Single-Atom Pt-Anchored MoO x Matrix for On-Tissue Calibration in Quantitative Mass Spectrometry Imaging

Quantitative mass spectrometry imaging (qMSI) enables spatially resolved metabolite profiling in biological tissues, yet reliable concentration mapping remains constrained by high matrix-derived background interference, limited metabolite coverage, and insufficient calibration robustness. To overcome these challenges, a single-atom platinum-anchored molybdenum oxide matrix (denoted as Ptsa/MoOx) was developed for qMSI. Compared with conventional organic matrices, the Ptsa/MoOx matrix not only substantially enhances metabolite ion signals but also effectively suppresses low-mass background interference. Comprehensive structural characterization revealed oxygen-deficient MoOx with highly dispersed Pt single atoms, and mechanistic investigation indicated that charge-mediated desorption and ionization contribute to the enhanced matrix performance. Using Ptsa/MoOx-assisted qMSI, an on-tissue calibration strategy was established across a wide polarity range of metabolites, achieving excellent linear responses from 43 to 853 ng mm−2. For metabolites lacking authentic standards, a class-matched concentration-referencing strategy was applied to generate concentration-referenced spatial maps for 124 metabolites. Application to five paired pancreatic tumor and adjacent non-tumor specimens demonstrated region-dependent differences across multiple lipid-related pathways as a proof-of-concept tissue application. Collectively, these results establish Ptsa/MoOx-assisted qMSI as an on-tissue calibrated platform for spatial metabolomics and demonstrate its potential for characterizing metabolic heterogeneity in biological tissues.