Surface interactions of a homologous series of α,ω-amino acids on colloidal silver and gold

Surface enhanced Raman spectroscopy (SERS) was used to characterize a homologous series of α,ω‐amino acids on colloidal gold and silver. Raman and SER spectra of the α,ω‐amino acids, NH2(CH2)nCOOH (n = 3–7), are presented and analyzed, revealing the probable conformations of the molecules on the metal surfaces. The α,ω‐amino acids interact with silver and gold through both the amine and carboxylate end groups, and modify the conformation of the molecular backbone in order to maximize these interactions. An odd–even effect is observed for backbone conformations of molecules adsorbed to the silver substrate. The anomolous SER spectrum of 5‐aminopentanoic acid on gold suggests the possibility of condensation polymerization at the gold surface. © 1999 John Wiley & Sons, Inc. Biospectroscopy 5: 9–17, 1999