Abstract:  With the increased complexity of new and diverse modalities in the pharmaceutical industry, there is a high demand to develop more sensitive and versatile analytical tools. HRMS has become an important analytical technique due to its broad applications in small molecule structure identification, molecular imaging, large biomolecules such as protein and antibody-drug conjugate characterization. In this presentation, I will discuss several unique/innovative approaches we developed and applied to solve challenging problems in drug discovery and development.

• Label free molecular imaging applications in tissues and tablets

Fatty liver disease phenotype is characterized by both an increase in the concentration and synthesis rate of neutral lipids (NL) across the liver. The spatial distribution of multiple lipids classes is poorly characterized in fatty liver disease. A novel method was development to enhance ionization of neutral lipid via Sodium-Doped Gold-Assisted Laser Desorption Ionization. This method can allow investigators to obtain spatial resolution of lipogenic flux by coupling imaging mass spectrometry and isotope tracers. Long-acting injectable (LAI) implants can deliver a drug over several weeks to years, reducing the dosing frequency and improving patient adherence. An innovative approach of using MALDI-MSI to characterize the drug release process from LAI implants was developed. This method provides definitive molecular-level information about the chemical composition as well as the distribution of APIs simultaneously.

• Development of Electron-based dissociation (ExD) to differentiate isomeric amino acids

Isomeric amino acids such as aspartic isoaspartic acid leucine/isoleucine, and valine/norvaline are widely present in peptides and proteins. For example: Leu and Ile count for 16% of all amino acids in proteins. Nva differs from Leu by only one methyl group, and mis-incorporation of Nva is common during the production of recombinant proteins. Conventional CID generates the same m/z value for these isomers and consequently is unable to differentiate isobaric species. Therefore, it poses a challenge to establishing correct peptide and proteins sequences. Electron-activated dissociation (ExD) was developed to differentiate these isomeric amino acid residues in therapeutic peptide and protein.

Abstract:  Recent innovations in instrumentation in the Bruker MALDI imaging platform—the timsTOF fleX MALDI-2 with microGRID—are now enabling deeper biological investigations in small metabolites and large proteins. Specific examples of metabolic pathways and cancer biology with results as 5 µm spatial resolution are shown.