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“Breath figure formation” during the casting process of polymer solutions under high atmospheric humidity provides honeycomb-patterned polymer films (honeycomb films) with regularly arranged micropores. The development of production technology for large-area honeycomb films is indispensable for their various applications. Manufacturing equipment consisting of three zones (for casting, humidification, and drying of polymer solutions) for successive formation of large-area honeycomb films was newly designed and constructed. By using this equipment, physicochemical experimental parameters, e.g., the surface temperature of polymer solutions, dew point of the humidification zone, humidification time, and interfacial tension between water and the polymer solution, were effectively changed to optimize the density and size of condensed water droplets. Large-area honeycomb films were formed by a roll-to-roll process. Herein, recent developments in biomedical applications of honeycomb films are described. “Breath figure formation” during the casting process of polymer solutions under high atmospheric humidity provides honeycomb-patterned polymer films (honeycomb films) with regularly arranged micropores. The development of production technology for large-area honeycomb films is indispensable for their various applications. Manufacturing equipment consisting of three zones (for casting, humidification, and drying of polymer solutions) for successive formation of large-area honeycomb films was newly designed and constructed. By using this equipment, physicochemical experimental parameters, e.g., the surface temperature of polymer solutions, dew point of the humidification zone, humidification time, and interfacial tension between water and the polymer solution, were effectively changed to optimize the density and size of condensed water droplets. Large-area honeycomb films were formed by a roll-to-roll process. Herein, recent developments in biomedical applications of honeycomb films are described.

Inorganic nanoparticles are an attractive material that shows unique properties that differ from their bulk counterparts. Assembly of nanoparticles with soft materials is an effective approach to l...

In this study, we demonstrate that the plasmonic properties of gold nanorods (GNRs) electrostatically adsorbed on a DNA brush substrate are reversibly controlled by changes in NaCl concentration. This plasmonic change results from GNR assembly/disassembly in a DNA brush layer. In addition, we show that this active plasmonic system exhibits intense and switchable chiroptical properties.

The development of a strategy for the assembly of nanoscale building blocks, in particular, anisotropic nanoparticles, into desired structures is important for the construction of functional materials and devices. However, control over the orientation of rod-shaped nanoparticles on a substrate for integration into solid-state devices remains challenging. Here, we report a strategy for the fabrication of finely aligned gold nanorod (GNR) arrays using polymer (DNA) brushes as a nanoscale template. The gold nanorods modified with cationic surface ligands were electrostatically adsorbed onto the DNA brush substrates under various conditions. The orientational behavior of the GNRs was examined by spectral analyses and transmission electron microtomography (TEMT). As a result, we found several important factors, such as moderate interaction between GNRs and polymers and polymer densities on the substrate, related to the vertical alignment of GNRs on the substrates. We also developed a purification method to remove the undesired adsorption of GNRs onto the arrays. Finally, we have succeeded in the fabrication of extensive vertical GNR arrays of high quality via the easy bottom-up process.

Tropomyosin (Tpm) is a two-stranded parallel α-helical coiled-coil protein, and studying its structure is crucial for understanding the nature of coiled coils. Previously, we found that the N-terminal half of the human skeletal muscle α-Tpm (α-Tpm 140) was less structurally stable in the presence of phosphate ions than the coiled-coil protein carrier (CCPC) 140 variant with 18 mutated residues, in which all amino acid residues located at the interface between the two α-helices were completely conserved. A classical hypothesis explains that interhelical interactions stabilize the coiled-coil structure. In this study, we tested the hypothesis that the structural stability of Tpm and its variant is governed by the binding of multivalent ions that form a bridge between charged side chains located at positions b, c, and f of the heptad repeat on a single α-helical chain. We found that the structural stability of α-Tpm 140 and CCPC 140 markedly increased upon addition of divalent cations and divalent anions, respectively. We also clarified that the structural stability of the α-Tpm 140/CCPC 140 heteromeric coiled-coil molecule was governed by the stability of a less stable α-helical chain. These results demonstrated that the entire structural stability of Tpm is determined by the stability of a single α-helix. Our findings provide new insights into the study of the structure of coiled-coil proteins.

