Chemoselective Probes for Profiling of Carboxylic Acid Metabolites in Biological Tissue

Comprehensive profiling of carboxyl metabolites (CMs) is critical for biomarker discovery in disease pathogenesis but remains challenging due to matrix interference and poor ionization in mass spectrometry (MS). To overcome these limitations, we developed APH (amino-terminated polyuria–magnetic hexamethylenediamine composite), an integrated chemoselective probe for superior separation and detection. APH combines a magnetic Fe₃O₄@SiO₂ core for rapid isolation, a functionalized polyurea shell with high-density binding sites, a chemoselective moiety for covalent CMs capture, and a cleavable linker incorporating an MS signal-enhancing tag. This design enables specific enrichment of CMs directly from complex biosamples and efficient matrix removal via magnetic separation and gentle analyte release. Applied to mouse cecum samples, APH demonstrated deep carboxyl sub-metabolome profiling capabilities. By effectively reducing matrix suppression and enhancing sensitivity, APH facilitates the annotation of low-abundance CM biomarkers previously obscured in conventional analyses. This platform advances separation science for targeted metabolomics in biomarker research.