Session: Parallel session 3 - AI and Bioinformatics

A Plug-and-Play Laser Post-Ionization Module for AP-MALDI-2 Orbitrap Imaging with Improved Sensitivity

Gilles FRACHE¹, Maureen FEUCHEROLLES¹, Olivier BOUTON¹, Mathieu GÉRARD¹, Eugene MOSKOVETS²

¹Luxembourg Institute of Science and Technology (LIST), Belvaux, Luxembourg
²MassTech, Inc., Columbia, MD, United States

Introduction:

Atmospheric pressure MALDI (AP-MALDI) mass spectrometry is a powerful tool for the analysis of biological samples. AP-MALDI enables to preserve native hydrated tissues and to analyse volatile molecules. While AP-MALDI sources are commercially available, the potential of post-ionization at atmospheric pressure (AP-MALDI-2) remained uncertain until recently. During AP-MALDI-2 a second laser pulse occurs to ionize the molecules desorbed by the first laser. There is currently no commercially available AP-MALDI-2 source. Here, we present the design and validation of a compact and plug-and-play AP-MALDI-2 prototype.

Methods:

We developed a compact post-ionization module prototype (patent LU505964) coupled to the commercial AP/MALDI UHR ion source from MassTech Inc. (USA), renowned for its versatility in switching between MALDI and LC/MS-MS configurations in a matter of seconds. The prototype was coupled to a high resolution Orbitrap Exploris 480 MS.

Results:

Post ionization efficiency was evaluated on the EquiSPLASH ™ standard lipids solution (Avanti polar lipids, USA). Fold change increase was established for every lipid class of the mix. Overall, the AP/MALDI-2 prototype exhibited remarkable enhancements in lipids detection. Then the prototype was used to perform AP-MALDI-2 imaging, showing increased sensitivity of detection for lipids already detected without laser post-ionization. Furthermore, AP/MALDI-2 allowed for the detection of lipids which could not be detected without laser post-ionization. For instance, TG and PI were only detected in the section analysed with the post-ionization module. Finally, more identifications were observed with AP/MALDI-2 in the Metaspace.

Conclusion:

Our work pioneers a potentially marketable, compact AP/MALDI-2 prototype with post-ionization, significantly boosting sensitivity in lipid imaging applications.