Li Yue, Shrestha Bindesh, Vertes Akos
Department of Chemistry, Institute for Proteomics Technology and Applications, George Washington University, Washington, DC 20052, USA.
Anal Chem. 2007 Jan 15;79(2):523-32. doi: 10.1021/ac061577n.
An atmospheric pressure (AP) MALDI imaging interface was developed for an orthogonal acceleration time-of-flight mass spectrometer and utilized to analyze peptides, carbohydrates, and other small biomolecules using infrared laser excitation. In molecular imaging experiments, the spatial distribution of mock peptide patterns was recovered with a detection limit of approximately 1 fmol/pixel from a variety of MALDI matrixes. With the use of oversampling for the image acquisition, a spatial resolution of 40 microm, 5 times smaller than the laser spot size, was achieved. This approach, however, required that the analyte was largely removed at the point of analysis before the next point was interrogated. Native water in plant tissue was demonstrated to be an efficient natural matrix for AP infrared laser desorption ionization. In soft fruit tissues from bananas, grapes, and strawberries, potassiated ions of the most abundant metabolites, small carbohydrates, and their clusters produced the strongest peaks in the spectra. Molecular imaging of a strawberry skin sample revealed the distribution of the sucrose, glucose/fructose, and citric acid species around the embedded seeds. Infrared AP MALDI mass spectrometric imaging without the addition of an artificial matrix enables the in vivo investigation of small biomolecules and biological processes (e.g., metabolomics) in their natural environment.
为正交加速飞行时间质谱仪开发了一种大气压（AP）基质辅助激光解吸电离成像接口，并利用红外激光激发来分析肽、碳水化合物和其他小生物分子。在分子成像实验中，从各种基质辅助激光解吸电离基质中恢复了模拟肽模式的空间分布，检测限约为1飞摩尔/像素。通过在图像采集时使用过采样，实现了40微米的空间分辨率，比激光光斑尺寸小5倍。然而，这种方法要求在下一个点被询问之前，分析物在分析点处基本被去除。植物组织中的天然水被证明是用于AP红外激光解吸电离的有效天然基质。在香蕉、葡萄和草莓的软果组织中，最丰富的代谢物、小碳水化合物及其簇的钾离子在光谱中产生最强的峰。草莓皮样品的分子成像揭示了蔗糖、葡萄糖/果糖和柠檬酸物种在嵌入种子周围的分布。无需添加人工基质的红外AP基质辅助激光解吸电离质谱成像能够在自然环境中对小生物分子和生物过程（如代谢组学）进行体内研究。
