Nanoscale Single-Cell Mass Spectrometry Imaging via Tapered Fiber Projection Laser Desorption/Ionization Mass Spectrometry

Subcellular chemical mapping of endogenous biomolecules without labeling remains a pivotal challenge in life sciences, constrained by the limited lateral resolution and detection sensitivity of existing techniques. Herein, we report the development of tapered fiber projection laser desorption/ionization mass spectrometry (TFPLDI-MS), a new platform enabling nanoscale single-cell mass spectrometry imaging (SC-MSI). By integrating tapered fiber laser delivery with a telescopic projection system, this method achieves 570 nm lateral resolution, 400 nm imaging resolution, and a 6 amol detection limit, even at a 100 mm working distance. Exploiting enhanced ion yields from plasmonic nanoparticles, we demonstrate simultaneous nanoscale mapping of diverse exogenous drugs and endogenous phospholipids within individual cells with 400 nm pixel sizes, outperforming available laser-based SC-MSI techniques in imaging resolution, detectable analyte numbers at nanoscale sampling amounts, and operational flexibility of fiber-based sampling systems. Through spatially resolved lipidomics of HeLa cells at subcellular resolution, our TFPLDI-MSI system reveals drug-specific lipid alterations during apoptosis induced by 5-fluorouracil, paclitaxel, and cisplatin, elucidating heterogeneous therapeutic responses at the single-cell level. Crucially, the TFP system's contamination-free operation, indefinite operational lifespan, and modular design establish the TFPLDI-MS as a transformative tool for next-generation SC-MSI techniques, bridging the gaps between nanoscale chemical imaging and biomedical applications.