Self-assembled gold nanoparticle film for nanostructure-initiator mass spectrometry with passive on-line salt fractionation

We present the self-assembly of fluorinated-Au nanoparticle films as a mass-producible fabrication methodology for generating nanostructure-initiator mass spectrometry substrates. The nanostructured surfaces enable the direct high sensitivity detection of peptides (20 fmol) and other small molecules using laser desorption ionization. Further, through a photolithographic liftoff technique we can realize micropatterned fluorinated-Au nanoparticle films. These micropatterns create a discrete wettability patterns, allowing us to passively fractionate hydrophobic molecules of interest from high-salt background environments for robust and predictable MS.