Mass Spectrometry Imaging of Bio‐oligomer Polydispersity in Plant Tissues by Laser Desorption Ionization from Silicon Nanopost Arrays

Abstract

Mass spectrometry imaging (MSI) enables simultaneous spatial mapping for diverse molecules in biological tissues.M atrix-assisted laser desorption ionization (MALDI) mass spectrometry (MS) has been am ainstream MSI method for aw ide range of biomolecules.H owever,M ALDI-MSI of biological homopolymers used for energy storage and molecular feedstocki sl imited by,e .g.,p referential ionization for certain molecular classes.Matrix-free nanophotonic ionization from silicon nanopost arrays (NAPAs) is an emerging laser desorption ionization (LDI) platform with ultra-trace sensitivity and molecular imaging capabilities.H ere,w es how complementary analysis and MSI of polyhydroxybutyric acid (PHB), polyglutamic acid (PGA), and polysaccharide oligomers in soybean root nodule sections by NAPA-LDI and MALDI. ForP HB,n umber and weight average molar mass, polydispersity,and oligomer sizedistributions across the tissue section and in regions of interest were characterized by NAPA-LDI-MSI.