Thin film surfaces suitable to multimodal ionization for TOF-SIMS and LDI mass spectrometry of biomolecules

We report that the flat surfaces of thin films (50-nm-thick Si and Au) prepared on thermal insulator (SiO2) substrates provide versatile sample plates exhibiting multimodality for TOF-SIMS and LDI MS (laser desorption ionization mass spectrometry). Previously, the crystalline Si thin film was reported to be applicable to matrix-free LDI of biomolecules using SOI (silicon-on-insulator) wafers. One of the benefits from the previous LDI method is that various surface materials can be employed while still maintaining LDI performance, including materials that are also amenable to TOF-SIMS ionization. In this work, we demonstrate that SOI wafers (50-nm-thick Si on SiO2) and Au thin films (50-nm-thick Au on glass wafer) display sensitive ionization of peptide and drug molecules both in TOF-SIMS and LDI MS, offering an important platform for multimodal ionization that will open a new opportunity combining unique advantages of each mass spectrometry for bimolecular detection. Copyright (c) 2014 John Wiley & Sons, Ltd.