AsiaNano 2002

The following sections are included:

• CONTENTS

A new method is introduced to build organic/organic multilayer films composed of cationic poly(allylamine hydrochloride) (PAH) and negatively-charged poly(sodium 4-styrenesulfonate) (PSS) using the spinning process. The adsorption process is governed by both the viscous force induced by fast solvent elimination and the electrostatic interaction between oppositely-charged species. On the other hand, the centrifugal and air shear forces applied by the spinning process enhance significantly the desorption of weakly-bound polyelectrolyte chains and also induce the planarization of the adsorbed polyelectrolyte layer. The surface of the multilayer films prepared with the spinning process is quite homogeneous and smooth. Also, a new approach to create multilayer ultrathin films with well-defined micropatterns in short process time is introduced. To achieve such micropatterns with high line resolution in organic multilayer films, microfluidic channels were combined with the convective self-assembly process employing both hydrogen bonding and electrostatic intermolecular interactions. As a next step, we extended the spin SA to the fabrication of multilayer micropatterns with vertical heterostructure.

Magnetic bacteria synthesize intracellular magnets which are encapsulated by lipid bilayer membranes. Easy aqueous dispersion of bacterial magnetic particles (BMPs) enable development of highly sensitive chemiluminescence enzyme immunoassays by antibodies on BMP surfaces. We have reported a technique for preparing recombinant BMPs on which proteins were displayed by gene-fusion. We further applied such recombinant BMPs to biotechnologically-important issues, including novel bioassay platforms for medicine and environmental management.

Lipid-packaged platinum complexes of [Pt(en)₂][PtX₂(en)₂] (X = Cl, Br, I) are newly synthesized and their morphology and charge transfer (CT) absorption characteristics are compared in organic media. They show remarkably red-shifted CT absorption characteristics, which are ascribed to the significantly promoted exciton delocalization along the chains.

Self-organization of metal nanoparticles, which is observed by mixing Ag nanoparticles and precious metal nanoparticles, is applied to the synthesis of Pd/Ag/Rh trimetallic nanoparticles having a Pd-core/Ag-interlayer/Rh-shell structure. These trimetallic nanoparticles work as a more active catalyst for hydrogenation of olefin than the corresponding monometallic and bimetallic nanoparticles.

Monolayers of a lipophilic C₆₀-derivative (FPTL) mixed in dipalmitoyl-phosphatidyl-choline (DPPC) have been studied by the Langmuir film balance technique and Brewster angle microscopy. Previous X-ray scattering studies showed that the FPTL molecules intercalated into the DPPC monolayers and modified the bending and compression modulus of the host DPPC membranes. Combined study of surface pressure–area isotherms and Brewster angle microscopy measurements clearly established that the liquid-condensed domain structures are strongly influenced by an addition of the fullerene bearing lipid molecules, where it caused smaller liquid-condensed domain structures.

Surface plasmon (SP) excitations have been investigated in the attenuated total reflection (ATR) Kretschmann configuration of prism/metal/Langmuir–Blodgett (LB) films containing dyes. The emission light through the prism was observed using direct irradiation of a laser beam from air to the LB films, i.e., reverse irradiation. The emission intensities depend on the emission angles through the prism, nanostructure of metal and LB films, dye molecules, separation between metal and dye molecules, interactions of dye molecules, etc. The spectra is strongly depended on the emission angles, and the emission light was caused by multiple SP excitations. Nanostructured devices of LB films using SP excitations are described.

We report that tissue-like structure can be formed when cells are cultured on a microporous polymer film (honeycomb film). The honeycomb films were fabricated by applying a moist air to a spread polymer solution containing biodegradable polymers (poly(L-lactic acid) (PLLA) and poly(ε-caprolactone) (PCL)) and an amphiphilic polymer. Hepatocytes were cultured on a self-supporting honeycomb film of PLLA. The hepatocytes formed a single layer of columnar shape cells with a thickness of 20 μm. The tissue formation of hepatocytes was specifically occurred on the honeycomb film of PLLA and not on a flat film of PLLA. Three-dimensional tissue structures were formed, when cells were cultured on both sides of the self-supporting honeycomb film. Double layers of hepatocytes were obtained by the method. Striated tissues such as heart and blood vessel could be reconstructed by utilizing a stretched honeycomb film of PCL.

