NEDC matrix application for metabolite imaging using MALDI-MSI v1

Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) has emerged as a analytical technique more than 30 years ago. Originally developed as a method to analyze large biomolecules like proteins or peptides, MALDI-MS has over the years found a new application in the field of biological tissue imaging (MALDI-MSI). MALDI-MS has been utilized as an imaging tool for biological tissues, giving insight into the spatial distribution of molecules within complex tissue samples. Metabolomics research, which focuses on the study of metabolites present in a biological system, can benefit from this technology. Small molecules such as metabolites or lipids can be analyzed under the aspect of spatial distribution across tissue sections. This enables the investigation of metabolic pathways, biomarkers or the correlation of metabolic changes with specific tissue regions, uncovering potential links between metabolite variations and physiological or pathological conditions. Despite its potential, untargeted metabolomics using MALDI-MSI still faces several limitations. One major challenge is the diversity of matrices and protocols which are used to enhance ionization efficiency and the lack of information on metabolome coverage within different types of methods. One matrix of interest is NEDC (N-(1-napthyl)ethylendiamine dihydrochloride), which has gained recognition for its efficiency to visualize a broad range of metabolites. This protocol provides a guide on how to prepare fresh frozen tissue samples for MALDI-MSI of metabolites using the NEDC matrix. It covers cryosectioning and preparation of tissue samples and provides a method for NEDC matrix application using the Sunchrom Sprayer.