This paper presents the thermoresponsive assembly behaviors of gold nanoparticles (AuNPs; 3, 5, and 10 nm in diameter) that are coated with a self-assembled monolayer of oligo(ethylene glycol) (OEG) ligands terminated with alkyl heads. AuNPs (5 nm in diameter) coated with OEG ligands without an alkyl head did not assemble within a temperature range from 20 to 70 °C. However, AuNPs coated with ethyl, iso-propyl, and propyl-headed OEG AuNPs afforded assembly at temperatures of 56, 33, and 19 °C, respectively, indicating that the assembly temperature can be tuned over a wide range by slight changes in the hydrophobicity of the alkyl head. Almost no hysteresis during the heating/cooling cycles was observed for the assembly/disassembly process. The diameter of the AuNPs also affected the assembly temperature, with increases in the diameter of the AuNP affording a lower assembly temperature. The ligand with the shorter alkyl tail length provided the lower assembly temperature of AuNPs than the ligand with longe...

The self-assembly of gold nanoparticles (GNPs) into a defined structure, particularly hollow capsule structures, provides great potential for applications in materials science and medicine. However, the complexity of the parameters for the preparation of those structures through self-assembly has limited access to critical mechanistic questions. With this in mind, we have studied GNP vesicle (GNV) formation through self-assembly by the surface modification of GNPs with low-molecular-weight ligands. Here, we successfully prepared GNVs composed of GNPs with a diameter of 30 nm by surface modification with carboxylic acid-terminated fluorinated oligo(ethylene glycol) ligands (CFLs). As the carboxylic acid has two states (protonated and deprotonated), the balance of the attraction and repulsion between GNPs covered with CFLs is tunable. Sodium carboxylate-terminated fluorinated oligo(ethylene glycol) ligands (SCFLs) provided smaller GNVs than did CFLs at 0.8 × 1011 NPs/mL. Time-course study revealed that CFL-...

The self-priming synthesis of multiply modified DNA by the extension of repeating unit duplex “oligoseeds” provides a source of versatile DNA. Sterically-demanding nucleotides 5-Br-dUTP, 7-deaza-7-I-dATP, 6-S-dGTP, 5-I-dCTP as well as 5-(octadiynyl)-dCTP were incorporated into two extending oligoseeds; [GATC]5/[GATC]5 and [A4G]4/[CT4]4. The products contained modifications on one or both strands of DNA, demonstrating their recognition by the polymerase as both template (reading) and substrate (writing). Nucleobase modifications that lie in the major groove were reliably read and written by the polymerase during the extension reaction, even when bulky or in contiguous sequences. Repeat sequence DNA over 500 bp long, bearing four different modified units was produced by this method. The number, position and type of modification, as well as the overall length of the DNA can be controlled to yield designer DNA that offers sequence-determined sites for further chemical adaptations, targeted small molecule binding studies, or sensing and sequencing applications.

Stimuli-responsive assembly of gold nanoparticles (AuNPs) with precise control of the plasmonic properties, assembly size, and stimuli responsivity has shown potential benefits with regard to biosensing devices and drug-delivery systems. Here we present a new pH-responsive coassembly system of oligo(ethylene glycol) (OEG)-coated AuNPs with anionic polymers as an external mediator via hydrogen bonding in water. Hydrogen-bond-driven coassemblies of OEG-AuNPs with poly(acrylic acid) (PAA) were confirmed by the monitoring of plasmonic peaks and hydrodynamic diameters. In this system, the protonation of anionic polymers on change in pH triggered the formation of hydrogen bond between the OEG-AuNPs and polymers, providing sensitive pH responsivity. The plasmonic properties and assembly size are affected by both the ratio of PAA to AuNPs and the molecular weight of PAAs. In addition, the attachment of hydrophobic groups to the surface ligand or anionic polymer changed the responsive pH range. These results demonstrated that the coassembly with an external mediator via hydrogen bonding provides a stimuli-responsive assembly system with tunable plasmonic properties, assembly size, and stimuli responsivity.

