CHCA-modified Au nanoparticles for laser desorption ionization mass spectrometric analysis of peptides.

Gold nanoparticles (AuNPs) have been studied as a potential solid-state matrix for laser desorption/ionization mass spectrometry (LDI-MS) but the efficiency in ionization remains low. In this report, AuNPs are capped by a self-assembled monolayer of cysteamine and modified with alpha-cyano-4-hydroxycinnamic acid (CHCA) for effective MALDI measurements. CHCA-terminated AuNPs offer marked improvement on peptide ionization compared with citrate-capped or cysteamine-capped AuNPs.