Institute of Interdisciplinary Integrative Medicine Research, Shanghai University of Traditional Chinese Medicine, 1200 Cailun Road, Shanghai 201203, P. R. China.
State Key Laboratory of Organometallic Chemistry and National Center for Organic Mass Spectrometry in Shanghai, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, P. R. China.
Anal Chem. 2022 Mar 8;94(9):3756-3761. doi: 10.1021/acs.analchem.1c04926. Epub 2022 Feb 22.
Mass spectrometry imaging has become a hot research field owing to its ability to reflect the distribution of multiple metabolites in tissue. However, not all kinds of metabolites have great ionization efficiency in mass spectrometry imaging. The mass signals of low polar metabolites like monoglycerides and diglycerides may be seriously suppressed. Many strategies have been proposed to fix the problem, such as on-tissue derivatization and online derivatization. Also, some challenges were encountered when implementing these approaches. Herein, a platform coupled online quaternized derivatization and laser ablation carbon fiber ionization mass spectrometry imaging has been developed. The mass signals of monoglycerides and diglycerides were drastically increased in the platform, and high-quality mass images of these metabolites could be acquired readily. In the platform, metabolites were first desorbed by a laser and then reacted online with a derivatization reagent transmitted by carbon fiber ionization, which also undertook the postionization of derivatization products. Pyridine acted as the main derivatization reagent to target metabolites with hydroxyl groups. Remarkably, the derivatization reaction proceeded rapidly without any catalyst owing to the high energy provided by the laser. The mass images of eight monoglycerides and 21 diglycerides were achieved after applying the platform into human ovarian cancer tissues. Notably, a higher mass intensity of these glycerides was captured in cancerous tissues than in para-cancerous tissues, which might infer aberrations in glyceride metabolisms of cancerous tissues.
质谱成像因其能够反映组织中多种代谢物的分布而成为热门研究领域。然而，并非所有类型的代谢物在质谱成像中都具有很高的离子化效率。单甘油脂和二甘油脂等低极性代谢物的质谱信号可能会受到严重抑制。已经提出了许多策略来解决这个问题，例如组织内衍生化和在线衍生化。在实施这些方法时也遇到了一些挑战。在此，开发了一种在线季铵化衍生化和激光烧蚀碳纤维离子化质谱成像联用平台。在该平台中，单甘油脂和二甘油脂的质谱信号大大增强，可以轻松获得这些代谢物的高质量质谱图像。在该平台中，代谢物首先被激光解吸，然后在线与碳纤维离子化传输的衍生化试剂反应，该试剂还承担了衍生化产物的后离子化。吡啶作为主要的衍生化试剂，靶向具有羟基的代谢物。值得注意的是，由于激光提供的高能量，衍生化反应无需任何催化剂即可快速进行。将该平台应用于人卵巢癌组织后，获得了 8 种单甘油脂和 21 种二甘油脂的质谱图像。值得注意的是，在癌组织中捕获到的这些甘油酯的质量强度高于癌旁组织，这可能暗示癌组织中甘油酯代谢存在异常。
