Surface-Assisted Laser Desorption/Ionization Imaging Mass Spectrometry (SALDI-IMS)-Based Detection of Vinca Alkaloids Distribution in the Petal of Madagascar Periwinkle

The surface-assisted laser desorption/ionization (SALDI) technique uses inorganic materials to aid desorption and ionization of molecules. SALDI is suitable for analyzing small molecules due to the absence of interfering signals in the low m/z range originating from the organic matrix. Imaging mass spectrometry (IMS) is a versatile imaging approach with high spatial resolution for analyzing various molecular species, but its application depends heavily on the ionization method. We have developed a functionalized titanium dioxide (TiO₂) nanowire as a solid substrate for SALDI-MS detection of low-molecular-weight molecules. We apply this novel substrate for imprinting fragile specimens such as petals and further SALDI-IMS analysis. The TiO₂ nanowire substrate is prepared from a commercial Ti plate by a hydrothermal process and subsequently chemically modified to improve the quality and selectivity of imprinting as well as the sensitivity of SALDI-IMS analysis. Here, the functionalized TiO₂ nanowire substrate is applied to visualize the distribution of vinca alkaloids in the petal of Madagascar periwinkle (Catharanthus roseus).