Matrix-assisted laser desorption tissue samples

Schwartz S, Reyzer M, Caprioli R. Direct tissue analysis using matrix-assisted laser desorption/ionization mass spectrometry practical aspects of sample preparation. /. Mass. Spectrom. 2003 38 699-708. 

Mass spectrometers are used not only to detect the masses of proteins and peptides, but also to identify the proteins, to compare patterns of proteins and peptides, and to scan tissue sections for specific masses. MS is able to do this by giving the mass-to-charge ratio of an ionized species as well as its relative abundance. For biological sample analysis, mass spectrometers are connected to an ionizing source, which is usually matrix-assisted laser desorption ionization (MALDI) [14], surface-enhanced laser desorption/ioni-zation (SELDI, a modified form of MALDI) [15], or electrospray ionization [16]. These interfaces enable the transfer of the peptides or proteins from the solid or liquid phase, respectively, to the gas (vacuum) phase inside the mass spectrometer. Both MALDI and electrospray ionization can be connected to different types of mass analyzers, such as quadrupole, quadruple-ion-traps, time of flight (TOF), or hybrid instruments such as quadrupole-TOF or Fourier transform-ion cyclotron resonance. Each of these instruments can... 

Recently, matrix-assisted laser desorption ionization-mass spectrometry (MALDI-MS) has been exploited to determine the complete profile of peptide messengers contained in a small sample of nervous tissues and even single neurons. This method is fast, sensitive, and provides highly specific and semiquantitative data of the peptides contained in complex mixtures of biological molecules. Other mass spectrometric methods, such as fast atom bombardment and electrospray mass spectrometry, are less sensitive and are also less suitable for the analysis of crude biological samples. 

Ruh, H., Sandhoff, R., Meyer, B., Gretz, N., and Hopf, C. 2013. Quantitative characterization of tissue globotetraosylceramides in a rat model of polycystic kidney disease by primadrop sample preparation and indirect high-performance thin layer chromatography-matrix-assisted laser desorption/ionization-time-of flight-mass spectrometry with automated data acquisition. Anal. Chem., 85 6233-6240. 

Traditional mass spectrometric imaging (MSI) methods, such as matrix-assisted laser desorption ionization (MALDI) and secondary ion mass spectrometry (SIMS), have become important tools for the investigation of molecular distributions in tissues due to their high ionization efficiencies and excellent lateral and depth resolutions. Invasive sample preparation and the need for vacuum conditions, however, are incompatible with the analysis of live samples. 

Key words Mass spectrometry imaging, matrix-assisted laser desorption/ionization, nervous tissue, pituitary, mouse, stretched sample, image reconstruction, automated data acquisition. 

Melchior K, Tholey A, Heisel S, Keller A, Lenhof HP, Meese E, et al. Protein versus peptide fractionation in the first dimension of two-dimensional high-performance liquid chromatography—matrix-assisted laser desorption/ionization tandem mass spectrometry for qualitative proteome analysis of tissue samples. J Chromatogr A 2010 1217(40) 6159-68. 

Trimpin, S. Herath, T. N. Inutan, E. D. Cemat, S. A. Wager-Miller, J. Mackie, K. Walker, J. M. Field-free transmission geometry atmospheric pressure matrix-assisted laser desorption/ionization for rapid analysis of unadulterated tissue samples. Rapid Commun. Mass Spectrom. 2009, 23, 3023-3027. 

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