Multicomponent micropatterned organosilane monolayers were successfully fabricated on Si substrate by stepwise vacuum ultraviolet-ray (VUV) photodecomposition and chemisorption process. The area-specific introduction of different organosilane molecules was confirmed by X-ray photoelectron spectroscopy (XPS). Atomic force microscopic (AFM) observation and lateral force microscopic (LFM) measurement revealed that the line-widths of the micropatterned surface corresponded to those of photomask. Micropatterning of the functional groups influenced the magnitudes of the surface free energy. The patterned surface was also applied for the site-specific polymerization and site-specific adsorption of microparticles.

Carbon nanofibers (CNFs) were coated by surfactants of polyoxyetheylene alkyl ether (AEO₉, AEO₇) and polyvinyl alcohol (PVA 1799), respectively, after being mixed with surfactant aqueous solution and then treated with ultrasonication, high shear and magnetic stirring. The CNF/epoxy composites were prepared by mixing the surfactant coated CNFs with epoxy. Tensile strength, elastic modulus and ultimate strain of the composites were studied. The tensile strength and the ultimate strain of the composites were increased by 20% and 70%, respectively, after the CNFs were coated by surfactants. However, the elastic modulus of the composite will be lowered when the CNFs were treated by too high a concentration of surfactant solution.

Diamond whiskers were formed by etching diamond thin films using metal clusters as a shadow mask, which were deposited on the diamond film before or during etching. The whiskers were as thin as 100 nm and the density was as high as 10¹⁰/cm². The secondary electron emission yield of the diamond whiskers was significantly reduced as compared to the initial diamond film. The decrease in the yield was more significant if the primary electrons were impinged in parallel direction with the whiskers. We suggest that absorption of the secondary electrons in the narrow gap between the whiskers was the reason for the decreased yield.

Cube-shaped CdS nanoparticles have been successfully prepared by a sonochemical method in an oil-in-water microemulsion. The product was characterized by using techniques including X-ray powder diffraction, high-resolution transmission electron microscopy, energy-dispersive X-ray analysis and UV-visible absorption spectroscopy. This microemulsion system in the presence of high-intensity ultrasound irradiation provides special conditions for the nucleation and growth of the CdS nanoparticles.

The electrochemical insertion–deinsertion of lithium into CuO electrode was examined by Cu K-edge X-ray absorption near edge structure (XANES) during the first electrochemical cycle. The XANES spectra in the Li_xCuO (x: lithium content) system reveal that the initial insertion of lithium leads to the reduction of the Cu²⁺ in the pristine CuO to form the reduced nanosized Cu metal. In the successive deinsertion of lithium, the reduced Cu particles changed partially to the phase of Cu₂O.

The spreading behavior of a bolaamphiphilic diacid (1,18-octadecanedicarboxylic acid, ODA) on an aqueous subphase containing lanthanum chloride was investigated. ODA formed a multilayer film on the subphase, and flower- or ring-like nanoarchitectures were observed by an AFM measurement on the transferred one-layer film. It was found that while the above exotic nanostructures were formed in the spreading films at lower concentration of La³⁺ ion, only aggregated circular nanoparticles were observed for those on a higher concentration of La³⁺ ion.

New Mn12 single-molecule nanomagnets [Mn₁₂O₁₂(O₂CCHCl₂)(H₂O)₄]·2CH₂Cl₂·H₂O and [Mn₁₂O₁₂(O₂CCHCl₂)(H₂O)₄]·2CH₃C₆H₅·4H₂O and novel Mn18 complexes [M₁₈O₁₄(O₂CR)₁₈(hmp)₄(hmpH)₂(H₂O)₂] (R = Me, Et) have been synthesized and characterized by single crystal X-ray crystallography and dc- and ac-magnetic susceptibility measurements. Mn12 complexes show characteristic SMM properties, such as temperature-dependent out-of-phase ac-susceptibility. Mn18 does not show relaxation behaviors down to 2.0 K, but reveals magnetic anisotropy in reduced magnetization experiment.

The fluorescence behavior of 3,3'diethyl-thiacarbocyanine iodide in micrometer-sized polystyrene droplets, or "domes" on glass substrates was investigated. The samples were prepared by casting dilute polymer/dye solutions onto the substrates. A dewetting process leads to the formation of small polymer domes with a diameter of 1–100 μm and a height of 100 nm to several μm. Fluorescence microscopy shows that the dye is incorporated into these polymer domes. It was found that the absorption and fluorescence spectra depend on the size of the polymer domes. Larger domes show red-shifted fluorescence spectra.

