Synergistic Effect of the Heterostructure of Au Nanoislands on TiO 2 Nanowires for Efficient Ionization in Laser Desorption/Ionization Mass Spectrometry.

A combination nanostructured matrix with metal Au nanoislands and semiconductor TiO ₂ nanowires is presented to enhance both desorption and ionization efficiency in laser desorption/ionization (LDI) mass spectrometry. The heterostructure of Au nanoislands on TiO ₂ nanowires was fabricated via (1) TiO ₂ nanowire synthesis through a modified wet-corrosion method and (2) Au nanoisland formation through thermal annealing of a sputtered Au layer on the TiO ₂ nanowires. Herein, the synergistic effect of this heterostructure for highly efficient ion production was experimentally elucidated in terms of the formation of high temperature on the surface of Au and the creation of a Schottky barrier at the Au-TiO ₂ interface. Finally, four types of immunosuppressors were analyzed to demonstrate the improved ionization performance of the heterostructure for LDI mass spectrometry.