title: Nonresonant, femtosecond laser vaporization and electrospray post-ionization mass spectrometry as a tool for biological tissue imaging.
abstract: An ambient mass spectrometry imaging (MSI) source is demonstrated with both high spatial and mass resolution that enables measurement of the compositional heterogeneity within a biological tissue sample. The source is based on nonresonant, femtosecond laser electrospray mass spectrometry (LEMS) coupled to a quadrupole time-of-flight (QTOF) mass analyzer. No matrix deposition and minimal sample preparation is necessary for the source. The laser, translation stage, and mass spectrometer are synchronized and controlled using a customized user interface. Single or multiple laser shots may be applied to each pixel. A scanning rate of 2.0s per pixel is achieved. Measurement of a patterned ink film indicates the potential of LEMS for ambient imaging with a lateral resolution of ∼60μm. Metabolites including sugar, anthocyanins and other small metabolites were successfully mapped from plant samples without oversampling using a spot size of 60×70μm(2). Molecular identification of the detected analytes from the tissue was enabled by accurate mass measurement in conjunction with tandem mass spectrometry. Statistical analysis, non-negative matrix factorization and principle component analysis, were applied to the imaging data to extract regions with distinct and/or correlated spectral profiles.
authors.affiliation: Department of Chemistry and Center for Advanced Photonics Research, Temple University, 1901 N. 13th St., Philadelphia, PA 19122, United States.
authors.forename: Fengjian
authors.initials: F
authors.lastname: Shi
authors.affiliation: Department of Chemistry and Center for Advanced Photonics Research, Temple University, 1901 N. 13th St., Philadelphia, PA 19122, United States.
authors.forename: Jieutonne J
authors.initials: JJ
authors.lastname: Archer
authors.affiliation: Department of Chemistry and Center for Advanced Photonics Research, Temple University, 1901 N. 13th St., Philadelphia, PA 19122, United States. Electronic address: rjlevis@temple.edu.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Levis
mesh_terms: D007834:Lasers; D057054:Molecular Imaging / Q000379:methods*; D025341:Principal Component Analysis; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D053719:Tandem Mass Spectrometry / Q000379:methods*
keywords: Ambient mass spectrometry; Femtosecond vaporization; Mass spectrometry imaging; Statistical analysis; Tissue imaging