Bottom-Up Mass Spectrometry Imaging of Tissue Proteins

About This Grant

Abstract Mass spectrometry imaging (MSI) enables spatially resolved identification of hundreds of molecules in a tissue sample, providing profound insights into biological and environmental processes across spatial dimensions. This multiplexing capability, combined with the label-free nature of the technique, has led to the widespread adoption of mass spectrometry as an emerging tool for molecular imaging. However, in terms of protein imaging of tissue samples by MSI, most of methods utilize “top-down” approach for protein analysis, which is challenging due to low sensitivity of MS instrument for intact protein ion detection (in comparison to peptide ion detection). As a result, the number of proteins identified in MSI experiments without digesting proteins into peptides is quite limited. To tackle this problem, in this project, we propose to develop a novel approach of “bottom-up” MSI for protein analysis directly from tissues using nano-DESI ionization in combination with online ultrafast microdroplet protein digestion technique. As our proposed “bottom-up” MSI technology focuses on peptide ion analysis instead of intact protein ion analysis, it would have higher sensitivity than “top-down” MSI approaches and enable identification of many more proteins based on their constituent peptide detection from one single MSI experiment. As proteins represent one of the most important functional molecules in tissue and cells, we expect that our proposed method would have very broad biomedical applications.