Alternative two‐step matrix application method for imaging mass spectrometry to avoid tissue shrinkage and improve ionization efficiency |
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Authors: | Shuichi Shimma Yuki Takashima Jun Hashimoto Kan Yonemori Kenji Tamura Akinobu Hamada |
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Institution: | 1. Division of Translational Research, Exploratory Oncology Research & Clinical Trial Center, National Cancer Center, , Chuo‐ku, Tokyo, 1040045 Japan;2. Division of Clinical Pharmacology Group for Translational Research Support Core, National Cancer Center Research Institute, , Chuo‐ku, Tokyo, 1040045 Japan;3. Department of Medical Oncology and Translational Research, Graduate School of Medical Science, Kumamoto University, , Chuo‐ku, Kumamoto, 8608556 Japan;4. Department of Breast and Medical Oncology, National Cancer Center Hospital, , Chuo‐ku, Tokyo, 1040045 Japan |
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Abstract: | Mass spectrometry (MS) was used to measure the concentrations of drug and biological compounds in plasma and tissues. Matrix‐assisted laser desorption/ionization (MALDI) imaging MS (IMS) has recently been applied to the analysis of localized drugs on biological tissue surfaces. In MALDI‐IMS, matrix application process is crucial for successful results. However, it is difficult to obtain homogeneous matrix crystals on the tissue surface due to endogenous salts and tissue surface heterogeneity. Consequently, the non‐uniform crystals degrade the quality of the spectrum and likely cause surface imaging artifacts. Furthermore, the direct application of matrix solution can cause tissue shrinkage due to the organic solvents. Here, we report an alternative two‐step matrix application protocol which combines the vacuum deposition of matrix crystals and the spraying of matrix solution to produce a homogeneous matrix layer on the tissue surface. Our proposed technique can also prevent cracking or shrinking of the tissue samples and improve the ionization efficiency of the distributed exogenous material. Copyright © 2013 John Wiley & Sons, Ltd. |
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Keywords: | imaging mass spectrometry drug matrix application improvement ionization efficiency tissue shrinkage |
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