Mesoporous carbon hollow spheres with open and large pores enable ultra-sensitive metabolic profiling

Metabolomics has attracted increasing interest in recent years because metabolites offer a unique and dynamic layer of biological insight beyond genomics and proteomics. Owing to their rapid turnover, analytical techniques that enable fast, highly sensitive detection with minimal sample input are in strong demand. Matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS) is a powerful molecular analysis tool with high sensitivity and specificity, requiring only 0.5-1 µL of sample. However, the use of organic matrices generates significant background interference in the low mass range, which limits its application in metabolite detection. To address this challenge, this study introduces the first-of-its-kind nano-bomb nanostructure-initiator mass spectrometry (NB-NIMS) for sensitive metabolite detection. Instead of organic matrices, NB-NIMS utilizes initiator-loaded rationally designed mesoporous carbon hollow spheres (MCHS) to enhance analyte desorption efficiency. MCHS feature large hollow cavities (~230 nm diameter) and radial trumpet-like pore structures (~11 nm), enabling efficient initiator loading. Upon laser irradiation, the initiator-loaded MCHS act as nano-bombs, triggering rapid and concentrated vaporization that markedly enhances analyte desorption and achieves attomolar-level detection sensitivity. Using this platform, metabolic fingerprints were constructed to differentiate macrophage phenotypes. This work represents a significant advancement in mass spectrometry for ultra-sensitive small-molecule detection in complex biofluids.