Fe3O4-assisted laser desorption ionization mass spectrometry for typical metabolite analysis and localization: Influencing factors, mechanisms, and environmental applications

摘要： Fe3O4 has been suggested as an efficient matrix for small-molecule analysis by laser desorption ionization mass spectrometry (LDI-MS), but thus far there has been no systematic study exploring the influencing factors of nano-Fe3O4 on the detection of typical metabolites, or the mechanism by which nano-Fe3O4 assists the desorption and ionization of analytes after receiving laser energy. In this study, Fe3O4 nanoparticles with different physicochemical properties were synthesized and characterized. The results revealed that smaller particle size and greater surface hydroxyl amount of nano-spherical Fe3O4 could improve the intensity and relative standard deviation of typical metabolites by LDI-MS. The thermally driven desorption process played a vital role in LDI performance, but the chemical interactions between nano-Fe3O4 and analytes did not. Good intra- or inter-spot repeatability and linearity of analytes were obtained by the optimum Fe3O4-assisted LDI-MS. Finally, the developed method was successfully used for the rapid analysis and localization of endogenous metabolites in biofluids and whole zebrafish tissue section samples. Our results not only elucidate the influencing factors and mechanisms of nano-Fe3O4 for the detection of typical metabolites in LDI-MS but also reveal an innovative tool for the imaging of chemicals in the regions of interest in terms of eco-toxicological research.