Surface modification with polymer is widely applied to various kinds of applications. Recently, polymer brushes, which is a layer of polymers attached with one end to a surface, have attracted much attention as functionalized surfaces. In particular, ionic polymer brushes provide ultra-low friction or anti-fouling because they act as highly hydrated soft film. Almost ionic polymer brushes have been prepared from synthetic polymers. Few biopolymers have been investigated for polymer brush studies. DNA which is one of ionic biopolymers has unique functions and conformations which synthetic polymers don’t have. We found that cationic gold nanorods (30 x 10 nm) were adsorbed to DNA bush (148 bp) prepared on a glass surface in an aqueous solution by observation using extinction spectra. When the cationic charge density of gold nanorods were decreased, nanorods were immobilized perpendicularly to the substrate by binding to DNA elongated. This indicates that self-assembled alignment of gold nanorods can be achieved by using DNA brush. Formed aligned gold nanorods can be used for plasmonic color analysis.

Gold nanoparticles (GNPs) show promise as both drug and imaging carriers with applications in both diagnosis and therapy. For the safe and effective use of such gold nanomaterials in the biomedical field, it is crucial to understand how the size and shape of the nanomaterials affect their biological features, such as in vitro cellular uptake speed and accumulation as well as cytotoxicity. Herein, we focus on triangular gold nanoparticles (TNPs) of four different sizes (side length 46, 55, 72, and 94 nm; thickness 30 nm) and compare the cellular internalization efficiency with those of spherical nanoparticles (SNPs) of various diameters (22, 39, and 66 nm). Both surfaces were coated with anionic thiol ligands. Inductively coupled plasma-emission spectrometry (ICP-ES) data demonstrated that TNPs with longer sides showed higher levels of uptake into RAW264.7 and HeLa cells. On the other hand, in the case of SNPs, those with smaller diameters showed higher levels of uptake in both cells. Our results support the notion of a reverse size dependence of TNPs and SNPs in terms of cellular uptake. For HeLa cells, in particular, 20-fold more efficient internalization was observed for TNPs with longer sides (72 nm side length) compared to SNPs (66 nm) with a similar surface area. These results highlight the importance of the shape of nanomaterials on their interactions with cells and provide a useful guideline for the use of TNPs.

In conventional cell culture systems, trypsin is generally used for cell harvesting. However, trypsin damages the cells due to the nonselective degradation of proteins on the cell surface. This is a critical issue for cell culture systems. Therefore, an alternative cell culture system with the lowest possible impact on cells is desired. In this paper, we have focused on DNA as a sacrificial layer and DNase as an alternate enzyme instead of trypsin. DNase ought not to result in damage to or stress on cells as it only hydrolyzes DNAs while the plasma membrane and extracellular matrices are basically composed of lipids, proteins, and glycosides. Therefore, we fabricated DNA-grafted substrates as cell culture dishes and evaluated this novel cell culture system. As a result, we were able to culture several types of mammalian cells on the DNA-grafted substrates, with the cells harvested using DNase with only little damage to the cells. This cell culture system could provide a breakthrough in cell culturing technology.

Although progress has been made in the construction of single-electron devices (SEDs), few of the reported approaches have proved practically applicable, mainly owing to their cost-ineffectiveness and need for sophisticated instrumentation. Herein, a conceptually new method for fabricating SEDs through the metallization of divalent DNA-nanoparticle conjugates is described. Specifically, divalent DNA copolymers that are conjugated to gold nanoparticles (AuNP) were synthesized by application of the enzymatic extension of DNA conjugated on quantum-sized AuNPs. This conjugate structure allows the distance between the resulting poly(dG)-poly(dC) and the AuNP to be controlled by an ssDNA spacer. To afford poly(dG)-poly(dC) sequence-specific metal deposition, Cisplatin capable of specific chemisorption on the poly(dG)-poly(dC) is incubated with the divalent DNA copolymer–AuNP conjugates, followed by reduction of the Cisplatin to Pt metal at base resolution. As a result, AuNPs separated from the Pt “electrodes” by the ssDNA barriers in a single conjugate could be created as a double-tunnel junction for SEDs. This study is thought to be an important step toward the programmable organization of DNA for use in SEDs.

