title: Imaging of Endogenous Metabolites of Plant Leaves by Mass Spectrometry Based on Laser Activated Electron Tunneling.
abstract: A new mass spectrometric imaging approach based on laser activated electron tunneling (LAET) was described and applied to analysis of endogenous metabolites of plant leaves. LAET is an electron-directed soft ionization technique. Compressed thin films of semiconductor nanoparticles of bismuth cobalt zinc oxide were placed on the sample plate for proof-of-principle demonstration because they can not only absorb ultraviolet laser but also have high electron mobility. Upon laser irradiation, electrons are excited from valence bands to conduction bands. With appropriate kinetic energies, photoexcited electrons can tunnel away from the barrier and eventually be captured by charge deficient atoms present in neutral molecules. Resultant unpaired electron subsequently initiates specific chemical bond cleavage and generates ions that can be detected in negative ion mode of the mass spectrometer. LAET avoids the co-crystallization process of routinely used organic matrix materials with analyzes in MALDI (matrix assisted-laser desorption ionization) analysis. Thus uneven distribution of crystals with different sizes and shapes as well as background peaks in the low mass range resulting from matrix molecules is eliminated. Advantages of LAET imaging technique include not only improved spatial resolution but also photoelectron capture dissociation which produces predictable fragment ions.
authors.affiliation: Mass Spectrometry Center for Structural Identification of Biological Molecules and Precision Medicine, Key Laboratory of Pesticides and Chemical Biology, Ministry of Education, College of Chemistry, Central China Normal University, Wuhan, Hubei 430079, P. R. China.
authors.forename: Lulu
authors.initials: L
authors.lastname: Huang
authors.affiliation: Mass Spectrometry Center for Structural Identification of Biological Molecules and Precision Medicine, Key Laboratory of Pesticides and Chemical Biology, Ministry of Education, College of Chemistry, Central China Normal University, Wuhan, Hubei 430079, P. R. China.
authors.forename: Xuemei
authors.initials: X
authors.lastname: Tang
authors.affiliation: Mass Spectrometry Center for Structural Identification of Biological Molecules and Precision Medicine, Key Laboratory of Pesticides and Chemical Biology, Ministry of Education, College of Chemistry, Central China Normal University, Wuhan, Hubei 430079, P. R. China.
authors.forename: Wenyang
authors.initials: W
authors.lastname: Zhang
authors.affiliation: Mass Spectrometry Center for Structural Identification of Biological Molecules and Precision Medicine, Key Laboratory of Pesticides and Chemical Biology, Ministry of Education, College of Chemistry, Central China Normal University, Wuhan, Hubei 430079, P. R. China.
authors.forename: Ruowei
authors.initials: R
authors.lastname: Jiang
authors.affiliation: Mass Spectrometry Center for Structural Identification of Biological Molecules and Precision Medicine, Key Laboratory of Pesticides and Chemical Biology, Ministry of Education, College of Chemistry, Central China Normal University, Wuhan, Hubei 430079, P. R. China.
authors.forename: Disong
authors.initials: D
authors.lastname: Chen
authors.affiliation: Mass Spectrometry Center for Structural Identification of Biological Molecules and Precision Medicine, Key Laboratory of Pesticides and Chemical Biology, Ministry of Education, College of Chemistry, Central China Normal University, Wuhan, Hubei 430079, P. R. China.
authors.forename: Juan
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Mass Spectrometry Center for Structural Identification of Biological Molecules and Precision Medicine, Key Laboratory of Pesticides and Chemical Biology, Ministry of Education, College of Chemistry, Central China Normal University, Wuhan, Hubei 430079, P. R. China.
authors.forename: Hongying
authors.initials: H
authors.lastname: Zhong
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism; D001729:Bismuth / Q000737:chemistry; D019343:Citric Acid / Q000378:metabolism; D003035:Cobalt / Q000737:chemistry; D003460:Crystallization; D003517:Cyclopentanes / Q000378:metabolism; D004583:Electrons; D005227:Fatty Acids / Q000378:metabolism; D005875:Gibberellins / Q000378:metabolism; D007834:Lasers; D055432:Metabolomics / Q000379:methods; D053768:Metal Nanoparticles / Q000737:chemistry; D010087:Oxides / Q000737:chemistry; D054883:Oxylipins / Q000378:metabolism; D018515:Plant Leaves / Q000378:metabolism*; D012666:Semiconductors; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D027844:Vitaceae / Q000378:metabolism; D015034:Zinc Oxide / Q000737:chemistry
chemical_list: D003517:Cyclopentanes; D005227:Fatty Acids; D005875:Gibberellins; D010087:Oxides; D054883:Oxylipins; D019343:Citric Acid; D003035:Cobalt; C011006:jasmonic acid; D000040:Abscisic Acid; C033301:bismuth oxide; C007842:gibberellic acid; D015034:Zinc Oxide; D001729:Bismuth; C060728:cobalt oxide