Surface-Enhanced Raman Scattering Spectroscopy of Sialosides and Their Derivatives

The spectra of the surface-enhanced Raman scattering (SERS) of some glycosides of N-acetylneuraminic acid and their derivatives, including α-benzyl glycoside, β-benzyl glycoside, α-methyl glycoside, methyl ester of α-benzyl glycoside, α-benzyl glycoside of N-trifluoroacetylneuraminic acid, and α-benzyl glycoside of 4-epi-N-acetylneuraminic acid, were analyzed. The assignment of the bands appearing in the SERS spectra was made. It was shown that for adsorption on the SERS-active surface, carboxylic, N-acetyl, and hydroxyl groups of the glycerol residue of sialic acid are important. A correlation between the intensity of the SERS spectra of sialosides and their binding together with hemagglutinin of the influenza virus was found. It was proposed that the conformations of sialosides in the complex with hemagglutinin and upon the adsorption at the SERS-active surface are similar, which explains this correlation. Surface characteristics that determine a given type of the sialoside adsorption were considered.