Laser Desorption/Ionization on Au@TiO₂ Core@Shell Nanostars for Mass Spectrometric Analysis of Small Molecules

The core@shell nanostars composed of star-like Au nanocores with TiO₂ shells (Au@TiO₂ NSs) are synthesized in a one-pot reaction without any reducing or surface-controlling agents. The Au@TiO₂ NSs exhibit strong absorption in the UV region based on the interaction between the Au nanocore and the TiO₂ shell, and this optochemical property leads to the efficient laser desorption/ionization time-of-flight mass spectrometry (LDI-TOF-MS) analysis of small molecules with low background interference and high reproducible mass signals compared with spherical Au nanoparticles (NPs). The limit of detection and dynamic range values of various analytes also improved with Au@TiO₂ NSs compared with those obtained with spherical Au NPs. Our findings successfully demonstrate that Au@TiO₂ NSs are a promising matrix for the LDI-TOF-MS analysis of various small molecules as well as synthetic polymers.