VIBRATIONALLY COOLED MATRIX-ASSIST LASER DESORPTION/IONIZATION FT MASS SPECTROM

振动冷却基质辅助激光解吸/电离 FT 质谱

• 批准号: 7601951
• 负责人: PETER B. O'CONNOR
• 金额: $ 3.88万
• 依托单位: BOSTON UNIVERSITY MEDICAL CAMPUS
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-08-03 至 2008-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7601951
• 关键词: Aluminum; Area; Articular Range of Motion; Automation; Back; Caliber; Cardiovascular system; Collaborations; Compatible; Computer Retrieval of Information on Scientific Projects Database; Copper; Diffusion; Electronics; Fourier Transform; Funding; Grant; Hardness; Heating; Image; Institutes; Institution; Language; Lasers; Libraries; Link; Lubrication; Magnetism; Motor; Noise; Numbers; Oils; Optics; Performance; Personal Satisfaction; Positioning Attribute; Programming Languages; Proteomics; Pump; Range of motion exercise; Rate; Research; Research Personnel; Resources; Robot; Route; Sampling; Signal Transduction; Slide; Source; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Speed; Spottings; Staging; Stainless Steel; Standards of Weights and Measures; Surface; System; Testing; Time; Torque; Translations; Travel; United States National Institutes of Health; Vacuum; Vent; Visual; Work; base; cryogenics; design; design and construction; evaluation/testing; improved; mass spectrometer; pressure; prevent; research study; size; two-dimensional; vapor; virtual

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The improvement and optimization of the Vibrationally Cooled MALDI-FTMS continues. This year we carried out further testing an evaluation of the XY stage that was designed and constructed in collaboration with the Fraunhofer Institute. This stage is a critical component for full automation of the MALDI-FTMS. The design parameters for this stage were defined to handle the typical proteomic type sample. Many proteomic experiments use robots that are designed to work with microtiter plates which are ~76 x 89 mm in size. Therefore, the stage was required to have full travel of at least 100 x 100 mm. For the MALDI Fourier transform mass spectrometer used, the travel time from spot to spot is not the limiting factor in the experiment speed, so a travel of 2 mm/sec was defined as it would allow the stage to position to the next spot 1 mm away in 0.5 seconds. The positioning accuracy was defined to be 1 um, which is much more accurate than is needed for the standard MALDI experiment in which the laser beam spot is often 50 um diameter, but will allow the stage to be used in a MALDI imaging mode. Aside from this, the stage had to be truly vacuum compatible, had to be mounted vertically, and to generate no detectable RF interference noise, and had to take up minimal space so that the vacuum chamber could be made as small as possible for improved pumping performance. The two-dimensional stage is a single block design with the two axis motors, linear encoders, and position switches all integrated into the central block. The system uses ballscrews and crossed roller bearings which will require minimal lubrication in vacuum; what little lubrication is needed is provided by low vapor pressure diffusion pump oil. In order to build the motors into this block, they are mounted on copper brackets (to dump their heat into the block which acts as a heat sink) and pulleys are used to transfer their torque to the ballscrew. The belts for these pulleys are actually small electrowelded stainless steel bands, and in order to keep them centered on the pulleys, the pulley wheels are ground to be slightly concave. Tensioning set screws are mounted into the block to allow the pulleys to be tightened properly during testing. In order to prevent over determination of the position of the ballscrew, it is mounted in two places only: the pulley bearing assembly and the plate. The stage itself is designed in three pieces, an upper and lower plate, and the central block. The motors, limit switches, and linear encoder electronics are all mounted (and heat sinked) to the central block. The linear encoder slides are mounted to the upper and lower plates. The three pieces are black anodized to improve surface hardness, but even more importantly, to improve radiative cooling of the blocks. All wire routes are also contained within the block. The motors and electronics dump their heat loads into the central block, which is only able to dissipate that heat through conductive cooling at the bearings and radiative cooling. The conductive cooling is very inefficient since the bearings are stainless steel (very low heat transfer capacity) and the contact area is very low. A copper band or braid was considered for improving the conductive heat transfer rate, but a quick calculation of the heat transfer of such a band compared to the radiative cooling rate showed that the heat transfer through the copper band was negligible. There are several positioning screws for the crossed roller bearings, wire traces, and bolt holes for mounting the motors, bearings, and electronics. All of these holes are vented to minimize virtual leaks. The system uses four position encoders, two linear encoders for determining position, and two rotary encoders mounted on the back of the motors for determining velocity. The system uses optical limit switches. The switch is a photodiode/phototransistor pair mounted on the central stage body which is interrupted by an aluminum flag mounted on the upper and lower stage plates. Two such switches are mounted for each axis. When the stage moves to the end of its range of motion, this flag blocks the photodiode's signal to the phototransistor, and the electronics signal the stage to stop. Such a system, while similar to a rocker switch or magnetic switch involves fewer parts and greater positioning accuracy. The sample translation stage requires a large number of vacuum electrical feedthroughs (46) to control 2 motors, 4 encoders, 4 limit switches, and a thermocouple. Furthermore, because this is being mounted on an FTMS which has high sensitivity to RF interference noise, it was critical that the feedthrough and cables be well shielded. The vacuum chamber for this sample translation stage was designed to be as small as possible (for efficient pumpdown) but large enough to allow the full range of motion for the stage. The sample translation stage control was developed as a set of commands that can be called from a dynamically linked library (dll) in any Microsoft window's based programming language. The language used here was C++ as implemented in Microsoft Visual C++, version 6. A copy of the stage has now been constructed for use with the cryogenic FTMS being assembled within the BUSM Cardiovascular Proteomics Center.

