title: Alternative two-step matrix application method for imaging mass spectrometry to avoid tissue shrinkage and improve ionization efficiency.
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.
authors: Division of Translational Research, Exploratory Oncology Research & Clinical Trial Center, National Cancer Center, 5-1-1 Tsukiji, Chuo-ku, Tokyo, 1040045, Japan; Division of Clinical Pharmacology Group for Translational Research Support Core, National Cancer Center Research Institute, 5-1-1 Tsukiji, Chuo-ku, Tokyo, 1040045, Japan.
authors: Shuichi
authors: S
authors: Shimma
authors: Yuki
authors: Y
authors: Takashima
authors: Jun
authors: J
authors: Hashimoto
authors: Kan
authors: K
authors: Yonemori
authors: Kenji
authors: K
authors: Tamura
authors: Akinobu
authors: A
authors: Hamada
mesh_terms: D000818:Animals; D016477:Artifacts; D045744:Cell Line, Tumor; D005260:Female; D006651:Histocytochemistry / Q000379:methods*; D006801:Humans; D008099:Liver / Q000737:chemistry; D013058:Mass Spectrometry / Q000379:methods*; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D009374:Neoplasms, Experimental / Q000737:chemistry; D009930:Organic Chemicals / Q000737:chemistry*; D010793:Phthalazines / Q000032:analysis / Q000737:chemistry; D010879:Piperazines / Q000032:analysis / Q000737:chemistry
chemical_list: D009930:Organic Chemicals; D010793:Phthalazines; D010879:Piperazines; C531550:olaparib
keywords: drug; imaging mass spectrometry; improvement ionization efficiency; matrix application; tissue shrinkage