Mass spectrometry imaging of rat brain sections: nanomolar sensitivity with MALDI versus nanometer resolution by TOF–SIMS

in Analytical and Bioanalytical Chemistry (2010), 396(1), 151-162

Mass spectrometry imaging is becoming a more and more widely used method for chemical mapping of organic and inorganic compounds from various surfaces, especially tissue sections. Two main different ... [more ▼]

Mass spectrometry imaging is becoming a more and more widely used method for chemical mapping of organic and inorganic compounds from various surfaces, especially tissue sections. Two main different techniques are now available: matrix-assisted laser desorption/ionizaton, where the sample, preliminary coated by an organic matrix, is analyzed by a UV laser beam; and secondary ion mass spectrometry, for which the target is directly submitted to a focused ion beam. Both techniques revealed excellent performances for lipid mapping of tissue surfaces. This article will discuss similarities, differences, and specificities of ion images generated by these two techniques in terms of sample preparation, sensitivity, ultimate spatial resolution, and structural analysis. [less ▲]

In Situ Lipidomic Analysis of Nonalcoholic Fatty Liver by Cluster TOF-SIMS Imaging

in Analytical Chemistry (2009), 81(8), 2823-2831

Pores formation on cell membranes by hederacolchiside A1 leads to a rapid release of proteins for cytosolic subproteome analysis

in Journal of Proteome Research (2008), 7(4), 1683-1692

Hederacolchiside A1 was used to progressively permeabilize the membrane of human melanoma MEL-5 cells. Holes formation was followed by Scanning Electron Microscopy and interaction of the saponin with ... [more ▼]

Hederacolchiside A1 was used to progressively permeabilize the membrane of human melanoma MEL-5 cells. Holes formation was followed by Scanning Electron Microscopy and interaction of the saponin with cholesterol and phospholipids by TOF-SIMS. 2D-LC-MS/MS and 2D-SDS-PAGE show that the release of soluble proteins into serum-free culture media increases with time. This can lead to a new rapid and efficient strategy to analyze the cytosolic subproteome and it opens the door to get information from the cytosolic compartment for clinical proteomic studies. [less ▲]

Attempts for molecular depth profiling directly on a rat brain tissue section using fullerene and bismuth cluster ion beams

in International Journal of Mass Spectrometry (2007), 260(2-3), 115-120

Kinetics of solvent addition on electrosprayed ions in an electrospray source and in a quadrupole ion trap

in International Journal of Mass Spectrometry (2001), 210/211

Benzylpyridinium cations readily fragment in the electrospray source by loss of pyridine to give benzyl cations (M-79). The full-scan spectra obtained with some instruments also show, in addition, an m/z ... [more ▼]

Benzylpyridinium cations readily fragment in the electrospray source by loss of pyridine to give benzyl cations (M-79). The full-scan spectra obtained with some instruments also show, in addition, an m/z (M-38) peak corresponding to the addition of acetonitrile, being present in the solvent mixture, on the benzyl cations. Here we report that the addition reaction can occur in the source region of electrospray mass spectrometry instruments, and in a quadrupole ion trap. The kinetics of acetonitrile addition was monitored in an ion trap, acetonitrile being provided by leakage from the source, through the heated capillary. For benzyl ions with different substituents, the addition kinetics has been found positively correlated with the Brown parameter sigma+ of the benzyl radical, and therefore with the effective charge density on the alpha-carbon atom of the benzyl ion. This is consistent with the Langevin or average-dipole-orientation (ADO) theory of ion–molecule reaction kinetics. [less ▲]