for protein crystallography cannot use ZnSe:Cu,Ce phosphor because it contains selenium (Se). Protein crystallographers today solve their structures by "multiple energy anomalous dispersion" (MAD) phasing methods1,2. About 80% of these studies make use of Se, chemically replacing sulfur in the amino acid methionine, as the atom providing this anomalous scattering signal. Since Se in the ZnSe:Cu,Ce phosphor will manifest the same discontinuous change in its X-ray absorption spectrum as the Se in the protein crystal sample, at precisely the same X-ray energy (12,658eV), it is inappropriate for the detector used in these measurements to contain Se. ZnTe has very similar chemical and physical properties as ZnSe. The two zinc-blend structures have virtually the same lattice constant of 6.1037E, and similar band gaps (2.3eV for ZnTe; 2.7eV for ZnSe). But the absorption edges of tellurium (4,341eV, 31,814eV) are far away from the selenium edge. Thus, in addition to higher efficiency, there is a strong motivation to produce ZnTe phosphor powders that can be used to make large screens for imaging the diffraction of protein crystals. We have completely met our Phase I goals. We fabricated a ZnTe-based phosphor, ZnTe:O, that is as bright (and could potentially be brighter) than our ZnSe phosphor. We have also established fabrication procedures that seal the ZnTe:O phosphor from the outside environment, thus preventing its oxidative degradation that was the original problem for this project. The light emission of our ALD- coated ZnTe:O phosphor is now time-independent and compatible with commercial screen processes. We therefore propose, during Phase II of this project, to develop the means to synthesize larger quantities of high quality ZnTe:O phosphor powder, and optimize the large screens necessary for protein crystallography CCD detectors. ZnTe:O phosphor converting films will be most useful for protein crystallography detectors used at synchrotron beamlines, enhancing their value to NIH and to the molecular biology community as a whole. In addition, the improved performance of this phosphor also promises to have other valuable applications in biomedical imaging. PUBLIC HEALTH RELEVANCE: The proposed ZnTe:O phosphor material will have significant applications in protein crystallography detectors used at synchrotron beamlines, as well as digital radiography applications, enhancing its value to the NIH and to the molecular biology and medical communities as a whole.

描述（由申请人提供）：我们建议继续开发一种新的，高性能的x射线荧光粉，基于碲化锌（ZnTe），掺杂氧气。目前，我们的荧光粉的亮度至少是现有技术的3倍，预计在第二阶段将进一步改进。这种亮度的增加将解决这些探测器系统设计中的一个主要问题。简单地说：ZnTe:O将对蛋白质晶体学产生重大影响。我们的项目将对这个对NIH极其重要的专业领域最有价值。分配给结构分子生物学的每条同步加速器光束线（大约有20条）都有一个探测器，NIH已经为此支付了大约100万美元。我们的荧光粉将大大提高它们的性能。磷科技公司（PTC）在这一领域经验丰富。2002年，我们与Bruker-AXS公司合作开发了ZnSe:Cu，Ce，一种硒化锌（ZnSe）基荧光粉，用于其化学晶体学探测器系统“Apex”中的x射线屏幕荧光粉。ZnSe:Cu，Ce已被证明是一种出色的荧光粉，其亮度约为CCD晶体探测器“标准”荧光粉Gd2O2S:Tb的3倍。ZnSe:Cu，Ce表现出比Gd2O2S:Tb更快的时间响应（余辉），这是另一个积极的特征。布鲁克AXS目前在美国和欧洲的化学晶体学市场占据主导地位，市场份额超过85%。这部分是由于我们的荧光粉取得了显著的成功，以及布鲁克客户对这种荧光粉的强烈接受。PTC通过商业销售向布鲁克提供这种荧光粉，因此PTC对化学晶体学的贡献是深远的。我们建议在这个项目中对另一个科学学科结构分子生物学做出同样深刻的贡献。然而，用于蛋白质晶体学的探测器不能使用ZnSe:Cu，Ce荧光粉，因为它含有硒（Se）。目前，蛋白质晶体学家通过“多能反常色散”（MAD）相位方法来解决蛋白质结构问题1,2。在这些研究中，大约80%的研究使用硒作为提供这种异常散射信号的原子，硒在化学上取代了氨基酸蛋氨酸中的硫。由于在完全相同的x射线能量（12,658eV）下，ZnSe:Cu，Ce荧光粉中的Se在其x射线吸收光谱中表现出与蛋白质晶体样品中的Se相同的不连续变化，因此在这些测量中使用的探测器不适合含有Se。ZnTe与ZnSe具有非常相似的化学和物理性质。这两种锌共混结构具有几乎相同的晶格常数6.1037E和相似的带隙（ZnTe为2.3eV， ZnSe为2.7eV）。而碲（4,341eV, 31,814eV）的吸收边则远离硒的吸收边。因此，除了更高的效率之外，有强烈的动机生产ZnTe荧光粉，这种荧光粉可用于制造用于成像蛋白质晶体衍射的大屏幕。我们已经完全达到了第一阶段的目标。我们制造了一种基于ZnTe的荧光粉，ZnTe:O，它和我们的ZnSe荧光粉一样亮（并且可能更亮）。我们还建立了制造程序，将ZnTe:O荧光粉与外部环境隔离，从而防止其氧化降解，这是该项目的原始问题。我们的ALD涂层ZnTe:O荧光粉的发光现在是时间无关的，并与商业屏幕工艺兼容。因此，我们建议在该项目的第二期中，开发大量合成高质量ZnTe:O荧光粉的方法，并优化蛋白质晶体学CCD探测器所需的大屏幕。ZnTe:O荧光粉转换膜将在同步加速器光束线上用于蛋白质晶体学探测器，提高其对美国国立卫生研究院和整个分子生物学社区的价值。此外，这种荧光粉的性能也有望在生物医学成像中有其他有价值的应用。