The nematode samples were also subjected to matrix application by sublimation deposition method, with 600 mg of DHB sublimated at 170 °C for the deposition thickness to reach 1.5 μm, using iMLayer (Shimadzu, Japan).
Prior to matrix application, in situ tissue digestion was performed with trypsin solution prepared (from lyophilised trypsin), at 20 µg/ml, by addition of 50 mM ammonium bicarbonate (NH4HCO3) pH 8, containing 0.5%% octyl-a/b-glucoside (OcGlc, w/v).
Where applicable, controlled conditions for matrix application for the MALDI imaging MS datasets were used to guarantee equal amounts of matrix and a homogenous matrix layer, a prerequisite for reproducible spectra quality.
Strict optimization of matrix application technique seems to be more critical when working with DHB.
Fig. 3 The MALDI-MSI workflow employed here for the analysis of excised tissue (a) post-MRI consisted of freeze thaw mounting of cryosectioned tissue (b), on tissue digestion for peptide analysis (omitted for lipids) prior to matrix application, and finally generation of MALDI-MSI (c) to enable the mapping and co-registration of peaks of interest found in the corresponding MALDI spectrum (d).
The homogeneity and the crystal sizes were controlled after matrix application by microscopy before fixing the sample on the sample holder of the imaging source.
The matrix application technique is critical to the success of a matrix-assisted laser desorption/ionization (MALDI) experiment.
Following enzyme application, slides were incubated at 37 °C for 2 h in a humidified chamber and dried in a desiccator prior to matrix application.
The device was used to characterize MALDI matrix application methods and evaluate their effects on chemical lateral displacement.
In a proof-of-concept experiment, the platform was also used to evaluate MALDI matrix application methods, specifically aerosol spray and sublimation methods.
T. C. Berkelbach, T. E. Markland and D. R. Reichman, Reduced density matrix hybrid approach: Application to electronic energy transfer.
