Fundamental Mass Spectrometry Measurements of Electrosprayed and Matrix-Assisted Laser Desorbed Ions Using an Improved Superconducting Tunnel Junction Detector

Mark E.Bier教授和他在卡内基梅隆大学的学生得到了美国国家科学基金会化学系化学测量和成像(CMI)计划的支持，他们将针对质谱学(MS)改进的检测器进行基础研究，MS是表征化学品和生物化学品的主要工具。数据和检测器技术的最新进展使得在MS分析过程中检测离子时的响应速度和能量分辨率都得到了提高。比尔小组正在调查，当离子撞击探测器时，对沉积能量的测量是否与离子的结构有关--这是理解分子功能的关键信息。例如，这可以改进对大分子复合体的化学分析，如病毒颗粒和合成纳米颗粒。可能的应用跨越了许多学科，包括化学、生物、物理、聚合物科学、医学和材料科学，这使得新的检测器具有潜在的商业化吸引力。参与研究的学生将接触到多学科的研究，包括劳伦斯利弗莫尔国家实验室的低温物理培训。为了能够进行这些气相离子化学测量，超导隧道结(STJ)低温探测器正在通过增加像素的大小和数量而得到改进，从而使探测面积扩大了10倍。正在对钽-STJ和Nb-STJ进行研究。探测器正在与先进的高速电子设备相结合，以改进到达时间和能量测量，并在两个质谱仪上进行测试：配备基质辅助激光解吸电离(MALDI)的飞行时间分析器和配备MALDI和电喷雾电离(ESI)的高m/z离子陷阱。这应该能够基于亚稳态碎裂产生质谱图。这项研究正在探索能量响应在测量形状(例如，天然蛋白质)和密度(例如，金纳米颗粒)方面是否具有额外的分析用途。STJ能量分辨率的提高和分析较大大分子的能力可能会导致MS测量的范式转变，特别是在聚合物和小颗粒和大纳米颗粒研究领域。随后应该有关于ESI和MALDI的新的基本知识，从而更好地了解各自的高m/z限制。

Professor Mark E. Bier and his students at Carnegie Mellon University are supported by the Chemical Measurement and Imaging (CMI) Program of the Division of Chemistry at the NSF to conduct fundamental studies targeting improved detectors for mass spectrometry (MS, a major tool for characterizing chemicals and biochemicals). Recent advances in data and detector technologies have enabled improvements in both the speed of response and energy resolution attainable when detecting ions during MS analysis. The Bier group is investigating whether measurement of the energy deposited when an ion impacts a detector can be related to the structure of the ion - information critical for understanding how molecules function. This could enable, for example, improved chemical analysis of macromolecular complexes such as virus particles and synthetic nanoparticles. Possible applications span many disciplines, including chemistry, biology, physics, polymer science, medicine and materials science, making the new detector potentially attractive for commercialization. Students involved are exposed to multidisciplinary research, including training in low-temperature physics at Lawrence Livermore National Laboratory. To enable these gas phase ion chemistry measurements, superconducting tunnel junction (STJ) cryodetectors are being improved by increasing the size and number of pixels, resulting in a 10X larger detection area. Both tantalum-STJs and niobium-STJs are being investigated. The detectors are being combined with advanced high-speed electronics to improve arrival time and energy measurements, and tested on two mass spectrometers: a time-of-flight analyzer equipped with matrix-assisted laser desorption ionization (MALDI) and a high m/z ion trap equipped with both MALDI and electrospray ionization (ESI). This should enable generation of mass spectra based on metastable fragmentation. The research is exploring whether the energy response has additional analytical utility in the measurement of shape (e.g., of native proteins) and density (e.g., for gold nanoparticles). The improved energy resolution of STJs and their ability to analyze larger macromolecules could result in a paradigm shift for MS measurements, especially in the fields of polymer and small and large nanoparticle research. New fundamental knowledge about ESI and MALDI should ensue, providing better insight into the respective high m/z limits.