MALDI Imaging Mass Spectrometry
Identification of new proteins from complex biological samples has become more democratic, conventional proteomics techniques do not provide information on the location of a protein of interest, or to follow the changing profile of expression of all peptides / proteins in tissues.
Direct analysis of tissues by mass spectrometry on instruments equipped with a MALDI ion source provides one-step image acquisition molecular distribution of molecules of interest within the tissue.
MALDI imaging mass spectrometry, introduced by the team of Richard Caprioli (Vanderbilt University, Nashville, USA) is now thriving and is well suited for finding biomarkers.
PROTIM is equipped with an area of MALDI imaging mass spectrometry.
The principle of this technology lies in a deposition on a MALDI plate of frozen tissue sections with a thickness of 10 to 20 micrometer. Matrix deposition is then performed on cryosections by spraying matrix at atmospheric pressure. The sample is finally introduced into the high vacuum analysis chamber of the mass spectrometer.
A UV laser beam will irradiate the sample, thus defining an area ablated, called "spot". For each "spot", a mass spectrum is generated. The experiment is repeated at regular intervals on the tissue section.
Once the entire analysis area irradiated, reprocessing software allows you to select specific m/z of the various mass spectra and to reconstruct maps of ion density, also called images, of the selected signals.
Each spot corresponds to one pixel of the image and the distance between each spot correspond to the spatial resolution.
A significant advantage of IMS is the capability to distinguish molecular species (proteins, peptides, lipids, sugars, metabolites) not easily achievable by other means, with a spatial resolution of about 50 micrometer.
Main equipments :
- Cryostat 3050S (Leica)
- ImagePrep (Bruker Daltonics)
- M5 sprayer (HTX Imaging)
- MALDI TOF TOF UltrafleXtreme (Bruker Daltonics)
- FTICR SolariX 7T Paracell combisource ESI/MALDI (Bruker Daltonics)
- Nanomate LESA-enabled (Advion)
- Vidéomicroscope BX51 (Olympus)
Example of studies realized by Protim :
Lagarrigue et al., Anal Chem 2014; 86: 5775-83.
Lagarrigue et al., J Proteome Res 2012;11(11):5453-5463.
Lagarrigue et al., Mol Cell Proteomics 2011;10(3):M110.005991.