J Am Soc Mass Spectrom. 2020 Feb 5;31(2):292-297. doi: 10.1021/jasms.9b00066. Epub 2019 Dec 30.
Mass spectrometry imaging as a field has pushed its frontiers to three dimensions. Most three-dimensional mass spectrometry imaging (3D MSI) approaches require serial sectioning that results in a loss of biological information between analyzed slices and difficulty in reconstruction of 3D images. In this contribution, infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI) was demonstrated to be applicable for 3D MSI that does not require sectioning because IR laser ablates material on a micrometer scale. A commercially available over-the-counter pharmaceutical was used as a model to demonstrate the feasibility of IR-MALDESI for 3D MSI. Depth resolution (i.e., z-resolution) as a function of laser energy levels and density of ablated material was investigated. The best achievable depth resolution from a pill was 2.3 μm at 0.3 mJ/pulse. 2D and 3D MSI were performed on the tablet to show the distribution of pill-specific molecules. A 3D MSI analysis on a region of interest of 15 × 15 voxels across 50 layers was performed. Our results demonstrate that IR-MALDESI is feasible with 3D MSI on a pill, and future work will be focused on analyses of biological tissues.
质谱成像技术已将其前沿推进到三维领域。大多数三维质谱成像（3D MSI）方法需要进行切片，这会导致分析切片之间的生物信息丢失，并且难以重建 3D 图像。在本研究中，我们证明了红外基质辅助激光解吸电喷雾电离（IR-MALDESI）可用于 3D MSI，而无需切片，因为红外激光可在微米尺度上烧蚀材料。我们使用一种市售的非处方药物作为模型，证明了 IR-MALDESI 用于 3D MSI 的可行性。我们研究了激光能量水平和烧蚀材料密度对深度分辨率（即 z 分辨率）的影响。从药丸中获得的最佳深度分辨率为 0.3 mJ/脉冲时为 2.3 μm。我们对片剂进行了 2D 和 3D MSI 以显示药丸特定分子的分布。对 50 层的 15×15 体素感兴趣区域进行了 3D MSI 分析。我们的结果表明，IR-MALDESI 可用于药丸的 3D MSI，未来的工作将集中在生物组织的分析上。
