Desorption Electrospray Ionization Mass Spectrometry Imaging: Principles, Advancements, and Multidisciplinary Applications.

Desorption electrospray ionization-mass spectrometry imaging (DESI-MSI), as an ambient ionization technique, enables label-free, matrix-free, and minimal sample pretreatment molecular mapping of biological surfaces under atmospheric pressure. Since its inception in 2004, DESI-MSI has evolved through innovations in ionization sources, sprayer design, and data processing, allowing high-throughput visualization of spatial distributions for diverse molecules (e.g., lipids, metabolites, drugs) in tissues. This review systematically reviews the fundamental principles, instrumental configurations, and critical technical parameters of DESI-MSI. Recent technological advancements, specifically the development of nanoscale DESI achieving spatial resolutions under 50 μm and the implementation of additive-enhanced solvents such as metal ions and reactive anions to enhance sensitivity and specificity, are critically evaluated. Furthermore, the multidisciplinary applications of DESI-MSI are comprehensively examined: (1) in biomedicine, it facilitates cancer margin delineation (e.g., breast, prostate tumors) and neuropathological biomarker discovery; (2) in pharmaceutical research, it enables in situ drug distribution analysis and tissue metabolism profiling; (3) in plant sciences, it supports spatial mapping of phytochemicals, pesticide residues, and host-microbe interactions. Nevertheless, despite its advantages in real-time analysis and nondestructive sampling, inherent challenges persist, including limited spatial resolution (~200 μm) and complexities in interpreting complex datasets. Future work should emphasize the integration of multimodal imaging approaches, machine learning-driven data processing pipelines, and clinical translation strategies for intraoperative diagnostics. Collectively, this study positions DESI-MSI as a transformative spatial metabolomics tool with expanding potential in clinical diagnostics and high-throughput drug screening.