Search

We successfully synthesized the photofunctionalized octacalcium phosphate (OCP) with layered structures and high biosafety. Specifically, two systems of europium(III) ion (Eu3+)-doped OCP particles...

Green-emitting phosphorus-functionalized mesoporous silica (PMPS) nanospheres were fabricated by modifying their surfaces with (8-hydroxyquinoline) zinc (Znq2). A simulated body fluid soaking test and subsequent gas-adsorption measurements revealed that Znq2-modification could dramatically suppress the biodegradation of the nanospheres. This study establishes Znq2 as a novel and potential surface modifier of mesoporous silicas and demonstrates that effective surface design of the hosts will allow the exploitation of potential functionalities of the modifier.

We successfully prepared hybrid nanoparticles (NPs) with photofunctional interfaces between the citric acid (Cit) molecules and europium(III) ion (Eu3+)-doped hydroxyapatite (HA) (Eu:HA) to provide...

The transparent mesoporous silica (MPS) films prepared by a supramolecular templating method was immersed in simulated body fluid (SBF), and subsequently was sterilized to evaluate the film structural stability. With immersing in SBF, the calcium and phosphate ion adsorption on the film surfaces was promoted and the mesopore structures underwent the expansion, collapse and reconstruction processes for the SBF immersion time of 6 h. The MPS films immersed in SBF for 3 h exhibited the mesostructural stability with the sterilization processes. We also investigated the Fgn adsorption states on the sterilized MPS films, which were clearly changed with the immersion time in SBF because of the different adsorption states of calcium and phosphate ions at the mesopores. Furthermore, the proliferation and differentiation behaviors of the osteoblast-like cells on the sterilized MPS films were investigated to evaluate the cell culture ability. The osteoblast–like cells cultured on the sterilized MPS films had the fibrous morphologies while maintaining the high adhesion density and were promoted to be the bone tissue formation for 14 days, indicating the preferential film environment for the cells. Therefore, it was suggested that the MPS films of this study were useful for the cell culture substrate based on their high transparency, stability against sterilization treatment, and preferential cytocompatibility.

Phosphonate-containing mesoporous silica (PMPS) spheres were successfully synthesized using diethyl(2-bromoethyl)phosphonate and non-ionic and cationic surfactants. The spherical PMPS particles with the mesopores were effectively formed under the basic condition through the hydrolysis and condensation reactions of tetraethoxysilane, even though the BET surface area of the particles decreased with increasing the added phosphonate amount. The hollow structures with the mesopores were obtained in the preferential amount of the phosphonate.

The effect of the phosphoric acid addition into the mesoporous silica (MPS) films on the water molecular states was investigated using the infrared spectral separation techniques. When the larger amount of the phosphoric acid was introduced into the MPS films, the surface wettability was changed to hydrophilicity. The interactions between the PO43− and silicate ions would occur to form the phosphoric acid-interacted MPS films, and the surface silanol groups were effectively interacted with the water molecules, indicating the importance of the incorporated phosphoric ions.

We synthesized hydroxyapatite nanocrystals under the existence of tris(2,2,6,6-tetramethyl-3,5-heptanedionato)europium(III) (EuTH) complex to form inorganic/organic hybrid nanocrystal (EHA). Then, the folic acid derivative (folate N-hydroxysuccinimidyl ester (FA-NHS)) as the targeting ligand for the HeLa cancer cells was immobilized on the EHA by the mediation of both 3-aminopropyltriethoxysilane and methyltriethoxysilane molecules. Here, we investigated the photofunctions based on the interfacial interactions between the FA-NHS and EHA nanohybrids for preparing the novel bioimaging nanomaterials. As a result, the photofunctions could be changed by the FA-NHS molecular occupancy on the EHA. When the molecular occupancy ratio to the EHA surfaces is at around 3–5%, the intense luminescence from the f–f transition of the Eu3+ ions as well as the charge transfer between the EuTH–FA-NHS was observed to exhibit higher quantum efficiency. Moreover, effective dispersibility in phosphate-buffered saline was confir...