Self-assembling behavior of both a cardanol-appended glycolipid mixture and the fractionated four components has been examined in aqueous solutions. The cardanyl glucoside mixture differing in the degree of unsaturation in the hydrophobic chain was found to self-assemble in water to form open-ended nanotube structures with 10–15 nm inner diameters. The pure saturated homologue produced twisted helical ribbons through self-assembly, whereas the monoene derivative gave tubular structures. The rational control of helical and tubular morphologies has been achieved by a combinatorial approach through the binary self-assembly of the saturated and monoene derivatives. The flexural rigidity of a single lipid nanotube was first evaluated using optical tweezers manipulation and then compared with that of natural microtubules.

One-dimensional nanochains consisting of Cu nanoparticles and PVA nanofiber were prepared in the presence of a deoxidant NaHSO₃ by electrospinning. Their morphologies and stability were characterized by TEM and UV-vis spectra. The results show that three kinds of nanochains were formed according to the ratio of diameters of the nanoparticles to the nanofiber, i.e., Cu/PVA is equal to, larger, and smaller than 1. The nanochains are stable in air.

Silver nanoclusters have been formed by thermal decomposition of Ag-oleate complex. Transmission electron microscopic (TBM) images of the particles showed two-dimensional assembly of particles with diameter of 10.5 nm. Energy-dispersive X-ray (EDX) spectrum and X-ray diffraction (XRD) peaks of the nanoclusters showed the highly crystalline nature of the silver structures. The decomposition of silver-oleate complex was analyzed by Thermo Gravimetric Analyzer (TGA) and the crystallization process was observed by XRD. The removal of the surfactant surrounding silver nanoclusters was measured by FT-IR and SEM images.

In the aim to prepare thick porphyrin molecular wires, which is visible by atomic force microscopy (AFM), even on the rough surfaces of nanogap electrodes fabricated by electron beam lithography, dendrimer protected porphyrins whose two meso-positions are substituted with ethynyl groups. The porphyrin monomer was reacted with palladium catalyst to make oligomers. Analyses of them with time-of-flight mass spectroscopy (TOF-MS), gel-permeation-chromatography (GPC) revealed that the oligomers were distributed up to 16 mer, whose molecular weight was about 38 000 Daltons.

Tetra-meso-substituted rhodium(III) porphyrins with axial ligand of molecular wire were synthesized for the first time to demonstrate the preparation of self-standing molecule for measuring a single electron conductivity using scanning tunneling microscope technique. The self-standing structure of molecular wire was confirmed by X-ray crystallographic analysis. Cyclic and pulse voltammograms of each compound were measured, and these results indicated that we can freely change the energy level of self-standing molecule and estimate it by using voltammetric measurement.

The manganese-doped ZnS (ZnS:Mn²⁺) nanocrystals were prepared by addition of Na₂S to an Zinc Oleate and Mn(NO₃)₂ solution. It was done using auto-clave method. The aging in auto-clave resulted in Mn²⁺-doped ZnS particle. The emitting band ZnS:Mn²⁺ showed red-shift from that of ZnS and results in the emission band at 500 nm ~ 650 nm (λ_max = 575 nm). ZnS:Mn²⁺ particles dispersed in polymer for production of the green house films. So this film will be used as light wavelength modification materials for the utilization of plant growth acceleration. Luminescence properties of the film were measured by luminescence spectrometer.

Materials such as CdS and CdSe inorganic nanoparticles have photoluminescence. Sodium oleate has been used as effective stabilizers for the synthesis of CdS and CdSe nanoparticles in water by autoclave method. Photoluminescence of CdS and CdSe with particle size of 5–14 nm showed λ_max at 520 nm and 600 nm, respectively, when were excited at 365 nm. These nanoparticles doped into the PVA resulted in the organic/inorganic films (PVA/CdS, CdSe). Photoluminescence, X-ray diffraction and transmission electron microscopy were employed for their characterization.

In this work, we showed that metal salts were easily deposited as aggregates (e.g., ultra-thin planar microcrystals) on the surface of TiO₂-gel films in the absence of ion-exchange sites. In contrast, metal ions were efficiently incorporated into ultrathin TiO₂-gel films, when ion-exchange sites were created using Mg(O-Et)₂ as template. A variety of metal ions, including those of main group, transition, and lanthanide elements were successfully doped into TiO₂ thin films by the current approach. Probable distribution of the ion-exchange site in the film interior was discussed.

ZnO nanotetrapods were synthesized by microwave plasma. The nanotetrapod structures were imaged to be straight with diameters in the range of 10 to 25 nm and lengths up to 160 nm by transmission electron microscopes (TEM). The dark field images and lattice fringes of high resolution TEM show that the crystal orientation or structure of the core is different from that of the legs. The Auger electron peak of Zn shifts more distinctly to lower energy in the legs, which indicates the degree difference of bond ionicity between the core and leg. Cathodoluminescence spectrum of a single ZnO nanotetrapod is characterized by a stronger ultraviolet emission without broad emission bands in its lower energy side. This result further suggests that ZnO nanotetrapods are free from defects.

