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What is MALDI Imaging Mass Spectrometry?

Matrix-assisted laser desorption/ionization (MALDI) imaging mass spectrometry is a widely used soft ionization technique used to measure particularly fragile samples such as biomolecules. Compared to other mass spectrometry ionization methods, MALDI imaging mass spectrometry results in much less fragmentation of the molecular species. 

MALDI imaging mass spectrometry works by immobilizing the analyte of interest in an inert matrix. The MALDI imaging matrix should not induce any changes in the sample of interest, and simply act as a medium to absorb the laser irradiation used and subsequently ionize the analyte of interest. There are numerous methods to prepare samples in matrices, including spraying or sublimation. 

The key improvement of MALDI imaging mass spectrometry, when compared to simple MALDI methods, is that as well as having the mass spectrum recorded for the analyte, the position in the sample is also measured. The sample is laser irradiated, ionized and a new spectrum recorded for each position, meaning that a full two-dimensional image can be built up of the sample with each data point containing the full mass spectrum recorded, thus giving the technique its spatial resolution. 

MALDI imaging mass spectrometry has become a popular technique as, unlike many microscopy methods, it is a label-free way to study biological samples. MALDI imaging can achieve very high spatial resolutions and recent developments in the technique are making it possible to create three dimensional images to provide volume information on the sample in a similar way to magnetic resonance imaging (MRI). 

Applications 

Another advantage of MALDI imaging mass spectrometry is its suitability for various sample types. Tissue samples can be directly prepared on microscope slides for imaging, and the reduced fragmentation from the soft ionization process makes it ideal for detecting complex profiles of small molecules to profile drug distributions in biological samples. The spatial element of the information recovered in MALDI imaging makes it possible to identify which regions of the tissue certain drugs may be concentrated in and build an understanding of drug transport and uptake in the body. 

JEOL’s MALDI Imaging Solutions 

JEOL’s MALDI imaging instruments offer excellent mass-resolution, one of the key parameters for the unambiguous identification of molecular species and discrimination between compounds in complex mixtures.1 The JMS-S3000 SpiralTOF Plus is an all-in-one MALDI imaging system that can be paired with JEOL’s SCiLS Lab MVS to both capture and analyze all your data. The volume of data generated by MALDI imaging datasets can be challenging to handle, but SCiLS Lab MVS comes with many built-in options for visualization and processing to streamline this process. 

The JMS-S3000 MALDI imaging instrument can manage the complexity of even spectrally congested brain tissue samples with large numbers of lipids. Combining high mass resolution with high spatial resolution makes it possible to identify even minor lipid families in the sample. This is aided using electric sectors in the analyzer to improve chemical noise, particularly in low m/z regions, by removing any post-source ions. 

Are you looking for a robust technique to provide a wealth of information on complex biological samples? Contact JEOL today to discover how their MALDI imaging solutions could support your workflows.



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