Addition of poly (oxyethylene)cholesteryl ether in the synthesis promoted the formation of the hydroxyapatite nanoparticles (HAp NPs) with the elliptical morphologies. The adsorption mechanism, interfacial interactions and conformation of the adsorbed fibrinogen (Fgn) on the HAp NP films were investigated. The Fgn adsorption behavior demonstrated the higher affinity of Fgn with the HAp NP films. At the lower temperature at 22 °C, Fgn was preferentially adsorbed on the gold though hydrophobic interactions with the larger Fgn adsorption amount. At the higher temperature at 37 °C or at the higher phosphate ion concentrations caused the structural changes of the adsorbed Fgn. Moreover, the temperature increment in PBS increased the Fgn adsorption amount with the rearrangement into the end-on orientation of the Fgn. Accordingly, HAp induced the electrostatic force and hydrogen bonding to be the stable Fgn-HAp NP film, minimizing the interactions among the water molecules. The HAp NP films with the preferentially elliptical crystalline shapes induced the Fgn steric conformation structures, and the secondary structural changes of the adsorbed Fgn by the increment of temperature were also supported by the Fourier transform infrared spectroscopy (FTIR) deconvolution results.

We have synthesized novel inorganic–organic hybrid systems based on the interactions between calcium phosphate (CP) and tris(2,2,6,6-tetramethyl-3,5-heptanedionato)europium (III) (EuTH) complex to clarify the states of the EuTH molecules. We achieved the nucleation and crystal growth of electronically localized of EuTH molecules using two different synthetic processes (based on the timing of the addition EuTH before and after the CP nucleation stage). The coordination environment of the Eu3+ ion inside/on the hybrids was clearly changed, having the higher spatial symmetry states in the hybrid. The aspect ratios of the hybrid crystallites were 2.5–6.0, suggesting that the EuTH molecules selectively interacted with the a–plane of the CP nuclei to induce preferential crystal growth along with the uncovered c–plane. The segregated EuTH molecules on CP surfaces suppressed Ca2+ dissolution from the hybrids in phosphate buffer saline. In the excitation spectra of the hybrids, the 7F0 → 5L6 transition appeared as a result of the interaction between the EuTH and phosphate ions, suggesting that the phosphate ions affected the coordination environment. In the luminescence spectra of the hybrids, the luminescence intensity ratio of the magnetic dipole transition (5D0 → 7F1) to electric dipole transition (5D0 → 7F2) were higher than those of EuTH and the other Eu3+-doped inorganic systems. Thus, the higher spatial symmetry states of the Eu3+ ion in the hybrids resulted in greater luminescence intensities and quantum efficiencies, which would be affected by the phosphorus anti-quenching. In the future, CP hybrids with various organic complexes will be prepared, and these could be applied in the biomedical fields such as in bio-imaging and drug delivery systems.

Transparent phosphorus-containing MPS (PMPS) films were synthesized by the introduction and reaction of phosphoric acid into the silica framework during the sol-gel reaction. We then investigated the hydration layer structures formed on the PMPS films and achieved the selective adsorption of fibronectin (Fn). In particular, the surface analyses indicated that the P atom was distributed at the outermost surfaces of the PMPS films. The PMPS films exhibited a high transparency (e.g., averaged transmittance value in the visible light region: 79%), and the haze value (0.14%) decreased with the increasing P/Si molar concentration. Solid-state 29Si-NMR and Fourier transform infrared spectroscopy (FT-IR) spectra indicated the formation of Si-O-P bonds, suggesting that the condensation reaction between the Si-O- and P-O- groups effectively occurs in the silica framework. The larger amount of P-O- and P[double bond, length as m-dash]O groups at the Si-O-P bonding site on the films affects the water molecular adsorption states (i.e., formation of the hydration layer), which was supported by the Brunauer-Emmett-Teller (BET) surface areas of N2 and water vapor, leading to enhancement of the hydrogen bondability of the PMPS films with the increased formation of Si-O-P bonds. The deconvolution results of the FT-IR spectra demonstrated that the ratio of free water to bonding water increased significantly with an increase in the formation of Si-O-P bonding, and the resulting O-H stretching vibration in the hydration layer became more asymmetric. It is suggested that the water molecules are irregularly hydrogen-bonded with the different functional groups of Si-O-, P-O- and P[double bond, length as m-dash]O. In the immersion experiment of the PMPS films in phosphate buffer, the resultant P/Si molar concentration of the PMPS film decreased upon increasing the immersion time and the mesostructures were preserved. The amount of Fn adsorption significantly increased as the O-H stretching vibration of the water molecules became more asymmetric, whereas the adsorption of fibrinogen was completely suppressed by the films. Therefore, we found that the addition of phosphoric acid in the MPS film synthesis significantly affects the hydration layer structures on the film surfaces to provide the possibility of selective protein adsorption.