The effects of water on the mechanical properties of synthetic hydrophilic polymers with double-network (DN) structures were studied under different relative humidities (RH). It was found that they could sustain nearly the same high Young’s modulus as dry DN polymers in the RH range 10–80% (water content 3–17 wt %), that is, more than 102 MPa. However, when the RH exceeds 80%, DN polymers abruptly absorb large amounts of water (water content 90 wt %) and transform to a highly water-swollen “gel state” with a decrease in the Young’s modulus of 3 orders of magnitude. Spectroscopic analyses revealed that water molecules below RH 80% are strongly bound to hydrophilic moieties with highly restricted mobility; water under such states improves rather than reduces mechanical properties by behaving as a plasticizer. DN polymers capable of sustaining high mechanical properties, even under RH 80%, have potential uses as hydrophilic materials.

We demonstrate here a creation of superhydrophobic and superhydrophilic patterned surface by using reactive ion etching (RIE) of silicon with a self-organized porous polymer structures and UV-O3 treatments through the photo-mask. Honeycomb-patterned films of polystyrene and amphiphilic polymer were prepared by casting of their chloroform solution. After UV-O3 treatment, honeycomb-patterned films were fixed on silicon substrates up side down with Poly (vinyl alcohol) solution. After peeling of the bottom layer of the honeycomb-patterned films, porous polymer masks were formed on the silicon substrate. After RIE, the silicon nanospike-array structure was obtained. Water contact angles on the silicon nanospike-array structures were c. a. 165 degree. From the results of X-ray photoelectron spectrum of the silicon nanospike-structures, fluorine was detected. The result suggests that superhydrophobicity was originated by absorbed fluorocarbons on the surface of the silicon nanospike-array structures and their surface structures. After UV-O3 treatment with photo-masks, fluorine was partially removed at irradiation area, and the area shows superhydrophilicity. These results suggest that we can easily design superhydrophobic and superhydrophilic patterned surfaces by UV-O3 treatment through photo-masks.

Self-organized honeycomb-patterned polymer films were prepared by using condensed water droplet arrays as templates. Porous polymer masks for dry etching were easily prepared on Si substrates by peeling off the honeycomb-patterned films. After dry etching, hexagonally-arranged micro-pores were formed on the surface of Si substrates.

We have reported that honeycomb-like porous polymer films, which were spontaneously formed in the casting of polymer solutions under humid conditions, were converted into honeycomb-like metal meshes by electroless plating. In this report, the unique optical properties of these meshes will be discussed. Silver-coated honeycomb mesh films were prepared by selforganization and electroless plating methods. The incident angle dependence of their transparency, and their electrical conductivity were measured. The metallized film had limited viewing angle.

We describe a graft-type modification of a solid surface to be able to immobilize unprotected carbohydrates with a desired pattern. Water soluble carbohydrate-trapping polymers were grown from a so...

