title: Solid ionic matrixes for direct tissue analysis and MALDI imaging.
abstract: Direct analysis of tissue by MALDI-MS allows the acquisition of its biomolecular profile while maintaining the integrity of the tissue, giving cellular localization, and avoiding tedious extraction and purification steps. However, direct tissue analysis generally leads to some extent to a lowered spectral quality due to variation in thickness, freezing tissue date, and nature of the tissue. We present here new technical developments for the direct tissue analysis of peptides with ionic liquid made of matrix mixtures (alpha-cyano-4-hydroxycinnamic acid (CHCA)/2-amino-4-methyl-5-nitropyridine and alpha-cyano-4-hydroxycinnamic acid/N,N-dimethylaniline (CHCA/DANI)). The properties of these direct tissue analysis matrixes, especially CHCA/aniline when compared to CHCA, 2,5-dihydroxybenzoic acid, and sinapinic acid, are as follows: (1) better spectral quality in terms of resolution, sensitivity, intensity, noise, number of compounds detected, and contaminant tolerance, (2) better crystallization on tissues, i.e., coverage capacity, homogeneity of crystallization, homogeneity of crystal sizes, and time of crystallization, (3) better analysis duration in term of vacuum stability, (4) better resistance to laser irradiation especially for high-frequency lasers, (5) better ionic yield in negative mode, and (6) enough fragmentation yield to use the PSD mode on sections to get structural information. Applied to MALDI imaging on a MALDI LIFT-TOF with a 50-Hz laser frequency, these ionic matrixes have allowed the realization of a new type of image in both polarities and reflector mode using the same tissue section. These results give a new outlook on peptide tissue profiling by MS, characterization of compounds from tissue slices, and MALDI-MS high-quality imaging.
authors.affiliation: Laboratoire de Neuroimmunologie des Annélides, Equipe imagerie MALDI, UMR-CNRS 8017, Bâtiment SN3, Université des Sciences et Technologies de Lille, Villeneuve d'Ascq, France.
authors.forename: R
authors.initials: R
authors.lastname: Lemaire
authors.forename: J C
authors.initials: JC
authors.lastname: Tabet
authors.forename: P
authors.initials: P
authors.lastname: Ducoroy
authors.forename: J B
authors.initials: JB
authors.lastname: Hendra
authors.forename: M
authors.initials: M
authors.lastname: Salzet
authors.forename: I
authors.initials: I
authors.lastname: Fournier
mesh_terms: D000818:Animals; D001555:Benzene Derivatives / Q000737:chemistry*; D001923:Brain Chemistry; D052578:Ionic Liquids / Q000737:chemistry; D008297:Male; D008567:Membranes, Artificial; D051381:Rats; D017208:Rats, Wistar; D012680:Sensitivity and Specificity; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000295:instrumentation / Q000379:methods*; D013499:Surface Properties
chemical_list: D001555:Benzene Derivatives; D052578:Ionic Liquids; D008567:Membranes, Artificial