High Density of Line Pattern by Using De-Wetting During Soft-Lithography.

Here we prepared highly reliable and high density of pattern by using de-wetting induced soft-lithography. Additional line pattern arising from de-wetting of PS is generated in the protrusion of poly-dimethyl-siloxane (PDMS) mold by controlling thermal annealing time and molecular weight of PS. We found that such de-wetting and pattern formation is not dependent on the PS film thickness, but strongly influenced by molecular weight and annealing time of PS.

Gelation, phase behavior, and dynamics of β-lactoglobulin amyloid fibrils at varying concentrations and ionic strengths.

We have investigated the thermodynamic and dynamic behavior of multistranded β-lactoglobulin protein fibrils in water, by combining static, dynamic, and depolarized dynamic light scattering (SLS, DLS, DDLS), small angle neutron scattering (SANS), rheology, and cryogenic transmission electron microscopy (cryo-TEM). We focus on the region of the phase diagram at which ionic strength and concentration changes induce transitions in gelation and lyotropic liquid crystalline behavior. An increase in ionic strength, induced by NaCl salt, progressively causes the phase transitions from nematic (N) to gel (G) phases; a further increase causes the transition to a translucent phase and to a macroscopic phase separation, respectively.

Direct investigation of intracellular presence of gold nanoparticles via photothermal heterodyne imaging.

Nanotechnology as well as advanced microscopy can play a fundamental role in understanding biological mechanisms. Here we present a study that combines a new type of nanomaterial with a new type of microscopy and highlights the potential for gathering novel information about cell membrane penetration and cytosol local viscosity. On the material side, we used gold nanoparticles that have an ordered stripe-like arrangement of domains.

The fabrication of highly ordered silver nanodot patterns by platinum assisted nanoimprint lithography.

Silver has been widely used for optical sensing and imaging applications which benefit from localized surface plasmon resonance (LSPR) in a nanoscale configuration. Many attempts have been made to fabricate and control silver nanostructures in order to improve the high performance in sensing and other applications. However, a fatal mechanical weakness of silver and a lack of durability in oxygen-rich conditions have disrupted the manufacturing of reproducible nanostructures by the top-down lithography approach.

Interfacial activity and interfacial shear rheology of native β-lactoglobulin monomers and their heat-induced fibers.

Interfacial properties of native β-lactoglobulin monomers and their heat-induced fibers, of two different lengths, were investigated at pH 2, through surface tension measurements at water-air and water-oil interfaces and interfacial shear rheology at the water-oil interface. The applied heat treatment generates a mixed system of fibers with unconverted monomers and hydrolyzed peptides. The surface tension of this system at the water-air interface decreased more rapidly than the surface tension of native monomers, especially at short times (10(-3) to 10(2) s).

Fabrication of complex patterns with a wide range of feature sizes from a single line prepattern by successive application of capillary force lithography.

The variously shaped gold patterns can be generated from the polydimethylsiloxane (PDMS) mold using line patterns by the capillary force lithography (CFL) process, which is a kind of nanoimprint method following the two-cycle method. After fabrication of micro- or nanosized line patterns at the first cycle, the patterned substrate is used as a substrate for the second cycle of CFL. When the other stamp is placed on the first pattern, rotated by a certain angle with respect to the first stamp, only the overlapped parts remained dot-shaped after the etching process.

Effects of charge double layer and colloidal aggregation on the isotropic-nematic transition of protein fibers in water.

We investigate the effects of variable linear charge density and Debye length on the mesoscopic properties of beta-lactoglobulin fibers in water, by changing the pH and ionic strength, respectively. We determine the isotropic-nematic (I-N) transition by cross-polarized microscopy and quantify by atomic force microscopy the increasing tendency of the fibers to aggregate upon raising ionic strength. We then compare experimental I-N transitions with theoretical expected values based on Onsager theory.

Understanding amyloid aggregation by statistical analysis of atomic force microscopy images.

