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. 2009 Jan;20(1):89-95.
doi: 10.1016/j.jasms.2008.09.008. Epub 2008 Sep 12.

Improved MALDI-TOF imaging yields increased protein signals at high molecular mass

Barbara D Leinweber  1 , George Tsaprailis, Terrence J Monks, Serrine S Lau
Affiliations

Improved MALDI-TOF imaging yields increased protein signals at high molecular mass

Barbara D Leinweber et al. J Am Soc Mass Spectrom. 2009 Jan.

Abstract

Matrix assisted laser desorption ionization (MALDI) mass spectrum images are created from an array of mass spectra collected over a tissue surface. We have increased the mass range of proteins that can be detected in tissue sections from kidneys, heart, lung and brain of different rodent species by a modification of the sandwich technique, which involves co-crystallizing matrix with analyte. A tissue section is placed upon a drop of sinapinic acid matrix dissolved in 90% ethanol and 0.5% Triton X-100. Once the matrix has dried, a seed layer of sinapinic crystals is added as a dispersion in xylene. Additional layers of sinapinic acid are added as solutions in 90% ethanol followed by 50% acetonitrile. Numerous peaks with signal to noise ratio of four or greater are observed between 25 kDa to 50 kDa. This represents approximately 10 times as many peaks as are detected using traditional matrix spotting and spraying.

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Figures

Figure 1
Figure 1
Traditional method and the modified sandwich method for tissue imaging. Snap frozen tissue is cut in 10-20 μm slices and mounted on a conductive MALDI plate. A. Sinapinic acid (SA) sprayed with a nebulizer or spotted either by hand or with a robot 10. B. In the modified sandwich method a 14 μm slice of frozen tissue is processed as illustrated and described in detail in the text.
Figure 2
Figure 2
Key points in the development of the enhanced method. A. High m/z signals are not obtained with spray coating 14 μm mouse kidney slices. The top spectrum is the average from the entire kidney section. A spectrum from analyte that leached from the kidney with the matrix is also shown. B. Mouse kidney sections (14 μm) placed upon a drop of SA/EtOH yield a better signal. C. Triton X-100 (SA/EtOH/T) in the bottom layer further improves the signal from mouse kidney sections. D. Replacement of SA/ACN with SA/EtOH as the 2nd top layer.
Figure 3
Figure 3. Comparison of high m/z signal intensity in rat heart, lung and brain
Figure 4
Figure 4
Regional spectra from the rat kidney. A. An H&E stained slice adjacent to the one used for mass spectral imaging (ISOM, inner stripe of the outer medulla; OSOM, outer stripe of the outer medulla). B. The H&E stained image (black) aligned with the total ion current (TIC), with overlap shown in green. C-E. Composite spectra of the regions in panel A. Arrows mark peaks chosen for imaging in Figures 5 and 6.
Figure 5
Figure 5
MALDI and MALDI overlay images of the proteins indicated by arrows in Figure 4C & 4D.
Figure 6
Figure 6
MALDI and MALDI overlay images of the proteins indicated by arrows in Figure 4E.
See this image and copyright information in PMC

References

    1. Leinweber BD, Monks TJ, Lau SS. The Ethanol Triton X-100 Sandwich Method Yields High Resolution and m/z MALDI Mass Spectral Images on Tissue. J Am Soc Mass Spectrom. 2006;17(5) 1:111S.
    1. Stoeckli M, Farmer TB, Caprioli RM. Automated mass spectrometry imaging with a matrix-assisted laser desorption ionization time-of-flight instrument. J Am Soc Mass Spectrom. 1999;10(1):67–71. - PubMed
    1. Caprioli RM, Farmer TB, Gile J. Molecular imaging of biological samples: localization of peptides and proteins using MALDI-TOF MS. Anal Chem. 1997;69(23):4751–60. - PubMed
    1. Chaurand P, Norris JL, Cornett DS, Mobley JA, Caprioli RM. New developments in profiling and imaging of proteins from tissue sections by MALDI mass spectrometry. J Proteome Res. 2006;5(11):2889–900. - PubMed
    1. Chaurand P, Schwartz SA, Reyzer ML, Caprioli RM. Imaging mass spectrometry: principles and potentials. Toxicol Pathol. 2005;33(1):92–101. - PubMed

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