RESEARCH PROFILES: In vivo molecular imaging by LAESI MS

摘要

To perform MS analyses on living organisms, researchers have developed atmospheric-pressure ionization techniques such as desorption electrospray ionization (DESI) and electrospray-assisted laser desorption/ionization (ELDI) that don't require the addition of a matrix. Several groups quickly extended this concept to a whole range of organisms and to additional applications, such as imaging. In their recent AC paper (2008, 80, 4575-4582), Akos Vertes and his colleagues at George Washington University performed in vivo molecular imaging and depth profiling on the leaves of plants with their own matrixless technique, laser ablation ESI (LAESI). LAESI combines atmospheric pressure (AP) IR/MALDI with electrospray postionization. First, a 2.94 (mu)m laser ablates the water-rich sample in a resonant manner. Next, the ejected neutral species are intercepted by an electrospray plume and form multiply charged ions, which are sent into the TOF mass analyzer. The technique is quantitative over 4 orders of magnitude, does not require an internal standard, and has femtomole detection limits for small molecules.