Mesoporous silica composites filling densely peptide assemblies (Proteosilica) were newly synthesized as transparent films. Spiropyran guest was co-doped in the films and photoisomerization between spiropyran form and merocyanine form was repeated by alternate irradiation of visible and UV lights. Circular dichroism (CD) active spectra were observed only for the spiropyran form in the Proteosilica with hexagonal geometry. However, the CD active behavior was absent for the spiropyran in lamellar Proteosilica. Difference in peptide assembling structures would affect chiral sensitivity of the doped spiropyran guest.

We obtained thin films of the AlPdRe icosahedral quasicrystals by molecular beam epitaxy and post-annealing. The thickness of the films was estimated to be smaller than 100 nm. Any preferred orientation in the X-ray diffraction peaks was not observed in the films.

Luminescent poly(ethylene glycol)-coated polystyrene (PSt) nanometer-sized particles (nanoparticles) containing trivalent europium or terbium ion were prepared by free-radical dispersion copolymerization of styrene, poly(ethylene glycol) (PEG) macromonomer, and the lanthanide complex which was coordinated with 1,10-phenanthroline possessing acryl group. Red and green luminescences with narrow band width were observed from each nanoparticle containing europium and terbium complexes, respectively.

Nanosize SiO₂ particles with narrow size distribution were produced by modified Stober–Fink–Bohn method. Average particle size was determined as 170 nm by SEM image. Organosilica mesoporous molecular sieve (MCM-48) was synthesized. The calcined MCM-48 has pore diameter of 26.8 Å and a surface area of 1024 m²g^-1 by BET (Brunauer–Emmet–Teller) measurement.

Toward an understanding of intermolecular-interaction effects on the third-order nonlinear optical properties of nanostructured molecular aggregates, we investigate the longitudinal second hyperpolarizabilities (γ) of model dimers composed of neutral (C₅H₇) and charged monomers using ab initio molecular orbital methods. It is found that π–π orbital interaction in the stacking direction remarkably affects the γ values of dimers, while the difference in spin configuration hardly causes significant changes in γ for the present models due to weak exchange interactions between monomers.

We fabricated periodic structures of CdS using honeycomb films consisting of an amphiphilic copolymer as a template. The honeycomb film using an amphiphilic copolymer was fabricated on the water surface under highly humid condition and was then transferred onto a solid substrate. The pore size in the honeycomb film was ca. 5 μm. The CdS nanoparticles were synthesized using a gelatin as an inhibitor of rapid nuclear growth and then the gelatin was removed by decomposition using an enzyme. The CdS particles were introduced into pores of the honeycomb film by casting, dipping, and electrochemical deposition. Dipping the honeycomb film into CdS suspension under ultrasonication, periodic deposition of CdS particles in the honeycomb holes was achieved. The CdS-honeycomb film composite was calcinated at 450° C for 30 min in order to remove organic moiety. After calcination, periodic arrangement of porous CdS dots with diameter of 3–5 μm was partially formed. The CdS dots are applicable to photoelectrochemical and optical devices such as a photodiode.

We have studied the construction and electronic characteristics of a series of devices made from gold microgap electrodes, gold nanoparticles and conjugated oligothiophene dithiols. The formations of gold nanoparticle/oligothiophene dithiol composites on gold surface were monitored by quartz crystal microbalance (QCM) using gold electrode coated crystal oscillator. The formation speed was the fastest for terthiophene dithiol followed by hexathiophene and nanothiophene dithiols, the latter two showed almost the same formation speed. The current–voltage (I/V) curves of these devices were measured at various temperatures to show that at high temperature (>200 K) they were almost straight line; at lower temperature they became parabolic, and at 4 K a completely blocked region appeared between -12 to +12 V. We attributed the parabolic I/V curve to a tunneling mechanism and the blocked region to the Coulomb blockade phenomena.

The ZnO nanoparticles were synthesized by using a combination of precipitation and mechanical milling. Basic zinc carbonate precursor was prepared by precipitation process using zinc sulfate as the starting material. Under the mechanochemical effect, parts of the basic zinc carbonate were transformed into ZnO. In the closed system of milling, in order to produce pure ZnO nanoparticle phase, further heat processing was needed. But the ultimate ZnO particles were more uniform and the particle size distribution was narrower. The effects of mechanical milling process on properties of ultimate ZnO particles were also investigated.

