Micropatterned fluoroalkylsilane monolayer surfaces with liquidphilic/liquidphobic area (line width 1-20 microm) were prepared with few defects by vacuum ultraviolet (VUV) photolithography. The anisotropic wetting of a macroscopic droplet with a 0.5-5 mm diameter on the micropatterned surfaces was investigated. The strong anisotropy of the contact angle and the sliding angle and droplet distortion for fluoroalkylsilane/silanol patterned surfaces was attributed to the difference in the energy barrier of wetting between parallel and orthogonal lines. The wetting anisotropy decreased with decreases in the liquidphilic area. Fluoroalkylsilane/alkylsilane patterned surfaces with small differences in the surface free energies of the components showed anisotropic wetting only for the low-surface-tension liquids.

A novel method for the control of peptide self-assembly has been developed by using synthetic triblock-type beta-sheet peptides composed of l- or d-amino acid, 1L and 1D, as building blocks. The peptides 1L and 1D self-assemble into beta-sheet nanofibers with left- and right-handed twists, respectively, under appropriate condition. On the other hand, the 1L/1D binary mixture was found to form only globular aggregates at the same condition. Thus, amyloid-like nanofiber formation and its nanostructure could be successfully regulated by the stereospecificity of the constituent peptide species.

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The molecular aggregation state of octadecylsiloxane monolayers on Si-wafer substrate surfaces prepared from octadecyltrimethoxysilane (OTMS) or octadecyltrichlorosilane (OTS) was investigated on the basis of grazing incidence X-ray diffraction (GIXD), Fourier transform infrared spectroscopy (FT-IR), contact angle measurement, field emission scanning electron microscopy (FE-SEM), and scanning force microscopy (SFM). The OTMS monolayer was prepared by using the chemical vapor adsorption (CVA) method, and the OTS monolayers, which were used as reference samples, were prepared either by chemisorption (OTS-S) or by the water-cast method (OTS-W). The GIXD, FT-IR, lateral force microscopic (LFM) measurements, and FE-SEM observation revealed that the alkyl chains in the OTMS monolayers prepared using the CVA method are in an amorphous state at room temperature. According to the LFM measurement, the transition temperature from the hexagonal crystalline phase to the amorphous phase was found to be ca. 333 K for the OTS-S monolayer prepared by the chemisorption method. However, the phase transition was not observed in the OTMS monolayer prepared by the CVA method. Also, the atomic force microscopic (AFM) observation and the contact angle measurement showed that the OTMS monolayer prepared by the CVA method has a uniform surface when compared to the OTS monolayers. These results indicated that organosilane compounds in the monolayer prepared by the CVA method were immobilized on the Si-wafer substrate surface in an amorphous state, which was quite different from the hexagonal crystalline state obtained by the chemisorption and water-cast methods.

Here, we report a novel, programmable, molecular self-assembling system to fabricate shape-specific, three-dimensional nanoarchitectures. Three types of simple 16-mer peptides consisting of hydrophobic Leu and hydrophilic Lys, LKL16, KLK16, and LK16, were prepared as building blocks for nanofabrications. A detailed analysis of the conformation and self-assembling mechanism was performed by using circular dichroism (CD), FTIR spectroscopy, and atomic force microscopy (AFM). A wide variety of self-assembled nanoarchitectures, such as beta-sheet-plates, beta-sheet-fibers, alpha-helix-particles, and alpha-helix-plates, could be fabricated by tuning the peptide sequence, reaction time, and solution pH. The ability to control the self-assembled nanostructures should provide a simple and/or essential insight into the mechanism of peptide aggregation, including amyloid formation, and it should be useful for the design of novel bio-related nanomaterials.

The self-assembly of peptides and proteins into beta-sheet-rich high-order structures has attracted much attention as a result of the characteristic nanostructure of these assemblies and because of their association with neurodegenerative diseases. Here we report the structural and conformational properties of a peptide-conjugated graft copolymer, poly(gamma-methyl-L-glutamate) grafted polyallylamine (1) in a water-2,2,2-trifluoroethanol solution as a simple model for amyloid formation. Atomic force microscopy revealed that the globular peptide 1 self-assembles into nonbranching fibrils that are about 4 nm in height under certain conditions. These fibrils are rich in beta-sheets and, similar to authentic amyloid fibrils, bind the amyloidophilic dye Congo red. The secondary and quaternary structures of the peptide 1 can be controlled by manipulating the pH, solution composition, and salt concentration; this indicates that the three-dimensional packing arrangement of peptide chains is the key factor for such fibril formation. Furthermore, the addition of carboxylic acid-terminated poly(ethylene glycol), which interacts with both of amino groups of 1 and hydrophobic PMLG chains, was found to obviously inhibit the alpha-to-beta structural transition for non-assembled peptide 1 and to partially cause a beta-to-alpha structural transition against the 1-assembly in the beta-sheet form. These findings demonstrate that the amyloid fibril formation is not restricted to specific protein sequences but rather is a generic property of peptides. The ability to control the assembled structure of the peptide should provide useful information not only for understanding the amyloid fibril formation, but also for developing novel peptide-based material with well-defined nanostructures.

We report a thermo-responsive polymer system showing widely tunable UCST/LCST behaviors based on amino acid-derived vinyl polymers. Four amino acids of Gly, Ala, Phe and Val and their methyl esters were employed for preparation of vinyl polymers, by considering hydrophobicity of the side chain group. The water solubility of these polymers was first examined, and as a result most of the polymers were soluble in water at a neutral pH, except the methylated Phe-based polymer and the Val-based polymers. The COOH-carrying Ala-based polymer displayed an upper critical solution temperature (UCST) behavior in water below pH 2.0 due to thermo-reversible hydrogen bonding of the pendent COOH groups, while the Gly-based polymer did not show any phase separation. The methylation of such COOH groups induced a lower critical solution temperature (LCST) behavior. Widely tunable UCST/LCST behaviors were achieved between 18 C and 73 C by using copolymers from different monomer combinations. Cross-linking of methylated Ala-based polymers gave a thermo-reversible hydrogel, which exhibited swelling and deswelling transitions at around the same temperature as the LCST of the corresponding homopolymer.

Herein, the formation of unique shape‐memory hydrogels that are composed of thermo‐responsive amino‐acid‐derived vinyl polymer networks is reported; these are readily prepared by radical copolymerization of N‐acryloyl glycinamide with commercially available cross‐linkers, namely, methylenebis(acrylamide) and poly(ethylene glycol) diacrylate. These hydrogels are transparent (>90% transmittance at 600 nm) and are comprised of 97–70 wt% water. Furthermore, these contain both chemical and physical cross‐linkages that are based on the multiple hydrogen bonds attained via amino acid units; this composition is aimed at generating opposing stimuli‐responsive characters, namely, chemically stable and thermo‐sensitive properties. A cooperative interplay of these two networks enables the hydrogels to exhibit a decent mechanical toughness (breaking strength ≈0.3 MPa and breaking elongation >600%) and a shape fix/memory capability. The temporary shape is easily fixed by cooling at 4 °C after deformation at high temperature, and it instantly recovers its original shape through reheating. Furthermore, a multi‐shape memory effect is achieved by incorporating the pH‐responsive N‐acryloyl alanine unit into the hydrogel system as a comonomer; in this system, three distinct shapes can be fixed through temperature and pH manipulations. This facilely attainable shape memory hydrogel has significant potential in various fields, such as soft actuators, sensors, and biomedical materials.