By simultaneous coherent anti-Stokes Raman scattering (CARS) and 2-photon fluorescence microscopy of Thioflavin-S stained Alzheimer´s diseased human brain tissues, we show evidence of lipid deposits co-localizing with fibrillar β-amyloid (Aβ) plaques. Two lipid morphologies can be observed; lamellar structures and coalescing macro-aggregates of sub-micron sizes to ~25 μm. No significant lipid deposits were observed in non-fibrillar, diffuse plaques identified by Aβ immuno-staining. CARS microscopy of unlabeled samples confirms the lamellar and macro-aggregate lipid morphologies. The composition of the plaques was analyzed by CARS microspectroscopy and Raman microscopy; vibrational signatures of lipids with long acyl chains co-localize with the β-sheet vibrations. The lipid fluidity was evaluated from the CARS spectra, illustrating that the lipid composition/organization varies throughout the plaques. Altogether this indicates close amyloid-lipid interplay in fibrillar Aβ plaques, rendering them more dynamic compositions than previously believed and, hence, potential sources of toxic oligomers.

The adsorption and photochemical properties of reduced and stoichiometric anatase TiO 2 nanoparticles, prepared by annealing in vacuum and air, respectively, at different temperatures up to 500 °C and 2 days have been investigated. Combined X-ray diffraction and Raman spectroscopy results suggest that vacuum annealing leads to a defective, oxygen vacancy rich surface region with an accompanying decrease of the crystalline core. The surface chemical properties of the reduced and calcined TiO 2 nanoparticles were studied by means of SO 2 adsorption measured by in situ diffuse reflectance Fourier transform spectroscopy. On pristine TiO 2 nanoparticles SO 2 adsorption leads to a broad absorbance band centered at 1140 cm −1 . In contrast, SO 2 does not adsorb on stoichiometric TiO 2 obtained after long-term annealing in air at 500 °C. However, after the same heat treatment in vacuum, SO 2 is shown to bind strongly on well-defined adsorption sites associated with a narrow absorbance band at 1150 cm −1 . The increased adsorption on reduced TiO 2 is attributed to formation of subsurface oxygen vacancies and reactive Ti 3+ species at the surface that promote SO 2 bonding. A surface-sulfite species (HSO 3 − ) was identified as the major adsorbate on both the as-prepared and the vacuum-annealed sample, and a formation mechanism involving reaction with hydrogen from surface hydroxyl groups is proposed. During UV illumination, SO 2 is photoadsorbed on TiO 2 during SO 2 exposure in an inert He gas atmosphere. In contrast to dark SO 2 adsorption, this reaction does not involve surface defects, since the concentration of photoadsorbed SO 2 did not significantly change on the deeply reduced TiO 2 nanoparticles. On the basis of these findings, a new mechanism for the formation of surface-bound SO 3 2− during UV illumination on the stoichiometric surface is proposed, which should be generally applicable for other similar adsorbates and semiconducting oxides.

Hybrid synthesis of Cu2O/ZnO nanorod heterojunction exhibiting enhanced interfacial charge transfer and photocatalytic activity comprising hydrothermal synthesis step of ZnO nanorods followed by advanced gas deposition of Cu nanoparticles.

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