Abstract Matrix application is a critical step in matrix-assisted laser desorption/ionisation mass spectrometry imaging (MALDI-MSI) analysis. Here, we describe a low cost, small size, and portable ultrasonic spraying device for various matrix deposition that is ideal for applying to obtain micron-sized (about 1–15 μm) cocrystallisation. The ultrasonic spray method was systematically compared with mainstream matrix application approaches based on optimization experiments. In the approach, ethanol was used as the solvent, and the spray direction was perpendicular to the MALDI sample slide. Seven different matrices were compared and we found that 2-[(2E)-3-(4-tert-butylphenyl)-2-methylprop-2-enylidene] malononitrile (DCTB) is a more suitable matrix for the detection of triacylglycerol (TAGs) and phosphatidylcholines (PCs) than other matrices. The DCTB matrix solution with concentrations of 5 mg mL−1 was applied on the surfaces of corn sections through ultrasonic spraying. The corn sections were then analysed through MALDI-MS in positive ion mode. MALDI-MSI allowed the simultaneous detection of multiple lipids including 16 TAGs and PCs in corn. The results demonstrated that the ultrasonic spraying device enables the deposition of MALDI matrix solution and provides the advantages of homogeneous micron-sized matrix crystallisation and satisfactory reproducibility.

中文翻译：

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使用柔性超声喷雾装置作为基质沉积方法对玉米中的脂质进行 MALDI-MS 成像

摘要 基质应用是基质辅助激光解吸/电离质谱成像 (MALDI-MSI) 分析的关键步骤。在这里，我们描述了一种用于各种基质沉积的低成本、小尺寸和便携式超声波喷涂装置，非常适合用于获得微米级（约 1-15 μm）共结晶。在优化实验的基础上，将超声喷涂方法与主流基质应用方法进行了系统比较。在该方法中，使用乙醇作为溶剂，喷雾方向垂直于 MALDI 样品载玻片。比较了七种不同的基质，我们发现 2-[(2E)-3-(4-叔丁基苯基)-2-methylprop-2-enylidene] 丙二腈 (DCTB) 是一种更适合检测三酰甘油 (TAGs) 的基质) 和磷脂酰胆碱 (PC) 而不是其他基质。将浓度为 5 mg mL-1 的 DCTB 基质溶液通过超声喷雾施用于玉米切片表面。然后在正离子模式下通过 MALDI-MS 分析玉米切片。MALDI-MSI 允许同时检测玉米中的多种脂质，包括 16 种 TAG 和 PC。结果表明，超声波喷涂装置能够沉积 MALDI 基质溶液，并提供均匀微米级基质结晶和令人满意的再现性的优点。