In order to obtain nanopatterned surfaces, natural allophane particles originating from Japanese soils were immobilized as single particles on Si wafer substrates.When derived from aqueous suspensions, only a few nanoparticles were deposited and detected on the surface due to the weak adsorption of allophanes on the substrate. The amount of immobilized allophane was increased significantly, however, by using an organic solvent in combination with a micelle-based technique to suspend the allophane particles. The micelles were formed from a tailored, aliphatic diblock copolymer that was dissolved in toluene and contained several allophane particles. A cleaned silica chip was used as a substrate on which a monolayer of micelles was immobilized equidistant from each other by dip coating. To remove the polymer from the substrate and to produce free, single allophane nanoparticles, ultraviolet (UV) irradiation was used. After UV treatment, single allophane particles formed ring-shaped deposition patterns with a high surface density. Transmission electron microscopy (TEM) was used to verify the presence of single allophane nanoparticles in the Japanese samples which came from natural sources. The single allophane particles as well as the allophane-containing di-block copolymer micelles, both immobilized on Si substrates and TEM sample grids, were imaged by atomic force microscopy and TEM. In this way, the diameters of the single allophane particles, as well as the distances between the immobilized micelles and the particles and their topography on the substrates, were determined.

High hydrostatic pressure disruption of casein micelle isolates was studied by analytical ultracentrifugation and transmission electron microscopy. Casein micelles were isolated from skim milk and subjected to combinations of thermal treatment (85°C, 20 min) and high hydrostatic pressure (up to 676 MPa) with and without whey protein added. High hydrostatic pressure promoted extensive disruption of the casein micelles in the 250 to 310 MPa pressure range. At pressures greater than 310 MPa no further disruption was observed. The addition of whey protein to casein micelle isolates protected the micelles from high hydrostatic pressure induced disruption only when the mix was thermally processed before pressure treatment. The more whey protein was added (up to 5 g/l) the more the protection against high hydrostatic pressure induced micelle disruption was observed in thermally treated samples subjected to 310 MPa.

Intrinsic membrane proteins represent a large fraction of the proteins produced by living organisms and perform many crucial functions. Structural and functional characterization of membrane proteins generally requires that they be extracted from the native lipid bilayer and solubilized with a small synthetic amphiphile, for example, a detergent. We describe the development of a small molecule with a distinctive amphiphilic architecture, a “tripod amphiphile,” that solubilizes both bacteriorhodopsin (BR) and bovine rhodopsin (Rho). The polar portion of this amphiphile contains an amide and an amine-oxide; small variations in this polar segment are found to have profound effects on protein solubilization properties. The optimal tripod amphiphile extracts both BR and Rho from the native membrane environments and maintains each protein in a monomeric native-like form for several weeks after delipidation. Tripod amphiphiles are designed to display greater conformational rigidity than conventional detergents, with the long-range goal of promoting membrane protein crystallization. The results reported here represent an important step toward that ultimate goal.