This study aims at the synthesis of Janus gold nanoparticles (Janus GNPs) with hydrophilic/hydrophobic faces by a simple ligand exchange reaction in an homogeneous system and at the elucidation of the self-assembled structures of the Janus GNPs in water. As hydrophilic surface ligands, we synthesized hexaethylene glycol (E6)-terminated thiolate ligands with C3, C7, or C11 alkyl chains, referred to as E6C3, E6C7, and E6C11, respectively. As a hydrophobic ligand, a butyl-headed thiolate ligand C4-E6C11, in which a C4 alkyl was introduced on the E6C11 terminus, was synthesized. The degree of segregation between the two ligands on the GNPs (5 nm in diameter) was examined by matrix-assisted laser desorption/ionization time-of fright mass spectrometry (MALDI-TOF MS) analysis. We found that the choice of immobilization methods, one-step or two-step addition of the two ligands to the GNP solution, crucially affects the degree of segregation. The two-step addition of a hydrophilic ligand (E6C3) followed by a hydrophobic ligand (C4-E6C11) produced a large degree of segregation on the GNPs, providing Janus-like GNPs. When dispersed in water, these Janus-like GNPs formed assemblies of ∼160 nm in diameter, whereas Domain GNPs, in which the two ligands formed partial domains on the surface, were precipitated even when the molar ratio of the hydrophilic ligand and the hydrophobic ligand on the surface of the NPs was almost 1:1. The assembled structure of the Janus-like GNPs in water was directly observed by pulsed coherent X-ray solution scattering using an X-ray free-electron laser, revealing irregular spherical structures with uneven surfaces.

Solution-phase synthesis and post-synthetic bio-modification have continued to play a dominant role in preparation of nanostructured biomaterials. Heterogeneous nucleation and growth that occur much more often in nature, however, remain rarely explored in nano-biomaterials research. We have newly developed a DNA-modulated photoconversion approach to uniform silver nanoparticles that afford DNA-directed recognition and multi-mode imaging. The present study was aimed at understanding the rapid heterogeneous nucleation and growth of AgNPs at the solid–liquid interface with the aid of DNA. Dynamic changes in absorbance, size and morphology of silver nanostructures were monitored and analyzed to clarify the growth kinetics, which indicated a synthetic route involving synchronous growth of silver nanostructures and the fragmentation and consumption of AgCl. Various stabilizers, including polymer and amino acids, were assessed and compared with respect to the efficacy in photoconversion of AgCl. DNA was found to offer the best monodispersity and the smallest diameter for the resultant AgNPs, due to its strong interactions to silver species as well as excellent charge dispersion ability. By controlling the physicochemical property of DNA through choice of pH and ionic strength, we have demonstrated tunable structure and composition of the nanoparticles.

Deoxyribonucleic acid (DNA) has a lot of characteristic features, e.g., anionic polyelectrolyte, molecular recognition and condensed π electron. Therefore, it is expected to be applied as functional materials in not only biological but also physical fields. In this report, we attempted to prepare water-insoluble DNA films by mixing DNA and photolinkable polymer, aiming at the fabrication of bio-functionalized hydrogel films. For this purpose, photocrosslinkable polyvinyl alcohol (azide-unit pendant water-soluble photopolymer; AWP) was used. An aqueous DNA and AWP mixture was cast onto glass substrates. Irradiation of UV light on it for certain minutes provided a hydrogel film by photocrosslinking between DNA and AWP. When the formed hydrogel film was soaked in pure water for 1 day, large expansion of the film was observed. The expanded film was shrunk by soaking it in aqueous NaCl or CTAB solutions. The expansion and shrinkage mechanism of the film was attributed to the penetration of water into the gap between the film and the substrate due to osmotic pressure. This phenomenon can be applied to the fabrication of gel devices, e.g., a novel biosensor and drug delivery system.

The phenomenon of molecular recognition including further function is common in nature. Host-guest complexation occurring at Langmuir monolayers has been investigated in detail similarly to molecular recognition in solutions. Langmuir monolayers at the air-water interface provide a unique environment for molecular recognition. Characteristic binding efficiency and selectivity of water-soluble substrates by specific pairing of hydrogen bonding have been found for functionalized monolayers at the air-water interface. Hydrogen bonding network formation between a functionalized monolayer and a substrate enables cleavage of the head group of an amphiphile forming the monolayer by hydrolysis of a C=C double bond that links the head group to the hydrophobic tail. Molecular organization termed “molecular recognition-directed self-assembly” has been demonstrated through complementary base-pairing in monolayers at the air-water interface. Controlling of molecular arrangement of nucleobase amphiphiles in Langmuir monolayers has been attempted by using complementary base-pairing with sequence-designed oligonucleotides as a molecular template. This unique molecular recognition should be useful for nanotechnology.