Recently a method that utilizes the condensation of micrometer-sized water droplets on evaporating solutions of polymers has been reported for the preparation of porous thin films with fine hexagonal periodicity, honeycomb films. Here we report a method for imprinting a honeycomb pattern on the PDMS (poly(dimethyl siloxane)) elastomer. For the preparation of the honeycomb film, a benzene solution of amphiphilic copolymer was cast at high atmospheric humidity. On the film the PDMS precursor was poured and cured. The cured PDMS with the honeycomb film was peeled from the slide glass. The PDMS was rinsed with the solvent to remove the honeycomb film. The exposed PDMS surface was observed using SEM and AFM. The pattern-imprinted PDMS surface can be used as a template for patterning of materials, which are difficult to produce a honeycomb pattern by the conventional method described above. Here, we show some examples of such honeycomb-originated structures composed of polymers or nanoparticles, which were fabricated using the pattern-imprinted PDMS. The present study shows an example of the secondary uses of the self-organized structures for the cost-saving mi-cro/nanofabrication of various materials.

The cutting and splitting of carbon nanotube bundles were realized with an atomic force microscopy (AFM) in contact mode. The results of manipulating were found depending on the tip–bundle interaction and bundle–substrate interaction. With an optimal force load of AFM tip, the lateral force applied on the nanotube bundle could overcome the adhesive interaction between nanotubes within the bundle, consequently separating individual nanotubes from the bundle. The threshold of the tip force load was found to be ~45 nN in our experiments. This technique provides new possibilities for the controllable manipulation of carbon nanotubes.

Semiconductor CdTe nanoparticles were synthesized by the γ-irradiation of Cd ion complex at room temperature. Cd-olate complex was reacted with aqueous NaHTe solution. The products were investigated by X-ray Powder Diffraction (XRD) and Transmission Electron Microscopy (TEM). The optical properties of CdTe were investigated with UV-vis and photoluminescence (PL) spectra.

The high-temperature and high-pressure liquid (HTPL) crystallization method was proved to be effective to fabricate nanocrystals of quinacridone and its dimethyl derivative. The quinacridone nanocrystals were spherical shape and monodispersed with the average size of around 50 nm, respectively. It was found that quinacridone nanocrystal in different crystal form could be obtained by changing experimental conditions in HTPL method.

The electrochemical behavior of viologen self-assembled monolayer has been investigated with QCM, which has been known as ng order mass detector. The self-assembly process of viologen was monitored using resonant frequency (ΔF) and resonant resistance (R). The QCM measurements indicated a mass adsorption for viologen assembling on the gold surface with a frequency change of about 300, 135 Hz and its surface coverage (Γ) was calculated to be 5.02 × 10^-9 and 1.64 × 10^-9 mol/cm². A reversible redox process was also observed and analyzed with an ionic interaction at the viologen/solution interface using ΔF.

Monolayers of thymine amphiphile containing azobenzene chromophore (Azo-Thy) were prepared on various aqueous oligonucleotide (dA₃₀, d(GA)₁₅, d(GGA)₁₀) subphases. Pressure–area isotherms and reflection absorption spectra of the monolayers on dA₃₀ or d(GA)₁₅ solution showed that the H-aggregate of the azobenzene units was formed at higher surface pressure than 25 mN/m. In contrast, the monolayer on an aqueous d(GGA)₁₀ solution did not form any aggregates of the azobenzene units even at high surface pressure. Base-pair formation between Azo-Thy and template d(GGA)₁₀ could give free volume to the azobenzene units in the monolayer to prevent the aggregation of the azobenzene units at the air–water interface.

We employ the method of phase-modulated KrF excimer pulsed laser interference crystallization to fabricate nanometer-sized crystalline silicon with two-dimensional patterned distribution within the ultra-thin amouphous Si:H single-layer. The local phase transition occurs in ultra-thin a-Si:H film after laser interference crystallization under proper energy density. The results of atomic force microscopy, Raman scattering spectroscopy, cross-section transmission electron microscopy and scanning electron microscopy demonstrate that Si nanocrystallites are formed within the initial a-Si:H single-layer, selectively located in the discal regions with the diameter of 250 nm and patterned with the same 2D periodicity of 2.0 μm as the phase-shifting grating. The results demonstrate that the present method can be used to fabricate patterned nc-Si films for device applications.

