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This paper explores the size effect of zirconia particles on the catalysis of Ni metal for CO2 re-forming of methane. It is revealed for the first time that when the sizes of zirconia particles become samller than 25 nm, the oxide forms nanocomposite catalysts with size-comparable Ni-metal nanocrystals (10−15 nm). The nanocomposite catalysts show extremely stable catalysis, which is in strong contrast with the deactivating Ni catalyst supported on bigger zirconia particles (>25 nm). This raises the possibility of tailoring the catalytic behavior of oxide-supported metal catalysts by reducing the particle size of oxide to make high-performance nanocomposite catalysts.

The islet amyloid polypeptide (IAPP) is a hormonal factor secreted by the β-cells in the pancreas. Aggregation of misfolded IAPP molecules and subsequent assembly of amyloid nanofibrils are critical for the development of type 2 diabetes mellitus. In the physiological environment, amyloid aggregation is affected by the presence of interfaces such as cell membranes. The physicochemical properties of the interface dictates the interaction of the peptide with the surface, i.e., electrostatic and hydrophobic interactions on hydrophilic and hydrophobic surfaces, respectively. We have studied the influence of hydrophobicity on the surface-catalyzed assembly of IAPP on ultrasmooth hydrocarbon films grown on ion-beam-modified mica surfaces by atomic force microscopy. The contact angle θ of these surfaces can be tuned continuously in the range from ≤20° to ∼90° by aging the samples without significant changes of the chemical composition or the topography of the surface. On hydrophilic surfaces with a θ of ∼20°, electrostatic interactions induce the assembly of IAPP nanofibrils, whereas aggregation of large (∼2.6 nm) oligomers is observed at hydrophobic surfaces with a θ of ∼90°. At intermediate contact angles, the interplay between electrostatic and hydrophobic substrate interactions dictates the pathway of aggregation with fibrillation getting continuously delayed when the contact angle is increased. In addition, the morphology of the formed protofibrils and mature fibrils at intermediate contact angles differs from those observed at more hydrophilic surfaces. These results might contribute to the understanding of the surface-catalyzed assembly of different amyloid aggregates and may also have implications for the technologically relevant controlled synthesis of amyloid nanofibrils of desired morphology.

Copper enhances amyloid cytotoxicity and mediates human islet amyloid polypeptide (hIAPP) oligomerization; nickel, a redox inactive metal with similar protein binding affinity to copper, also mimics this effect, thereby demonstrating copper-mediated hIAPP cytotoxicity is due mainly to granular oligomer generation rather than ROS accumulation in type 2 diabetes.

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