Microporous polymer films are attractive materials with potential application in the fields of electronics, photonics, and biotechnology. Chemical and thermal stabilities of the microporous polymer films are required for their materials application. Besides preparation by conventional photolithography, we have reported that honeycomb-patterned porous polymer films are prepared by a method utilizing the condensation of small water droplets on solutions of amphiphilic copolymers. Here, we show preparation of honeycomb-patterned microporous films of a thermally and chemically stable material, polyimide. A water-template-assisted honeycomb structure was formed from a polyion complex of polyamic acids and dialkylammonium salt. The pore size of films was controlled by the casting volume of polymer solution. The patterned polyion complex film converted into polyimide by simple chemical treatment, keeping the porous structure. Self-supporting microporous polyimide films are fabricated. The honeycomb-structured fi...

This article describes novel three methods for micro-patterning of cell adhesive ligands by using the self-organized honeycomb-patterned structure formed by the simple cast method. A first method is a direct preparation of a patterned film by casting an amphiphilic polymer containing lactose residue which is one of cell adhesive ligands. A benzene solution of the amphiphilic polymer was cast at high humidity on a glass substrate. Atomic force microscopy (AFM) observation of the film showed that a honeycomb pattern with microporousness with as large as micrometer size in diameter was formed. The film was immersed into an aqueous fluorescence-labeled lectin solution to investigate the distribution of lactoses on the patterned film. Consistence of a fluorescence image of the lectin bound film with the honeycomb pattern showed that the lactose residues were existed not at the holes but at the rims of the honeycomb-patterned film. A second method is to immobilize gelatin, which is one also one of cell adhesive ligands, on the honeycomb-patterned film by chemical reaction. A honeycomb-patterned film was prepared from chloroform solution of an amphiphilic polymer containing reactive succinimide ester groups, and then the film was immersed into an aqueous fluorescence-labeled gelatin solution to introduce gelatin on the film surface. Immobilization of gelatin onto honeycomb-patterned film was confirmed by the fluorescence microscope. A third method is another way to introduce gelatin onto the honeycomb film by the specific avidin-biotin interaction. A honeycomb-patterned film was prepared from amphiphilic polymer containing biotin residues and dodecyl groups, and then the film was immersed into a avidin solution and a biotinylated fluorescence labeled gelatin solution successively. By the fluorescence microscopic observation of the film, gelatin was confirmed to be immobilized at the rims of the honeycomb pattern via the avidin-biotin interaction. Cell culture was performed on the gelatin immobilized patterned film prepared by second method. Bioactivity of gelatin immobilized honeycomb-patterned film was confirmed by adhesion of cell onto the film.

Amphiphilic NaY zeolite particles were prepared by a partial modification of the external surface of NaY with alkylsilyl groups. When the particles were added to a mixture of aqueous hydrogen peroxide and normal alkene, they were feasibly located just at the liquid−liquid phase boundary and efficiently catalyzed epoxidation of the alkenes even without stirring. Fluorescence microscopic observation of these particles selectively modified with fluorescent dye revealed that each particle has a bimodal amphiphilic surface structure; one side of the external surface is hydrophilic and the other is hydrophobic.

The formation of the base pair adenine-uracil at a water−solid interface, at an immobilized monolayer of adenine disulfide with adenine groups exposed to the very surface, respectively, is shown here. To overcome the steric hindrance of tightly packed adenine groups in a pure adenine thiolate monolayer on gold, the formation of self-assembled monolayers out of a binary mixture of the adenine disulfide and CH3- or OH-terminated thiols are investigated. Electro-chemical investigations, surface plasmon spectroscopy (PSP, plasmon surface polariton), multimode waveguide-PSP-coupling spectroscopy, contact angle measurements, and spontaneous desorption time-of-flight mass spectrometry were used to characterize the monolayers. The specific base pairing was investigated for a variety of monolayer compositions. A specific base pairing was successful for an optimized mixed adenine/OH-terminated thiol monolayer. Nevertheless unspecific binding is a problem.