The photopatterning process of self-assembled monolayer has been used as template for fabricating biomolecular microstructures. Alkanethiolates formed by the adsorption of 1-octanethiol molecules on a gold substrate were oxidized by the irradiation of deep UV light and then developed with deionized water. The resulting positive patterned substrate was immersed into a dilute ethanolic solution of 11-mercaptoundecanoic acid (11-MUDA). Cytochrome c monolayers were immobilized onto the patterned gold substrate by self-assembly technique and their electrochemical properties were investigated through the measurements of cyclic voltammetry. Also, I–V characteristics of biomolecular multilayers consisting of cytochrome c and green fluorescent protein (GFP) were studied with a scanning tunneling microscope (STM).

A novel procedure to fabricate nanoarchitectures of crystalline titania hollow shells was developed by using assembled latex particles as templates. Latex particles were assembled on the surface of solid substrates and covered with ultrathin titania films by the surface sol–gel process. When the titania-covered latex particle was subjected to oxygen plasma treatment, hollow titania spheres were formed at the original site of particle deposition. Following calcination of the amorphous, titania hollow shells induced their crystallization to titania nanocrystals (anatase).

Correlation between molar fraction and area fraction in micro-phase separated structures formed in binary mixed Langmuir monolayers of arachidic acid (C20) and a per-fluoropolyether amphiphile (PFPE) has been examined. On the water surface, C20 and PFPE separate into fully condensed micro-domains and a largely expanded phase, respectively. The area fraction of the condensed phase domains is estimated by two different ways: one is by analyzing atomic force microscope (AFM) images and the other is calculated from π–A isotherm data assuming complete immiscibility of the film components in the monolayers. Two area fractions are in agreement with each other, and increase exponentially with increase in molar fraction. Our results ensure the complete phase separation of the two film components on the water surface, the monolayer transfer without any structural changes, and the fruitfulness of digital image analysis for the evaluation of two-dimensional organized structures.

The resistance of the Langmuir–Blodgett films of ditetradecyldimethylammonium-Au(dmit)₂ (2C₁₄-Au(dmit)₂) salt has been measured under hydrostatic pressure up to 0.7 GPa. The room-temperature resistance decreases with increasing pressure, reaching a 0.6-times smaller value compared to that at ambient pressure. The film under the pressure shows a clear resistance decrease below 1.4 K on cooling, while that under ambient pressure shows a blunt decrease below 0.85 K and it turns to increase below 0.65 K. These results suggest the existence of the pressure-induced superconducting phase together with the earlier results of the ac magnetic susceptibility measurement.

With the aim of studying single charging phenomena of individual molecules that have clear redox states, a series of ruthenium complexes surrounded by dendrimers were prepared. The structure and electronic characteristics of them were studied by ¹H NMR, MALDI TOF-MS, UV-vis absorption spectra and electrochemical methods. The electrochemical results revealed that the clear redox states were retained even with the surrounding dendrimers, and the molecules can be good candidates for nanometer size charging pools.

We describe a simple and effective approach to the introduction of a functional group into polymer nanofilms on the solid surface using reactive Langmuir–Blodgett films. N-Dodecylacrylamide copolymers containing a terminal amino group in the side chains as a reactive moiety form a stable monolayer on a water surface, and the monolayer was transferred onto a solid support with a transfer ratio of unity. The LB films were characterized by various spectroscopic methods. The reactivity of the terminal amino group incorporated in the LB films was investigated in detail using fluorescein isothiocyanate (FITC) as a fluorescent probe. The chemical reaction between the amino group in the LB films and FITC in the bulk solution was completed within approximately 30 min and the chemical bond formation was confirmed by FT-IR spectroscopy. Furthermore, the ability as a pH sensor was observed with fluorescent microscopy.

The change in the photoluminescence intensity of CdSe nanocrystal/polymer thin films with duration of illumination is investigated. The choice of polymer has an influence on photobrightening and photodarkening. In particular, photodarkening in CdSe nanocrystal/poly(vinyl carbazole) thin film occurs immediately upon illumination, in contrast to the slow changes observed with polystyrene and poly(2-vinylpridine). We discuss the mechanisms of this phenomenon in comparison with interaction between surface of CdSe nanocrystals and polymer side chain.

We report precise analysis of particle position while optically manipulating a particle in solution. Three-dimensional position sensing system, which we developed for measuring femto-Newton force upon a single particle, was used to detect particle position in nanometer resolution. A laser trapping system and a total internal reflection microscope are combined. During manipulation of a microparticle in the vicinity of an interface, the position of the particle behaves as stepwise transition. The spacing of the stable position is coincident with the half wavelength of the trapping laser beam, so that we conclude the surface reflection from the interface causes the stepwise transition. The force measurement is based on a thermodynamic analysis of Brownian motion, and this system can be applied to measure the force onto a single nanoparticle.

