title: Surface-enhanced Raman spectroscopy for detection of toxic amyloid β oligomers adsorbed on self-assembled monolayers.
abstract: Surface-enhanced Raman spectroscopy (SERS) was used to detect different spectral features of small (1-2 nm) and large (5-10 nm) synthetic amyloid Aβ-42 oligomers, exhibiting high and no detectable neurotoxicities, respectively. Adsorption of peptides at self-assembled monolayers (SAM) terminated by methyl and pyridinium groups was employed to differentiate toxic and non-toxic oligomers. Three SAMs were analyzed: hydrophobic heptanethiol (HT) and octadecanethiol (ODT) as well as positively charged N-(6-mercapto)hexylpyridinium (MHP) chloride. SERS study revealed twofold adsorption effect, changes in the monolayer structure and appearance of new bands associated with the adsorbed peptides. A band at 1387 cm(-1), observed as a result of the SAM and Aβ-42 interaction, is tentatively assigned to the peptide symmetric stretching vibration of carboxylate groups, and appears to be the most prominent spectral feature distinguishing toxic oligomers from the non-toxic Aβ-42 forms. This band was identified in the spectra of Aβ-42 adsorption on heptanethiol and MHP monolayers, while no clear perturbations were observed in the case of ODT monolayer.
authors.affiliation: Institute of Biochemistry, Vilnius University, Mokslininkų 12, LT-08662 Vilnius, Lithuania.
authors.forename: Vladislava
authors.initials: V
authors.lastname: Voiciuk
authors.forename: Gintaras
authors.initials: G
authors.lastname: Valincius
authors.forename: Rima
authors.initials: R
authors.lastname: Budvytytė
authors.forename: Algirdas
authors.initials: A
authors.lastname: Matijoška
authors.forename: Ieva
authors.initials: I
authors.lastname: Matulaitienė
authors.forename: Gediminas
authors.initials: G
authors.lastname: Niaura
mesh_terms: D000327:Adsorption; D016229:Amyloid beta-Peptides / Q000032:analysis* / Q000737:chemistry / Q000633:toxicity*; D004566:Electrodes; D006536:Heptanes / Q000737:chemistry; D020836:Protein Structure, Quaternary; D011726:Pyridinium Compounds / Q000737:chemistry; D013059:Spectrum Analysis, Raman; D013438:Sulfhydryl Compounds / Q000737:chemistry; D013499:Surface Properties
chemical_list: C545843:1-hexylpyridinium; D016229:Amyloid beta-Peptides; D006536:Heptanes; D011726:Pyridinium Compounds; D013438:Sulfhydryl Compounds; C055360:n-octadecyl mercaptan; C482407:2-heptanethiol