该子项目是利用该技术的众多研究子项目之一 资源由 NIH/NCRR 资助的中心拨款提供。子项目和 研究者 (PI) 可能已从 NIH 的另一个来源获得主要资金， 因此可以在其他 CRISP 条目中表示。列出的机构是 对于中心来说，它不一定是研究者的机构。 振动冷却 MALDI-FTMS 的改进和优化仍在继续。 今年，我们对与弗劳恩霍夫研究所合作设计和建造的 XY 平台进行了进一步测试和评估。 该阶段是 MALDI-FTMS 完全自动化的关键组件。 该阶段的设计参数被定义为处理典型的蛋白质组类型样品。 许多蛋白质组实验使用的机器人被设计用于使用尺寸约为 76 x 89 毫米的微量滴定板。 因此，要求平台的全行程至少为 100 x 100 毫米。 对于所使用的 MALDI 傅立叶变换质谱仪，从一个点到另一个点的行程时间并不是实验速度的限制因素，因此将行程定义为 2 毫米/秒，因为它允许载物台在 0.5 秒内定位到 1 毫米外的下一个点。 定位精度定义为 1 um，这比标准 MALDI 实验所需的精度要高得多，其中激光束光斑的直径通常为 50 um，但允许在 MALDI 成像模式下使用平台。 除此之外，该平台必须真正真空兼容，必须垂直安装，并且不能产生可检测到的射频干扰噪声，并且必须占用最小的空间，以便真空室可以做得尽可能小，以提高泵送性能。 二维平台采用单块设计，两轴电机、线性编码器和位置开关全部集成到中央块中。 该系统使用滚珠丝杠和交叉滚子轴承，在真空中需要最少的润滑；低蒸气压扩散泵油提供了所需的少量润滑。 为了将电机内置到该模块中，它们被安装在铜支架上（将热量转移到充当散热器的模块中），并使用滑轮将其扭矩传递到滚珠丝杠。 这些滑轮的皮带实际上是小型电焊不锈钢带，为了使它们保持在滑轮的中心，滑轮被磨成稍微凹形。 张紧固定螺钉安装在滑​​轮组中，以便在测试过程中正确拧紧滑轮。 为了防止过度确定滚珠丝杠的位置，它仅安装在两个地方：滑轮轴承组件和板。 舞台本身设计为三部分，上板、下板以及中央块。 电机、限位开关和线性编码器电子设备均安装（并散热）到中央块。 线性编码器滑块安装在上板和下板上。 这三个部件均经过黑色阳极氧化处理，以提高表面硬度，但更重要的是，改善块体的辐射冷却。 所有线路也包含在该块内。 电机和电子设备将其热负荷转移到中央块中，中央块只能通过轴承处的传导冷却和辐射冷却来散发热量。 由于轴承是不锈钢的（传热能力非常低）且接触面积非常小，传导冷却效率非常低。 考虑使用铜带或编织物来提高传导传热速率，但与辐射冷却速率相比，对这种带的传热进行快速计算表明，通过铜带的传热可以忽略不计。 有多个用于交叉滚子轴承的定位螺钉、导线以及用于安装电机、轴承和电子设备的螺栓孔。 所有这些孔均经过通风，以最大限度地减少虚拟泄漏。 该系统使用四个位置编码器，两个用于确定位置的线性编码器，以及安装在电机背面的两个旋转编码器用于确定速度。 该系统使用光学限位开关。 该开关是安装在中央载物台主体上的光电二极管/光电晶体管对，其被安装在上下载物台板上的铝旗中断。 每个轴安装两个这样的开关。 当载物台移动到其运动范围的末端时，该标志会阻止光电二极管向光电晶体管发出的信号，并且电子设备会向载物台发出停止信号。 这种系统虽然类似于摇杆开关或磁性开关，但涉及的零件更少，定位精度更高。 样品平移台需要大量真空电气馈通 (46) 来控制 2 个电机、4 个编码器、4 个限位开关和一个热电偶。 此外，由于它安装在对射频干扰噪声具有高敏感性的 FTMS 上，因此馈通件和电缆的良好屏蔽至关重要。 该样品平移台的真空室设计得尽可能小（以实现高效抽气），但又足够大以允许该台进行全方位的运动。 示例翻译阶段控件被开发为一组命令，可以从任何基于 Microsoft Windows 的编程语言的动态链接库 (dll) 调用。 这里使用的语言是在 Microsoft Visual C++ 版本 6 中实现的 C++。现已构建了阶段的副本，用于与 BUSM 心血管蛋白质组中心内组装的低温 FTMS 一起使用。