Static second hyperpolarizability (γ) of 1,4-phenylendiamine and 4,4'-diaminodiphenylamine in neutral and dicationic states are investigated as model systems of dendritic structure. Expansion of π-conjugation is found to significantly enhance the γ value of the neutral model system. Charged defect in the present system is found to have a remarkable influence on the magnitude and sign of static γ in the direction of π-conjugation.

Light transmission through an opaque nanoscale metallic photonic crystal slabs (MPCS) are investigated. The experimental results show that it is possible to get the extraordinary transmission in visible region even without the presence of holes, which is different from the perforated nanoholes or nanoslits in metallic system. The observed phenomenon can be understood in terms of surface plasmon-enhanced resonant emission of light through a metal structure with a nanoscale corrugation rather than light penetration through tiny holes. It is the periodicity of the interface corrugation that is important for the plasmon as a radiative channel rather than loss. The study suggests that a wide range of photonic applications is possible for such system.

In this research, we report the characterization of the probe and target oligonucleotide hybridization reaction using the evanescent field microscopy. For detection of DNA hybridization assay, a high-density array of sensor probes were prepared by randomly distributing a mixture of particles immobilized with oligonucleotides for DNA chip applications. With the evanescent field excitation and real-time detection method, we suggest that a very sharp discrimination of bulk fluorescence against surface excitation in combination with high excitation intensities can be achieved.

In order to develop a new DNA sequencing method by using chemical force microscopy (CFM), we have investigated the interaction of the hydrogen bonding between surfaces of nucleobase self-assembled monolayers (SAMs) and AFM-tips modified with the nucleobases. The two different adhesion forces, the jump-in force and pull-off force, between the AFM-tip modified with cytosine-SAM and the surfaces of four kinds of nucleobase SAMs were measured in water (20°C) by CFM. The adsorption of poly (C) onto a nucleobase-SAM on a gold electrode of quartz crystal microbalance (QCM) was measured as resonance frequency changes. The relative relation among four bases showed similar tendency in the adhesion force measured by the cytosine AFM-tip and in the adsorption amount of poly (C) on the QCM electrode as well as in the theoretically calculated interaction energies between two nucleobases.

The honeycomb patterned titania films with submicron pores were prepared by a sol–gel reaction. Self-organized 2D arrays of water droplets were formed on surfaces of reaction solution as a template. Polystyrene particles were embedded into the micropores of the honeycomb films by casting dispersion of the particles. The arrangement of aggregated particles was controlled by changing pore sizes.

In order to construct chromophores arrays that precisely controlled their arrangement, monolayers of an azobenzene bearing nucleoamphiphile were prepared on various oligoDNA solutions. Monolayers of the amphiphilic adenine derivative bearing an azobenezene moiety (C₁₂AzoC₅Ade) were prepared on thymidylic acid tetramer (dT4) and octamer (dT8) solutions, and UV-vis reflection absorption spectra of the monolayers were measured to investigate aggregation structures of the azobenzene. The absorption maximum of the monolayer was blue-shifted on the dT4 solution and red-shifted on the dT8 solution. It shows that azobenzene groups in the monolayer have parallel orientation (H aggregate) on the dT4 solution. Though, azobenzene groups have head-to-tail orientation (J aggregates) on the dT8 solution. When monolayers of C₁₂AzoC₅Ade were prepared on the synthesized cyclic oligonucleotides, the absorption spectra were totally different from those of the corresponding linear oligonucleotides.

In recent years, many mammalian cells, especially erythrocytes because of simpleness of their membrane surfaces, were widely studied by atomic force microscopy. In our study, diseased erythrocytes were taken from patients of lung cancer, myelodisplastic syndrome (MDS), and so on. We obtained many clear topographical images of numerous erythrocytes, single erythrocyte, and ultramicrostructure of erythrocyte membrane surfaces from normal persons and patients. By studying the red cells of lung cancer patients, we found that many erythrocytes of lung cancer patient have changed into echinocytes. One erythrocyte has 10–20 short projections, most of which, with a mean width of 589.0 nm and a length of 646.7 nm, are on the edge of cell. The projections in the center of echinocytes are lodged and embedded, but in conventional model of echinocytes, the projections in the center stretch outside cell membrane, so a novel model of erythrocytes was designed in our paper. After observation of microstructure of MDS patient's erythrocyte membrane surface, we found that many apertures with different diameters of tens to hundreds nanometers appeared on the surface of cell membrane. It can be concluded that AFM may be widely applied in clinic pathological inspection.

