MALDI Imaging of Liquid Extraction Surface Analysis Sampled Tissue

Abstract

Combined mass spectrometry imaging methods in which two different techniques are executed on the same sample have recently been reported for a number of sample types. Such an approach can be used to examine the sampling effects of the first technique with a second, higher resolution method and also combines the advantages of each technique for a more complete analysis. In this work matrix-assisted laser desorption ionization mass spectrometry imaging (MALDI MSI) was used to study the effects of liquid extraction surface analysis (LESA) sampling on mouse brain tissue. Complementary multivariate analysis techniques including principal component analysis, non-negative matrix factorization, and t-distributed stochastic neighbor embedding were applied to MALDI MS images acquired from tissue which had been sampled by LESA to gain a better understanding of localized tissue washing in LESA sampling. It was found that MALDI MS images could be used to visualize regions sampled by LESA. The variability in sampling area, spatial precision, and delocalization of analytes in tissue induced by LESA were assessed using both single-ion images and images provided by multivariate analysis.

Mass spectrometry tools and workflows for revealing microbial chemistry

“…They continue to develop MS based approaches towards more accessible, portable and affordable MS technologies, aiming to analyze samples from their native natural environment with minimum intervention 104, 107–109 . Several ambient methods have developed for diverse applications including: Direct Analysis in Real Time (DART), Desorption Atmospheric Pressure Chemical Ionization (DAPCI), Electrospary-assiated Laser Disorption Ionization (ELDI), Laser-Ablation Electrospray Ionization (LAESI) and Liquid Extraction Surface Analysis (LESA) 110, 111 . DESI, nanospray DESI (nanoDESI) and liquid microinjection surface sampling probe (LMJ-SSP) are some of the atmospheric ionization methods that have been used for microbial analysis and are further discussed 95, 104, 111–114 .…”

A Critical and Concise Review of Mass Spectrometry Applied to Imaging in Drug Discovery

“…To date, none of these platforms are used in isolation for meaningful stand-alone R&D but are powerful bolt-on capabilities. For example, liquid extraction surface analysis (LESA) has been demonstrated to add extra sensitivity at the expense of spatial resolution [18][19][20] when applied to metabolic profiling, 21 drug imaging, 3 or challenging intact protein targets. 22,23 Combining similar surface droplet microjunction techniques with pre-ionization chromatography increases the specificity and range of detected targets, but compromises on overall throughput.…”

Sample Treatment for Tissue Proteomics in Cancer, Toxicology, and Forensics

“…A recent study performed by Randall et al (2016) presented a combination of MALDI and LESA for the investigation of lipids, drugs, and proteins all from a single tissue section [8]. This collaborative study used animal brain tissue but, the methodologies could potentially be translational to human tissue samples.…”