High resolution MALDI mass spectrometry imaging with laser-induced postionization

激光诱导定位高分辨率 MALDI 质谱成像

• 批准号: 290343045
• 负责人: Professor Dr. Klaus Dreisewerd
• 金额: --
• 依托单位: Forschungsabteilung Biomedizinische Massenspektrometrie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2016
• 资助国家: 德国
• 起止时间: 2015-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/290343045?language=en
• 关键词: resolution; MALDI; mass; spectrometry; imaging

MALDI mass spectrometry imaging (MALDI-MSI) enables simultaneous label-free recording of numerous biomolecules such as lipids, peptides, and metabolites directly from matrix-coated tissue slices. However, limited ion yields and ion suppression effects often restrict the applicability of the method, not least in high resolution applications where only little material is available per irradiated pixel. We recently introduced an extension of conventional MALDI, called MALDI-2. By using a second laser and a fine-vacuum ion source, MALDI-like secondary ionization processes could be initiated and the MSI signal intensities of - so far - lipids, glycoconjugates and liposoluble vitamins increased by up to two orders of magnitude [Soltwisch et al., Science 348 (2015) 211]. The research project aims at the development of this innovative technology and at obtaining a deeper knowledge about the processes underlying MALDI-2. Therefore, it can be broken down into two closely linked sections:Within the first main part >Methodisch-instrumentelle Entwicklungen und Anwendungen< we seek to further increase the analytical sensitivity for different classes of analytes, among others by using a Nd:YAG laser of high beam intensity, the development of improved MALDI-2 matrix systems, and by use of direct resonant 2-photon ionization for the analysis of metabolites. In this context, we will also explore whether metabolites could be postionized efficiently that are desorbed from tissue by means of direct IR-laser desorption. In a further section of the work program we seek to improve the lateral resolution to values of 1-2 µm by coupling MALDI-2 with the so-called transmission mode geometry. In collaboration with leading colleagues, the optimized technique will also be applied to a few selected biomedical research questions, among others for an improved visualization of glycolipids, serving as receptors for pathogenic microorganisms and their toxins.Within the fundamental investigations of the second main part >Mechanismen der MALDI-2< the processes of material ablation and ionization will be studied. We will characterize which physico-chemical properties of a MALDI-Matrix arre equired to enable an effective postionization, invrstigate which analyte classes are in principle amenable to MALD-2 and to direct 2-photon ionization, and optimize postionization irradiation conditions in both cases. By conducting extended wavelength studies, fine features of the ionization processes will be revealed and by characterizing the expansion dynamics of the material plume at varying experimental conditions, such as different focal diameters of the desorption laser beam, pressure of the buffer gas in the ion source, and the type oft excitation (top illumination vs. transmission mode geometry / UV- vs. IR-laser desorption), further important insight into the MALDI-2 mechanisms will be obtained.

MALDI 质谱成像 (MALDI-MSI) 能够直接从基质包被的组织切片中同步无标记记录众多生物分子，例如脂质、肽和代谢物。然而，有限的离子产率和离子抑制效应常常限制该方法的适用性，尤其是在每个照射像素仅有很少材料可用的高分辨率应用中。我们最近推出了传统 MALDI 的扩展，称为 MALDI-2。通过使用第二激光和高真空离子源，可以启动类似 MALDI 的二次电离过程，并且迄今为止，脂质、复合糖和脂溶性维生素的 MSI 信号强度增加了两个数量级 [Soltwisch 等人，Science 348 (2015) 211]。该研究项目旨在开发这项创新技术并获得有关 MALDI-2 底层流程的更深入的了解。因此，它可以分为两个紧密相连的部分：在第一个主要部分>Methodisch-instrumentelle Entwicklungen und Anwendungen<中，我们寻求进一步提高不同类别分析物的分析灵敏度，其中包括使用高光束强度的Nd:YAG激光器、开发改进的MALDI-2矩阵系统以及使用直接共振2光子电离来分析 代谢物。在这种情况下，我们还将探索是否可以通过直接红外激光解吸的方式有效地对从组织中解吸的代谢物进行定位。在工作计划的另一部分中，我们寻求通过将 MALDI-2 与所谓的传输模式几何结构耦合来将横向分辨率提高到 1-2 µm。与领先的同事合作，优化的技术还将应用于一些选定的生物医学研究问题，其中包括改善糖脂的可视化，作为病原微生物及其毒素的受体。在第二个主要部分>MALDI-2的机制<的基础研究中，将研究材料消融和电离的过程。我们将表征 MALDI 基质所需的物理化学性质，以实现有效的位置化，研究哪些分析物类别原则上适合 MALD-2 和直接 2 光子电离，并在这两种情况下优化位置化照射条件。通过进行扩展波长研究，将揭示电离过程的精细特征，并通过表征不同实验条件下材料羽流的膨胀动力学，例如解吸激光束的不同焦点直径、离子源中缓冲气体的压力以及激发类型（顶部照明与传输模式几何形状/紫外激光与红外激光解吸），进一步深入了解电离过程 将获得MALDI-2机制。