Detection of Amyloid Marker Thioflavin T on Ag Nanoparticles by Surface-Enhanced Raman Scattering

Abstract

The vibrational characterization of the dye used for detection of amyloid aggregates Thioflavin T (ThT) was carried out by means of Raman and surface-enhanced Raman scattering (SERS). The Raman spectrum of ThT in aqueous solution correlates very well with the spectrum of ThT with the torsional angle between the benzothiazole (BT) and dimethylaminobenzene (DMB) moieties of 37¿ calculated using DFT calculations at the B3LYP/6-31+G** level. The SERS technique was very useful for the detection of two structures of ThT molecules in the vicinity of the metal nanoparticles: directly adsorbed onto the metal surface and molecules forming multilayers. The structure of ThT molecules in multilayers is similar to the structure of free ThT in aqueous solution. The molecules directly adsorbed on the metal surface actually correspond to the molecules with 90¿ torsional angle between the BT and DMB rings.