- [Show abstract] [Hide abstract] ABSTRACT: The aggregation of amyloid peptides into ordered fibrils is closely associated with many neurodegenerative diseases. The surfaces of cell membranes and biomolecules are believed to play important roles in modulation of peptide aggregation under physiological conditions. Experimental studies of fibrillogenesis at the molecular level in vivo, however, are inherently challenging, and the molecular mechanisms of how surface affects the structure and ordering of amyloid fibrils still remain elusive. Herein we have investigated the aggregation behavior of insulin peptides within water films adsorbed on the mica surface. AFM measurements revealed that the structure and orientation of fibrils were significantly affected by the mica lattice and the peptide concentration. At low peptide concentration (∼0.05 mg mL(-1)), there appeared a single layer of short and well oriented fibrils with a mean height of 1.6 nm. With an increase of concentration to a range of 0.2-2.0 mg mL(-1), a different type of fibrils with a mean height of 3.8 nm was present. Interestingly, when the concentration was above 2.0 mg mL(-1), the thicker fibrils exhibited two-dimensional liquid-crystal-like ordering probably caused by the combination of entropic and electrostatic forces. These results could help us gain better insight into the effects of the substrate on amyloid fibrillation.
- [Show abstract] [Hide abstract] ABSTRACT: Biological systems such as DNA and viruses have been frequently used as templates for the synthesis of functional nanomaterials. Here, we employed protein fibrils to direct the fabrication of one dimensional palladium nanostructures by incubating aged solution of sodium tetrachloropalladate(II) with pre-formed insulin fibrils for half an hour, followed by the hydrogen reduction at 600 °C. The size of the palladium nanoparticles was well controlled simply by varying the aging temperature of the sodium tetrachloropalladate(II) solution. The chemical identity of the formed palladium nanostructures along the fibrils was evaluated by X-ray photoelectron spectroscopy. The electrical properties of palladium nanoparticle were further examined by scanning conductance microscopy, which indicated that the metallic palladium nanostructures exhibited higher electrical resistance than expected, probably due to the palladium oxide within the palladium nanoparticle and the gaps between metallic palladium and palladium oxide.
- [Show abstract] [Hide abstract] ABSTRACT: Metal nanoparticles exhibit unique size- and spatial organization-dependent physical and chemical properties, and have a wide range of applications in various areas including single electron devices, chemical catalysts and biomedicines. In this paper, chains of palladium nanoparticles were obtained by incubating aged sodium tetrachloropalladate(II) with glucagon fibrils pre-deposited on a solid surface. AFM height profiles showed that the size of the palladium nanoparticles within the chains could be fine tuned in the range of 2 to 16 nm as a function of the concentration of the sodium tetrachloropalladate(II). Moreover, the coverage of the palladium nanoparticles along the fibrils was controlled simply by varying the incubation time. This method provides a facile approach for the construction of a palladium nanoparticle ensemble on biotemplates.