TOWARD UNDERSTANDING MECHANISM OF MALDI PROCESS

理解MALDI过程的机制

• 批准号: 7369033
• 负责人: MICHAEL A BALDWIN
• 金额: $ 0.11万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN FRANCISCO
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-03-01 至 2007-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7369033
• 关键词: TOWARD; UNDERSTANDING; MECHANISM; MALDI; PROCESS

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. Mass spectrometry is the paramount technique for the detection, analysis and identification of biological macromolecules such as proteins, glycoconjugates and nucleic acids. Ionization techniques for involatile materials are key to the success of mass spectrometry in biology and medicine. Matrix assisted laser desorption/ionization (MALDI) is one such method but the fundamental mechanism of this method is only poorly understood. Further development of the MALDI technique will be dependent upon the identification of new matrix materials with properties that may not have been fully appreciated or exploited before now. Initially we investigated the use of explosives as new matrices that would impart additional energy to the analyte upon laser irradiation, thereby increasing the sensitivity of detection. Upon detonation, explosives release large amounts of gas. Consequently we are now developing a new theory of MALDI as a thermal process in which CO2 is released by laser irradiation of carboxylic acid matrices, resulting in a phenomenon we describe as "pneumatic assistance". We are developing mass and heat transfer equations that model the matrix composition, the degree of melting and pyrolysis, and the amount of gas in the melt at any time and at any depth during or after the typical 3 ns pulse from a nitrogen laser at 337 nm. Gas diffusion will result in bubble formation, growth, eventual bursting and sputtering of molten matrix entraining analyte ions formed during crystallization. The equations rely on macroscopic properties of the matrix and its decarboxylation product, and will calculate and predict a temporal and spatial model of the following: -Absorption of laser radiation by the matrix, with some loss of energy by fluorescence. - The effects of heating, melting, decarboxylation and subsequent cooling after the laser pulse. - Super-saturation of molten matrix and the decarboxylation product with CO2. - Genesis, growth and bursting of bubbles in the melt, and the flight of fragments as a plume of droplets. - Competing loss of analyte ions by recombination of ion pairs and single ions, both in the body of the melt and in flying microdroplets of the plume. - Partial or total evaporation of the matrix and its decarboxylation product from the analyte ions. Predictions made by the computer model are being compared with experimental MALDI data. (Additional effort and instrument time reported under Collaborative projects and other Technical Research and Development projects.)

该子项目是利用NIH/NCRR资助的中心赠款提供的资源的许多研究子项目之一。子项目和研究者（PI）可能从另一个NIH来源获得主要资金，因此可以在其他CRISP条目中表示。所列机构为中心，不一定是研究者所在机构。质谱是检测、分析和鉴定生物大分子如蛋白质、糖缀合物和核酸的最重要技术。非挥发性物质的电离技术是生物学和医学质谱分析成功的关键。基质辅助激光解吸/电离（MALDI）就是这样一种方法，但这种方法的基本机制知之甚少。MALDI技术的进一步发展将取决于新基质材料的鉴定，这些材料的特性在此之前可能还没有被充分认识或利用。最初，我们研究了使用炸药作为新的矩阵，将赋予额外的能量的分析物激光照射后，从而增加检测的灵敏度。爆炸时，炸药会释放出大量的气体。因此，我们现在正在开发一个新的理论MALDI作为一个热过程，其中CO2是由激光照射的羧酸矩阵，导致在一个现象，我们描述为“气动援助”。我们正在开发的质量和热传递方程模型的矩阵组成，熔化和热解的程度，以及在任何时间和任何深度的气体在熔体中的量期间或之后的典型的3 ns脉冲从氮激光器在337 nm。气体扩散将导致气泡形成、生长、最终破裂和熔融基质的溅射，熔融基质夹带在结晶期间形成的分析物离子。这些方程依赖于基质及其脱羧产物的宏观性质，并将计算和预测以下的时间和空间模型：-基质对激光辐射的吸收，以及荧光对能量的一些损失。- 激光脉冲后加热、熔化、脱羧和随后冷却的效果。- 熔融基质和脱羧产物与CO2的过饱和。- 熔体中气泡的产生、生长和破裂，以及碎片作为液滴羽流的飞行。- 竞争损失的分析物离子的离子对和单离子的重组，无论是在身体的熔体和飞行微滴的羽流。- 基质及其脱羧产物从分析物离子中部分或全部蒸发。计算机模型的预测正在与实验MALDI数据进行比较。 （合作项目和其他技术研究与开发项目下报告了额外的工作量和仪器时间。）