Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, USA.
Anal Chem. 2012 Apr 3;84(7):3240-5. doi: 10.1021/ac3006704. Epub 2012 Mar 22.
An infrared laser was used to ablate material from tissue sections under ambient conditions for direct collection on a matrix assisted laser desorption ionization (MALDI) target. A 10 μm thick tissue sample was placed on a microscope slide and was mounted tissue-side down between 70 and 450 μm from a second microscope slide. The two slides were mounted on a translation stage, and the tissue was scanned in two dimensions under a focused mid-infrared (IR) laser beam to transfer material to the target slide via ablation. After the material was transferred to the target slide, it was analyzed using MALDI imaging using a tandem time-of-flight mass spectrometer. Images were obtained from peptide standards for initial optimization of the system and from mouse brain tissue sections using deposition either onto a matrix precoated target or with matrix addition after sample transfer and compared with those from standard MALDI mass spectrometry imaging. The spatial resolution of the transferred material is approximately 400 μm. Laser ablation sample transfer provides several new capabilities not possible with conventional MALDI imaging including (1) ambient sampling for MALDI imaging, (2) area to spot concentration of ablated material, (3) collection of material for multiple imaging analyses, and (4) direct collection onto nanostructure assisted laser desorption ionization (NALDI) targets without blotting or ultrathin sections.
采用红外激光在环境条件下从组织切片中烧蚀材料，直接收集到基质辅助激光解吸电离（MALDI）靶上。将 10μm 厚的组织样本放在显微镜载玻片上，然后将其组织面向下安装在距离另一张显微镜载玻片 70 至 450μm 的位置。将两张载玻片安装在平移台上，通过聚焦中红外（IR）激光束在两个维度上扫描组织，以通过烧蚀将材料转移到靶载玻片上。将材料转移到靶载玻片上后，使用串联飞行时间质谱仪进行 MALDI 成像分析。使用肽标准品获得图像，以对系统进行初步优化，并使用沉积在预先涂有基质的靶标上或在样品转移后添加基质的方式对小鼠脑组织切片进行分析，并与标准 MALDI 质谱成像进行比较。转移材料的空间分辨率约为 400μm。激光烧蚀样品转移提供了一些传统 MALDI 成像不可能实现的新功能，包括（1）MALDI 成像的环境采样，（2）烧蚀材料的区域到点浓度集中，（3）进行多次成像分析的材料收集，以及（4）直接收集到纳米结构辅助激光解吸电离（NALDI）靶上，无需印迹或超薄切片。