Fluorescence quenching of an amphiphilic intercalator (an electron donor, C18AO+) by an amphiphilic viologen (an electron acceptor. C12BhpC5V2+) in a cationic monolayer of 2C18N+2C1 was enhanced when the monolayer formed polyion complexes with double-stranded polynucleotides at the air-water interface. Fluorescence intensity and quenching efficiency were strongly depended on structure of polynucleotides.

Mesoscopic two-dimensional patterns, regular dots, stripes, and honeycomb networks are formed when dilute organic solutions of polymers are cast on solid surfaces. Dynamic patterns, so-called “dissipative structures”, formed in the non-equilibrium thermodynamic process of solvent evaporation, are fixed as the two-dimensional polymer patterns on substrates. Some photonic and electronic applications of the mesoscopic polymer patterns are described in this article.

Hierarchical mesoscopic structures of the nanoscopic supramolecular assemblies, which consist of polyelectrolytes and bilayer-forming amphiphiles, are prepared by a simple and new solvent-casting method. Submicron scale 2-D structures, e.g. regular dots, stripes, and networks, are formed when highly diluted organic solutions of polymer assemblies are cast on solid surfaces. Dynamic mesoscopic regular structures, the so-called ‘dissipative structures’, formed in the non-equilibrium processes of solvent-casting are fixed as hierarchically structured polymer assemblies.

Lipase OF from Candida showed only low enantioselectivity for esterification of ( R )- or S -1-phenylethanol with lauric acid ( v R v S = 5.5 ). However, when lipase OF was imprinted with a substrate analogue such as ( R )-1-phenylethanol and then coated with synthetic glycolipid molecules, the imprinted lipid-coated lipase shows a large enantioselectivity for the esterification in anhydrous isooctane ( v R v S = 77 ). When the native lipase OF was imprinted by the same procedure, the enantioselectivity hardly changed. The lipid coating was important to keep the imprinted structure as well as to solubilize enzymes in organic solvents. The improved enantioselectivity was confirmed from Michaelis-Menten kinetics as due to the intramolecular catalytic reaction and not the substrate binding process. The improved enantioselectivity reverts to the original non-imprinted value if kept in the organic solvents at high temperatures for days.

A series of FITC-labeled hydrophobic molecules (1−8) were prepared, and their cellular uptakes have been investigated using cell-cycle-synchronized HeLa cells. The cellular membrane permeability of compounds strongly depended on both the chemical structure and the cell-cycle phase. In the G1/S phase, branched hydrocarbon-containing 3 and cis-olefin-containing 2 and 8 were efficiently internalized into cells by passive diffusion. In contrast, linear alkyl chain-containing 1 and 7 were retained on the membrane without rapid internalization. In the M phase, rapid permeation was suppressed for all molecules.

A two-dimensional micron-sized honeycomb structure was formed when a chloroform solution of an amphiphilic polymer was cast on solid surfaces at high atmospheric humidity. This simple method is widely applicable for patterning of molecular aggregates on solid surfaces. Mesoscopic patterns are demonstrated to be formed spontaneously from a variety of amphiphilic polyion complexes, amphiphilic covalent polymers, and organic–inorganic hybrid materials. Size and structure of the patterns can be regulated by concentration, atmospheric humidity, etc.

We investigated electric conductivities of poly nucleic acid-amphiphile polyion complex monolayers. The polyion complex monolayers were prepared by spreading of dialkylammonium salt on aqueous solutions of various poly nucleic acids. The complex monolayers were compressed at the air–water interface and transferred on comb-shaped Au-electrode substrates by vertical lifting method. I–T plots of the complex monolayers, which were measured under applying direct voltage, suggested that the complex monolayers were dielectric substances. The I–V plots indicated that the conductivity of the monolayer depended on the species of poly nucleic acids. Based on the ac impedance analysis of those monolayers, the bulk resistance of those monolayers was estimated from the complex impedance plane plots.

