Surface‐enhanced Raman spectroscopy of biomolecules. Part I.—water‐soluble proteins, dipeptides and amino acids

Abstract

Abstract Surface‐enhanced Raman (SER) spectra of water‐soluble proteins (lysozyme and bovine serum albumin), dipeptides and amino acids were analysed. Chemisorption is a necessary condition for the appearance of SER spectra on silver electrodes and hydrosols for these compounds. The Raman cross‐section enhancement per molecule may reach a factor of 10 5 –10 6 , depending closely on the frequency of the vibration band considered. The mechanism of enhancement has a short‐range character and is attributed to the π‐electron complexes of the aromatic amino acids side‐chains and σ‐complexes of the molecular groups containing unshared electron pairs with the metal. The effect of induced optical activity in the visible region for aromatic amino adsorbed by silver hydrosols has been elucidated.