6-Aminoquinoline/2,5-Dihydroxybenzoic Acid: A Novel Binary Matrix for Enhanced Detection of Monosaccharides and Oligosaccharides in Tissues by MALDI-MSI

Abstract

Matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) is a powerful tool for the in situ mapping and spatial characterization of endogenous saccharides in biological tissues. However, current MALDI-MSI methods cannot simultaneously discriminate and precisely visualize mono- and oligosaccharide isomers in native tissues, creating a key analytical bottleneck. To overcome this limitation, we developed a rationally optimized 6-aminoquinoline/2,5-dihydroxybenzoic acid (6-AQ/DHB) binary matrix for high-sensitivity, isomer-selective saccharide imaging. The 6-AQ/DHB matrix produces homogeneous nanoscale crystalline deposits, ensures exceptional vacuum stability, enables isomer discrimination, and provides a wide linear dynamic response. This matrix enables qualitative and quantitative saccharide analysis of serum samples from diabetic patients and healthy individuals. Furthermore, we realized in situ spatial discrimination and visualization of various saccharide isomers in tissue sections of Actinidia arguta, germinating Taxus chinensis var. mairei seed and rat brain. This advancement establishes a robust analytical platform for in situ saccharide imaging, offering good potential for studies in spatial glycomics, analytical chemistry, and plant metabolism.