In-source photocatalytic fragmentations of oligosaccharides in surface-assisted laser desorption/ionization mass spectrometry over titania nanoparticles

Abstract

In this study, we investigated the fragmentation behavior of oligosaccharides, specifically α-cyclodextrin (α-CD) and maltohexaose, using TiO₂ nanoparticles as ionizing substrates in SALDI-MS. Both compounds exhibited selective fragmentation at glycosidic bonds, with characteristic fragment ions for α-CD observed at m/z = 835, 673, 511, and 349. Similar fragmentation patterns were obtained with other metal oxide semiconductors (ZnO, Fe₂O₃, WO₃), while non-oxide semiconductors (CdS, CdSe) showed no fragmentation or molecular ion signals. The suppression of fragmentation upon glucose addition suggests the involvement of photoinduced holes, indicating that charge separation and oxide properties of the substrate contribute to the reaction. These findings demonstrate that SALDI-MS using oxide semiconductors enables controlled fragmentation of oligosaccharides and offers potential for structural analysis of glycans and photocatalytic surface reaction studies.