Introducing specificity and sensitivity in imaging mass spectrometry

成像质谱学(IMS)提供有关样品中分子定位的信息。它已经成为通过直接分析薄组织切片来描绘和表征生物分子空间分布的一种强有力的方法。对于数百种不同的内源性化合物，包括蛋白质、肽、脂类和代谢物，可以同时获得与组织结构直接相关的分子特异性图谱。 在这项研究提案中，我们将利用我们在IMS方面的专业知识来解决生物成像领域尚未满足的重要需求。因此，这项建议将侧重于开发分析方法，以提高IMS分析类固醇、胆固醇酯和神经酰胺等新型内源性分子的特异性和敏感性。必须开发浓缩方法，以便于确定可用于疾病诊断或预后或作为治疗反应指标的脂类靶标。研究的两个主轴将被探索。 1)替代解吸/电离剂的开发。我们已经证明，在组织切片的表面添加金属银可以特定地成像胆固醇、脂肪酸和其他烯烃。其他金属、金属氧化物和阳离子对各种类型的脂类和代谢物具有有趣的亲和力，可以有效地探索这些亲和力，以实现对IMS的高度敏感性和特异性。还将在对指纹进行法医分析的背景下对这些发展的结果进行调查，以确定区分性别的分子标记、滥用物质和爆炸物等非法化合物以及暴露于与指纹模式高度相关的放射性材料后的分子标记： 2)开发化学定制的亲和表面，以从薄组织切片中特定地捕获目标脂类和代谢物，同时保持其空间完整性。组织切片将首先被放置在这些亲和表面上。分析物捕获后，切片将被移除，保留的分子将用IMS进行分析。 通过他的研究计划，IMS方法开发的持续努力将使我们能够对生物样本中的脂质和代谢物进行更深入和独特的分析，以补充我实验室已经开发的那些分析。总体而言，这些新方法将有助于广泛的生物学应用，包括人类疾病和障碍，以及了解细胞、器官和整个生物体的正常发育和功能。

Imaging Mass Spectrometry (IMS) provides information on the localization of molecules in a sample. It has become a powerful way to profile and characterize the spatial distribution of biomolecules through the direct analysis of thin tissue sections. Molecular-specific maps directly correlated with tissue architecture may be simultaneously obtained for several hundreds of different endogenous compounds including proteins, peptides, lipids and metabolites. In this research proposal, we will leverage our expertise in IMS to address important unmet needs in the field of biological imaging. Accordingly, this proposal will focus on the development of analytical methods to improve the specificity and sensitivity of IMS for the analysis of novel classes of endogenous molecules including steroids, cholesterol esters and ceramides. Enrichment methods must be developed to facilitate the identification of lipid targets that can be used in the diagnosis or prognosis of disease or as indicators of therapeutic response. Two main axis of research will be explored. 1) The development of alternative desorption/ionization agents. We already have demonstrated that the addition of metallic silver on the surface of tissue sections allows to specifically image cholesterol, fatty acids, as well as other olefins. Other metals, metal oxides and cations have interesting affinities for various classes of lipids and metabolites that can be usefully explored to implement high degrees of sensitivity and specificity to IMS. The sum of findings from these developments will also be investigated in the context of the forensic analysis of fingermarks to identify molecular markers which differentiate gender, illicit compounds such as substances of abuse and explosives and molecular markers after exposure to radioactive material with a high degree of correlation with fingerprint patterns: 2) The development of chemically tailored affinity surfaces to specifically capture targeted lipids and metabolites from thin tissue sections while maintaining their spatial integrity. Tissue sections will first be deposed on these affinity surfaces. After analyte capture, the sections will be removed and the retained molecules analyzed by IMS. Through his research program, continued efforts in IMS method development will allow a deeper and unique analysis of lipids and metabolites from biological samples complementary to those already developed in my laboratory. Overall, these new methods will be useful for a wide range of biological applications including human diseases and disorders as well as understanding normal development and functioning of cells, organs and whole organisms.