Department of Chemistry, m/c 111, University of Illinois at Chicago, Chicago, IL 60607-7061, USA.
J Mass Spectrom. 2010 Feb;45(2):137-45. doi: 10.1002/jms.1716.
Vacuum ultraviolet single photon ionization (VUV SPI) is a soft ionization technique that has the potential to address many of the limitations of matrix-assisted laser desorption/ionization (MALDI) for imaging MS. Laser desorption postionization (LDPI) uses VUV SPI for postionization and is experimentally analogous to a MALDI instrument with the addition of a pulsed VUV light source. This review discusses progress in LDPI-MS over the last decade, with an emphasis on imaging MS of bacterial biofilms, analytes whose high salt environment make them particularly resistant to imaging by MALDI-MS. This review first considers fundamental aspects of VUV SPI including ionization mechanisms, cross sections, quantum yields of ionization, dissociation and potential mass limits. The most common sources of pulsed VUV radiation are then described along with a newly constructed LDPI-MS instrument with imaging capabilities. Next, the detection and imaging of small molecules within intact biofilms is demonstrated by LDPI-MS using 7.87 eV (157.6 nm) VUV photons from a molecular fluorine excimer laser, followed by the use of aromatic tags for detection of selected species within the biofilm. The final section considers the future prospects for imaging intact biological samples by LDPI-MS.
真空紫外单光子电离（VUV SPI）是一种软电离技术，有可能解决基质辅助激光解吸/电离（MALDI）在成像 MS 方面的许多局限性。激光解吸后电离（LDPI）使用 VUV SPI 进行后电离，并且在实验上类似于 MALDI 仪器，除了增加了脉冲 VUV 光源。本综述讨论了过去十年中 LDPI-MS 的进展，重点是细菌生物膜的成像 MS，这些分析物的高盐环境使它们特别难以通过 MALDI-MS 进行成像。本综述首先考虑了 VUV SPI 的基本方面，包括电离机制、截面、离化量子产率、解离和潜在的质量极限。然后描述了最常见的脉冲 VUV 辐射源，以及具有成像能力的新型 LDPI-MS 仪器。接下来，使用来自分子氟准分子激光器的 7.87 eV（157.6nm）VUV 光子通过 LDPI-MS 演示了完整生物膜内小分子的检测和成像，然后使用芳香族标记物检测生物膜内的选定物种。最后一部分考虑了 LDPI-MS 对完整生物样品成像的未来前景。
