Investigation of the inhibitory effects of TiO2 on the β-amyloid peptide aggregation

TiO2 thin films are of great interest as biocompatible coatings and also as photocatalytic self-cleaning and antimicrobial coatings. In this work we used beta-amyloid as a model for infectious protein to investigate the attachment and photocatalytic degradation. TiO2 films were prepared on stainless steel substrates using magnetron sputtering. The films were characterised before and after exposure to beta-amyloid (1-42), using XRD, Raman spectroscopy, XPS and AFM. The TiO2 film was mostly composed of the anatase phase with a relatively high surface roughness. The presence of Raman peaks at 1668 cm(-1) and 1263 cm(-1), with the XPS spectral feature for nitrogen at 400 eV, confirmed the adsorption of amyloid on surface. Following exposure of the beta-amyloid contaminated TiO2 to UV-B irradiation a slight shift of amide modes was observed. Furthermore, the amide I spectra show an overall decrease in alpha-helix content with presence of a minor peak around 1591 cm(-1), which is related to tryptophanyl and tyrosinyl radicals, which can lead to conformational change of beta-amyloid. The C1s band at 292.2 eV suggests the formation of free carboxylic acid. The loss in the crucial structure of beta-amyloid leads to reduce the fibril formation, thought to be induced through a photocatalytic process. (C) 2014 Elsevier B.V. All rights reserved.