Engineered Reactive Interfaces Enable Mass Spectrometry Imaging of Multiple Thiols for Decoding PFOS-Induced Redox Dysregulation

Spatial profiling of multiple thiols shows great significance in elucidating the redox status across tissue microregions and understanding the molecular mechanisms of oxidative stress injury. Traditional matrix-assisted laser desorption/ ionization mass spectrometry imaging (MALDI MSI) relies on chemical derivatization for thiol visualization, but multistep derivatization protocols and nonspecific matrix-adduct formation compromise both detection sensitivity and spatial mapping fidelity. Herein, we engineer a reactive interface-assisted chemical derivatization platform for sensitive assessment of multiple thiols in various tissues via forming the “matrix-tissue-interface” sandwich structure. Reactive interface that predeposited with N-(9-Acridinyl) maleimide (NAM) probes enables profile multiple thiols including cysteamine (MEA), cysteine (Cys), cysteinyl-glycine (Cys–Gly), glutathione (GSH), and ergothioneine (ET) across various tissues. The increased sensitivity is likely due to the accelerated reaction efficiency that arises from the locally high NAM concentrations in the tissue–NAM interface, coupled with the sandwich architecture that mitigates ion suppression of NAM probes and prevents matrix–NAM interaction. The results demonstrated distinct tissue-specific distribution patterns of various thiols as well as redox dysregulation of kidney induced by PFOS exposure. This innovative MSI methodology offers a robust route to enhance the derivatization performance for low-abundance molecule imaging, facilitating the investigation of oxidative stress-related disease mechanisms and the toxicological effects of pollutant.