The aggregation of proteins is central to many aspects of daily life, including food processing, blood coagulation, eye cataract formation disease and prion-related neurodegenerative infections. However, the physical mechanisms responsible for amyloidosis-the irreversible fibril formation of various proteins that is linked to disorders such as Alzheimer's, Creutzfeldt-Jakob and Huntington's diseases-have not yet been fully elucidated. Here, we show that different stages of amyloid aggregation can be examined by performing a statistical polymer physics analysis of single-molecule atomic force microscopy images of heat-denatured beta-lactoglobulin fibrils.

Liquid crystalline phase behavior of protein fibers in water: experiments versus theory.

We have developed a new method allowing the study of the thermodynamic phase behavior of mesoscopic colloidal systems consisting of amyloid protein fibers in water, obtained by heat denaturation and aggregation of beta-lactoglobulin, a dairy protein. The fibers have a cross section of about 5.2 nm and two groups of polydisperse contour lengths: (i) long fibers of 1-20 microm, showing semiflexible behavior, and (ii) short rods of 100-200 nm long, obtained by cutting the long fibers via high-pressure homogenization.

Structure of heat-induced beta-lactoglobulin aggregates and their complexes with sodium-dodecyl sulfate.

We report on the conformation of heat-induced bovine beta-lactoglobulin (betalg) aggregates prepared at different pH conditions, and their complexes with model anionic surfactants such as sodium dodecyl sulfate (SDS). The investigation was carried out by combining a wide range of techniques such as ultra small angle light scattering, static and dynamic light scattering, small angle neutron scattering, small-angle X-ray scattering, electrophoretic mobility, isothermal titration calorimetry (ITC) and transmission electron microscopy. Three types of aggregates were generated upon heating betalg aqueous dispersions at increasing pH from 2.

Application of supramolecular nanostamping to the replication of DNA nanoarrays.

The rapid development of molecular biology is creating a pressing need for arrays of biomolecules that are able to detect smaller and smaller volumes of analytes. This goal can be achieved by shrinking the average size and spacing of the arrays' constituent features. While bioarrays with dot size and spacing on the nanometer scale have been successfully fabricated via scanning probe microscopy-based techniques, such fabrication methods are serial in nature and consequently slow and expensive.

Patterned arrays of au rings for localized surface plasmon resonance.

In this paper, we examined the characteristic behavior of localized surface plasmon resonances (LSPR) of Au dot and ring arrays in response to the selective binding of biomolecules. To do this, patterned arrays of Au rings and dots with various feature scales were fabricated over large areas by an imprint lithography technique. Our results showed that the LSPR spectra of the Au nanorings exhibited a blue shift with increase in the ring widths and asymptotically converged to those for Au nanodots.

Enhanced sensitivity of surface plasmon resonance (SPR) immunoassays using a peroxidase-catalyzed precipitation reaction and its application to a protein microarray.

We describe a method to improve the sensitivity of surface plasmon resonance (SPR) immunoassays using a horseradish peroxidase (HRP)-catalyzed precipitation reaction. The precipitation reaction catalyzed by HRP bound to the SPR biosensor surface via a sandwich immunoassay induced a shift in the SPR angle. Human interferon (IFN)-gamma at concentrations ranging from 0.

Nucleoside-based phospholipids and their liposomes formed in water.

Phospholipids and liposomes have been the subjects of considerable attention because of their importance in biological systems. We have efficiently synthesized novel nucleoside-based phospholipids in six-step sequences starting from their corresponding nucleosides. These nucleoside-based phospholipids self-assemble into liposome-like structures in aqueous solutions.

A fusion protein expression analysis using surface plasmon resonance imaging.

A surface plasmon resonance (SPR) imaging system was constructed and used to detect the affinity-tagged recombinant proteins expressed in Escherichia coli. With regards to model proteins, the hexahistidine-ubiquitin-tagged human growth hormone (His(6)-Ub-hGH), glutathione S-transferase-tagged human interleukin-6 (GST-hIL6), and maltose-binding protein-tagged human interleukin-6 (MBP-hIL6) expressed in E. coli were analyzed.