Fabrication and surface modification of a cell scaffold are very important in tissue engineering. In this study, the effects of pore size and surface wettability on hepatocyte adhesion and morphology was studied, using the porous poly-ε-caprolactone (PCL) film prepared by a simple casting technique. The degree of spreading of hepatocyte was enhanced with the decrease of the pore size (~10 μm). Hepatocyte motility and spreading were restricted on the patterned film having cellular-sized pores (ca. 20 μm). Partial hydrolysis of the film surface enhanced the migration and spheroid formation of the cultured hepatocyte.

We propose a new method that double-stranded DNA molecules can be stretched and immobilized on the clean glass substrate by using a lipid monolayer at the air–water interface. This method is based on the substrate lifting of Langmuir–Blodgett method. We observed fluorescence images of polyion complex films with a scanning near-field optical microscope (SNOM). As a result, straight fluorescent lines aligned parallel to the lifting direction were observed and it was considered that isolated single DNA molecules were extended to align on the substrate. This method is applied to various DNA molecules.

A template polymerization approach is reported to prepare uniform functional sandwiched magnetic composite nanomicrospheres with polymer core, magnetic Fe₃O₄ mezzanine and multicomponent polymer shell. The fine superparamagnetic properties, thermostability and stability in a wide pH range of aqueous solution made the composite mirospheres had the potential applications in biology and medicine.

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.

Two-exciton migration dynamics of a molecular aggregate is performed using the density matrix approach. Exciton–exciton correlation is shown to cause an oscillatory behavior in the one-exciton population dynamics. Such a feature is found to be well explained by the bypass transition from the ground to a one-exciton forbidden state via a two-exciton state.

Single-walled carbon nanotubes (SWNTs), multiwalled carbon nanotubes (MWNTs) and vapor-grown carbon nanofibers (VGCNFs)/epoxy matrix nanocomposites were prepared, respectively. The microstructure of the nanocomposites was observed by SEM and the resistivities of the nanocomposites with different concentration of CNTs/VGCNFs were measured. Based on the experimental results, the dispersion of SWNTs and MWNTs were relatively poor but that of VGCNFs is uniform within the matrix. The resistivitiy of pure epoxy is about 10^10.5 Ω · cm and several orders of magnitude higher than those of SWNT, MWNT and VGCNF/epoxy nanocomposites. The resistivities of the nanocomposites drop with the increase of the CNTs/VGCNFs content in the matrix and the resistivity of VGCNFs/epoxy nanocomposites was much lower than that of CNT/epoxy nanocomposites.

Variable temperature tapping mode atomic force microscopy is exploited to in situ visualize the morphological evolution of N,N'-di(naphthalene-1-yl)-N,N'-diphthalbenzidine (NPB) thin film. The apparent glass transition of the NPB thin film initially occurred at 60°C, proceeded until 95°C, and crystallization from the glassy state quickly appeared at 135°C. The NPB thin film gradually melted and disappeared when the temperature was above 175°C, revealing the underlying layer. These observations are technically helpful and significant to gauge the temperature dependent lifetime and luminance of organic light-emitting diodes.

Nanoscale friction and related tribological phenomena are studied by a numerical simulation. It is found that the kinetic friction is caused by some resonating phonon excitations. The contribution from the surfaces and lubricant to the kinetic friction is clarified.

Monodispersed DAST nanocrystals have almost been successfully fabricated by means of the inverse reprecipitation method. By employing AC electric field, high electric field of above ca. 1.0 kVcm^-1 could be applied to polar DAST nanocrystals dispersed in decahydronaphthalene, so as to avoid electrophoresis of nanocrystals under DC electric field. The response of DAST nanocrystal dispersion to applied AC electric field was analyzed phenomenologically by fitting Langevin function, which provided a large permanent dipole moment of DAST nanocrystal. In addition, we have succeeded in in situ observation of AC electric-field-induced orientational motion of DAST crystals by using an optical microscope. The present DAST nanocrystal dispersion system will be expected as an optical device like display monitor.

Colloidal ZnO nanocrystals with strong green luminescence were prepared. When ZnO nanocrystals were modified with different organic ligands, the emission quenching was measured and used to study the interaction between ZnO nanocrystal and organic ligands. Efficiency of emission quenching relates to the chemical structures of the ligands, and metal-thiolate bond was formed between nanocrystals and thiol ligands. The relative strength of the binding and the surface concentration of the adsorbed species could be determined using this method.