title: Selective improvement of peptides imaging on tissue by supercritical fluid wash of lipids for matrix-assisted laser desorption/ionization mass spectrometry.
abstract: There is a high analytical demand for improving the detection sensitivity for various peptides in matrix-assisted laser desorption/ionization imaging mass spectrometry (MALDI-IMS) because exhaustive distribution analyses of various peptides could help to reveal the function of peptides in vivo. To improve the sensitivity of peptide detection, we used supercritical fluid of CO2(scCO2) as washing solvent for a pretreatment to remove lipids. We evaluated whether our wash method using scCO2with an entrainer improved the detection of peptides and suppressed lipid detection in MALDI-IMS. Our analysis revealed that the signal intensities of peptides such as m/z 3339.8, 3530.9, 4233.3, 4936.7, and 4963.7 were increased in scCO2-washed samples. The greatest improvement in the signal-to-noise ratio (S/N) was found at m/z 4963.7, which was identified as thymosin β4, with the S/N reaching almost 190-fold higher than the control. Additionally, all of the improved signals were associated with the morphologic structure. Our method allows us to analyze the distribution of molecules, especially in the region of m/z 3000-5200. For these improvements, the polarity difference between scCO2and the matrix solution used was considered as a key. A wider variety of molecules can be analyzed in the future due to this improvement of the detection sensitivity by optimizing the polarity of scCO2with various entrainers. Graphical Abstract Mass spectra of m/z 4900-5000 obtained from a scCO2-washed tissue (upper, blue) and a control tissue (lower, red). Ion distribution of the signals at m/z 4936.7 and m/z 4963.7 specifically ditected from scCO2-washed samples.
authors.affiliation: Department of Cellular and Molecular Anatomy, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, Shizuoka, 431-3192, Japan.|International Mass Imaging Center, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, Shizuoka, 431-3192, Japan.|Research Fellow of Japan Society for the Promotion of Science, Kojimachi Business Center Building, 5-3-1 Kojimachi, Chiyoda-ku, Tokyo, 102-0083, Japan.
authors.forename: Shoko
authors.initials: S
authors.lastname: Matsushita
authors.affiliation: Department of Cellular and Molecular Anatomy, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, Shizuoka, 431-3192, Japan.|International Mass Imaging Center, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, Shizuoka, 431-3192, Japan.
authors.forename: Noritaka
authors.initials: N
authors.lastname: Masaki
authors.affiliation: Department of Applied Chemistry and Biochemical Engineering, Faculty of Engineering, Shizuoka University, 3-5-1 Johoku, Naka-ku, Hamamatsu, Shizuoka, 432-8561, Japan.
authors.forename: Kohei
authors.initials: K
authors.lastname: Sato
authors.affiliation: Health Innovation and Technology Center, Faculty of Health Sciences, Hokkaido University, Kita 12, Nishi 5, Kita-ku, Sapporo, Hokkaido, 060-0812, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Hayasaka
authors.affiliation: Department of Cellular and Molecular Anatomy, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, Shizuoka, 431-3192, Japan.|International Mass Imaging Center, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, Shizuoka, 431-3192, Japan.
authors.forename: Eiji
authors.initials: E
authors.lastname: Sugiyama
authors.affiliation: Health Innovation and Technology Center, Faculty of Health Sciences, Hokkaido University, Kita 12, Nishi 5, Kita-ku, Sapporo, Hokkaido, 060-0812, Japan.
authors.forename: Shu-Ping
authors.initials: SP
authors.lastname: Hui
authors.affiliation: Health Innovation and Technology Center, Faculty of Health Sciences, Hokkaido University, Kita 12, Nishi 5, Kita-ku, Sapporo, Hokkaido, 060-0812, Japan.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Chiba
authors.affiliation: Department of Applied Chemistry and Biochemical Engineering, Faculty of Engineering, Shizuoka University, 3-5-1 Johoku, Naka-ku, Hamamatsu, Shizuoka, 432-8561, Japan.
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Mase
authors.affiliation: Department of Cellular and Molecular Anatomy, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, Shizuoka, 431-3192, Japan. setou@hama-med.ac.jp.|International Mass Imaging Center, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, Shizuoka, 431-3192, Japan. setou@hama-med.ac.jp.|Preeminent Medical Photonics Education and Research Center, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, Shizuoka, 431-3192, Japan. setou@hama-med.ac.jp.|Department of Anatomy, The University of Hong Kong, 6/F, William MW Mong Block 21 Sassoon Road, Pokfulam, Hong Kong, SAR, China. setou@hama-med.ac.jp.|Riken Center for Molecular Imaging Science, 6-7-3 Minatojima-minamimachi, Chuo-ku, Kobe, Hyogo, 650-0047, Japan. setou@hama-med.ac.jp.|Division of Neural Systematics, National Institute for Physiological Sciences, 38 Nishigonaka Myodaiji, Okazaki, Aichi, 444-8585, Japan. setou@hama-med.ac.jp.
authors.forename: Mitsutoshi
authors.initials: M
authors.lastname: Setou
mesh_terms: D000818:Animals; D001923:Brain Chemistry; D002245:Carbon Dioxide / Q000737:chemistry; D025924:Chromatography, Supercritical Fluid / Q000379:methods; D005260:Female; D008055:Lipids / Q000302:isolation & purification*; D008810:Mice, Inbred C57BL; D010455:Peptides / Q000032:analysis*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D013947:Thymosin / Q000032:analysis; D000099201:Thymosin beta(4)
chemical_list: D002245:Carbon Dioxide; D008055:Lipids; D010455:Peptides; D013947:Thymosin; D000099201:Thymosin beta(4)
keywords: Imaging mass spectrometry; Matrix-assisted laser desorption/ionization; Peptides; Pretreatment; Supercritical fluid of CO2