The effect of 5′-phosphorylation at nicks on DNA stabilization was measured through the formation of DNA multiassemblies consisting of 40-mer half-sliding complementary oligonucleotides, which had ...

In our previous paper, secondary-amine appended cationic polymer 1 was used as a scaffold to display artificial receptors on a cell surface (R. Kamitani et al., ChemBioChem, 2009, 10, 230). This polymer can be retained on the cell surface for more than 30 min before being slowly internalized into the cells. In this study, our aim is to achieve the efficient internalization of quantum dots (QDs) into target cells via artificial receptors on the polymer. As a receptor molecule, N-acetylglucosamine (GlcNAc) moieties were introduced into the polymer, and GlcNAc binding protein-displaying QDs were used as a ligand. We found that ligand-presenting QDs could be internalized effectively into cells via polymer-mediated endocytosis, whereas QDs were not internalized into untreated cells. These data suggest that our method based on cell-surface engineering using polymers affords a new approach to the delivery of various poorly permeable nanoparticles into cells.

We demonstrate here a creation of a novel biomimetic bi-functional surface by using dry etching of silicon with a self-organized porous polymer. The novel silicon structures with hierarchical nanospike-array structures covered with fluorocarbons were fabricated by dry etching of silicon through the porous polymer masks. The anti-reflection and superhydrophobic properties were realized due to their large surface areas and low surface energies. These masks and silicon substrates offer great advantages and are suitable for various practical applications, including high efficiency solar cells.

Hexagonally packed water droplets condensed on a polymer solution are potential templates for the formation of honeycomb-patterned porous polymer films. A small number of surface-active molecules is indispensable for the stabilization of water droplets during solvent evaporation. Biocompatible surfactants; e.g., phospholipids, are required for the fabrication of biodegradable honeycomb-patterned polymer films, which can be used as novel biomedical materials, mainly in vivo. Among various kinds of phospholipids, dioleoylphosphatidylethanolamine (DOPE) has been reported to be the most suitable surfactant for the formation of honeycomb-patterned PLA films. Interfacial tension between a water droplet and the polymer solution is largely dependent on the chemical structure of the phospholipids. DOPE shows high interfacial tension, resulting in the stabilization of water droplets during solvent evaporation. Dierucoylphosphatidylcholine (DEPC) and dierucoylphosphatidylethanolamine (DEPE), both of which display high interfacial tension, were also found to be suitable biocompatible surfactants.

In recent years, polymer nanoparticles have been investigated with great interest due to their potential applications in the fields of electronics, photonics, and biotechnology. Here, we report the spontaneous formation of polymer nanoparticles from a clear solution containing a nonvolatile poor solvent by slow evaporation of a volatile good solvent. During evaporation of the good solvent, the solution gradually turns turbid. After evaporation, polymer nanoparticles of homogeneous shape and size are dispersed in the poor solvent. Homogeneous nucleation and successive growth of polymer particles takes place during the dynamic nonequilibrium process of solvent evaporation. The size of the particles, ranging from tens of nanometers to micrometer scale, depends on both polymer concentration and the solvent mixing ratio. Because of the physical generality of the particle formation mechanism, this procedure is applicable to a wide variety of polymers with suitable combinations of solvents. Here, we also show unique features, surface structures and surface properties of polymer nanoparticles prepared by this method.

Lipid-coated enzyme (lipase) was prepared by mixing aqueous solutions of enzyme and synthetic dialkyl amphiphiles; it was insoluble in water but soluble in most organic solvents and showed a high activity for the synthesis of di- and tri-glycerides from monoglycerides and aliphatic acids in non-aqueous and homogeneous organic solvents.