Amyloid β, Aβ(1–42), is a component of senile plaques present in the brain of Alzheimer’s disease patients and one of the main suspects responsible for pathological consequences of the disease. Herein, we directly visualize the Aβ activity toward a brain-like model membrane and demonstrate that this activity strongly depends on the Aβ oligomer size. PeakForce quantitative nanomechanical mapping mode of atomic force microscopy imaging revealed that the interaction of large-size (LS) Aβ oligomers, corresponding to high-molecular-weight Aβ oligomers, with the brain total lipid extract (BTLE) membrane resulted in accelerated Aβ fibrillogenesis on the membrane surface. Importantly, the fibrillogenesis did not affect integrity of the membrane. In contrast, small-size (SS) Aβ oligomers, corresponding to low-molecular-weight Aβ oligomers, created pores and then disintegrated the BTLE membrane. Both forms of the Aβ oligomers changed nanomechanical properties of the membrane by decreasing its Young’s modulus by ∼45%. Our results demonstrated that both forms of Aβ oligomers induce the neurotoxic effect on the brain cells but their action toward the membrane differs significantly.

Single‐atom catalysts (SACs) are highly enviable to exploit the utmost utilization of metallic catalysts; their efficiency by utilizing nearly all atoms to often exhibit high catalytic performances. To architect the isolated single atom on an ideal solid support with strong coordination has remained a crucial trial. Herein, graphene functionalized with nitrile groups (cyanographene) as an ideal support to immobilize isolated copper atoms G(CN)‐Cu with strong coordination is reported. The precisely designed mixed‐valence single atom copper (G(CN)‐Cu) catalysts deliver exceptional conversions for electrochemical methanol oxidation (MOR) and CO2 reduction (CO2RR) targeting a “closed carbon cycle.” An onset of MOR and CO2RR are obtained to be ≈0.4 V and ≈−0.7 versus Ag/AgCl, respectively, with single active sites located in an unsaturated coordination environment, it being the most active Cu sites for both studied reactions. Moreover, G(CN)‐Cu exhibited significantly lower resistivity and higher current density toward MOR and CO2RR than observed for reference catalysts.

Within the Waste2Fuel project, innovative, high-performance, and cost-effective fuel production methods are developed to target the “closed carbon cycle”. The catalysts supported on different metal oxides were characterized by XRD, XPS, Raman, UV-Vis, temperature-programmed techniques; then, they were tested in CO2 hydrogenation at 1 bar. Moreover, the V2O5 promotion was studied for Ni/Al2O3 catalyst. The precisely designed hydrotalcite-derived catalyst and vanadia-promoted Ni-catalysts deliver exceptional conversions for the studied processes, presenting high durability and selectivity, outperforming the best-known catalysts. The equilibrium conversion was reached at temperatures around 623 K, with the primary product of reaction CH4 (>97% CH4 yield). Although the Ni loading in hydrotalcite-derived NiWP is lower by more than 40%, compared to reference NiR catalyst and available commercial samples, the activity increases for this sample, reaching almost equilibrium values (GHSV = 1.2 × 104 h–1, 1 atm, and 293 K).

Phase-separated polymer blend films are an important class of functional materials with numerous technological applications in solar cells, catalysis, and biotechnology. These technologies are underpinned by the precise control of phase separation at the nanometer length-scales, which is highly challenging to visualize using conventional analytical tools. Herein, we introduce tip-enhanced Raman spectroscopy (TERS), in combination with atomic force microscopy (AFM), confocal Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS), as a sensitive nanoanalytical method to determine lateral and vertical phase-separation in polystyrene (PS)-poly­(methyl methacrylate) (PMMA) polymer blend films. Correlative topographical, molecular, and elemental information reveals a vertical phase separation of the polymers within the top ca. 20 nm of the blend surface in addition to the lateral phase separation in the bulk. Furthermore, complementary TERS and XPS measurements reveal the presence of PMMA within 9.2 nm of the surface and PS at the subsurface of the polymer blend. This fundamental work establishes TERS as a powerful analytical tool for surface characterization of this important class of polymers at nanometer length scales.

The electrochemical impedance spectroscopy (EIS) and polarization-modulation infrared reflection absorption spectroscopy (PM-IRRAS) techniques were employed to study the ionophore properties of valinomycin in a model floating bilayer lipid membrane (fBLM) in perchlorate supporting electrolytes with potassium and sodium cations. Valinomycin decreases the membrane resistance of the fBLM in KClO 4 solution by about 180 times, while it has a negligible effect on the membrane resistivity in NaClO 4 solution. The IR spectra indicate that valinomycin forms a complex with K + , but not with Na + . The valinomycin-K + complex adopts a small tilt angle with respect to the electrode surface normal and is well interdigitated between the acyl chains of the bilayer. The EIS and PM-IRRAS results indicate that valinomycin forms complexes with K + and transports K + across the lipid bilayer. This transport is potential independent and hence has a passive character.

No abstract

Neurodegeneration in Alzheimer's disease is associated with disruption of the neuronal cell membrane by the amyloid β (Aβ) peptide.

Lack of appropriate tools for visualizing cell membrane molecules at the nanoscale in a non‐invasive and label‐free fashion limits our understanding of many vital cellular processes. Here, we use tip‐enhanced Raman spectroscopy (TERS) to visualize the molecular distribution in pancreatic cancer cell (BxPC‐3) membranes in ambient conditions without labelling, with a spatial resolution down to ca. 2.5 nm. TERS imaging reveals segregation of phenylalanine‐, histidine‐, phosphatidylcholine‐, protein‐, and cholesterol‐rich BxPC‐3 cell membrane domains at the nm length‐scale. TERS imaging also showed a cell membrane region where cholesterol is mixed with protein. Interestingly, the higher resolution TERS imaging revealed that the molecular domains observed on the BxPC‐3 cell membrane are not chemically “pure” but also contain other biomolecules. These results demonstrate the potential of TERS for non‐destructive and label‐free imaging of cell membranes with nanoscale resolution.