Dr. Lingjun Li

University of Wisconsin, Madison

Friday, February 16, 2024
12:00 Noon
Room 120 – Meyerhoff Chemistry Building
Host: Dr. Kamal Seneviratne

“Revealing the Chemical Space of Biological Systems through the Lens of MassSpectrometry Imaging Coupled with In Situ Chemical Reactions”

Mass spectrometric imaging (MSI) provides an attractive opportunity to detect and probe the molecular content of tissues in an anatomical context. This technique creates distribution maps of select compounds without the need for priori knowledge of target analytes. In this presentation, I will describe our efforts and recent progress in mapping and imaging of a wide variety of signaling molecules in several biological systems, highlighting the unique challenges and important roles of MSI in the areas of proteomics/peptidomics, glycomics, and lipidomics. To further enhance the chemical information extracted from in situ MALDI MSI experiments, we report on a multiplex-MSI method, which combines high-resolution accurate mass (HRAM) MSI technology with data dependent acquisition (DDA) tandem MS analysis in a single experiment. In addition, the utility of a novel subatmospheric pressure (SubAP)/MALDI source coupled with a hybrid quadrupole-orbitrap mass spectrometer for in situ imaging of glycans from formalin-fixed paraffin-embedded (FFPE) tissue sections and its translation to clinical cancer tissue microarray analysis will be highlighted. Moreover, to further improve the sensitivity of MALDI MSI, a nanosecond photochemical reaction (nsPCR) strategy has been developed to enable enhanced neuropeptide and metabolite identification and visualization from complex tissue samples through on-demand removal of surrounding matrices within nanoseconds. Additionally, a novel approach employing peracetic acid (PAA) induced epoxidation coupled with MS for localization of double bonds in unsaturated fatty acids is developed, enabling both quantification and spatial visualization of fatty acid isomers in complex biological samples ranging from human cell lines to cancer tissue samples. Finally, I will present our recent progress in the application of trapped ion mobility coupled with MSI for single cell lipidome profiling and its utility to probe lipidome remodeling induced by pharmacological intervention and map brain region specific lipidomic changes in Alzheimer’s disease.