Stained glass sample preparation

Artifacts introduced through sample preparation are common materials these may be bits of facial tissue, wax, epithelial cells, hair, or dried stain, all inadvertently introduced by the microscopist. Detergent residues on so-called precleaned microscope slides and broken glass are common artifacts, as are knife marks and chatter marks from sectioning with a faulty blade, or scratch marks from grinding and polishing. 

Therefore, a major breakthrough toward clinical MALDI imaging was the discovery that the MALDI matrix can be washed off after an experiment and histologically stained images can then be obtained from the same section (1, 10, 11). For practical use, the sample has to be prepared on a slide that addresses the requirements for both imaging methods (1) optical transparency for transmission microscopy and (2) electrical conductivity for MALDI analysis. Conductive indium-tin-oxide (ITO)-coated glass slides fulfill both requirements and have become the de facto standard. 

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