We synthesized nanostructured mesoporous silica (MS)/hydroxyapatite (HA) hybrid particles in the presence of amphiphilic poly(ethylene oxide)–poly(propylene oxide)–poly(ethylene oxide) (PEO20PPO70PEO20) triblock copolymer (P123). The particles exhibited slit-shaped mesostructures and underwent hybridization reaction between the MS and HA phases containing P123. Furthermore, the aggregated form of the particles exhibited dispersion stability in water in the monodispersed state (average particle size: 145 nm and coefficient of variation: 4.3% in the case of the maximum added amount of P123). Then, the structures of the hydration layer and the adsorbed protein on the particles were investigated to understand the effect of the hydration layer structures on the protein secondary structures. The ratio of the bonding water (intermediate and nonfreezing water) to free water increased upon hybridization, and it decreased with increasing P123 concentration. Upon hybridization, the component ratio of the asymmetric O–H stretching vibration between free water molecules decreased, and that of the symmetric O–H stretching vibration of intermediate water molecules increased. With increasing P123 concentration, the asymmetric O–H stretching vibration between free water molecules increased and the symmetric O–H stretching vibration of intermediate water molecules decreased. It was found that the protein native state component ratios of α-helix and β-sheet increased with increasing symmetric O–H stretching vibration between intermediate water molecules, and they decreased with decreasing asymmetric O–H stretching vibration between free water molecules. Moreover, the cytotoxicity against osteoblasts (MC3T3-E1) was evaluated and the hybrid particles exhibited a high cell density, indicating their bioactivity. On the hybrid particles interacting with P123, the cells were three-dimensionally assembled and uniaxially grown with the culture. Therefore, this is the first successful report of the synthesis of nanostructured MS/HA hybrid particles interacting with P123, and the controlled hydration layer structures on the particle surfaces were found to contribute to the protein secondary structures, promoting cytocompatibility.

The nanostructured hydroxyapatite (HAp) formation in fish scales were investigated. Calcium and phosphate ions were effectively accumulated in the scales by the immersion processes. The HAp nanoparticles arranged in one direction in the internal fibrillary plate layers were observed, revealing the crystal growth along with the collagen fibers to resultantly form the porous structures. Thus, the arrangement of collagen fibers inside the scales effectively form the HAp nanostructures.

We demonstrate a new class of nanocoating materials for biocompatible electrode based on poly (pyrrole-co-formyl pyrrole) (P(Py-co-Fpy)) multilayered with polystyrene sulfonate (PSS) using layer by layer (LBL) self-assembly technique. By modulating the number layer of deposition, the unique surface properties of P(Py-co-Fpy) are evaluated for bioaffinity. Atomic force microscopy (AFM) demonstrates the controllable morphology of the degree fibril network structure of P(Py-co-Fpy)/PSS surface. The direct adsorption of bovine serum albumin (BSA) onto the top surface of P(Py-co-Fpy)/PSS film by AFM analysis reveals the forming of BSA multilayer at high degree of fibril structure P(Py-co-Fpy). In addition, the adsorbed fibrinogen (Fgn) reveals the reversible conformation change on surface of P(Py-co-Fpy)/PSS. The effect of P(Py-co-Fpy)/PSS morphology on primary mouse embryonic fibroblasts (MEF) is investigated. Cell morphology and proliferation on P(Py-co-Fpy)/PSS LBL film at different number of layer deposition are evaluated, demonstrating that P(Py-co-Fpy)/PSS LBL nanocoating surface is non-cytotoxic as morphology-dependent.

Competitive incorporation of Eu3+ and Na+ ions into citric acid-passivated hydroxyapatite (Cit/HA) particles was investigated for improving the photoluminescence internal quantum yield (ηint). As a result, Eu3+/Na+-co-doped Cit/HA (Cit/HA:Eu/Na) particles were successfully synthesized to control the Eu3+ states inside/outside the HA structure. The optimum Na+ concentration would suppress the surface deactivation of the Cit/HA:Eu/Na particles, leading to the higher ηint value.

The molecular aggregation states of tris(8-hydroxyquinoline)aluminum(III) (Alq) adsorbed in the transparent mesoporous silica (MPS) films with the different pore sizes (3.0 and 5.4 nm) were successfully clarified. The Alq molecules were easily incorporated into the films from the solution without the segregation on the surfaces. The adsorbed amount of Alq was controlled by changing the added amount in the initial solution to resultantly give the transparent and yellow-color films. The photoluminescence spectra significantly revealed that the state of Alq molecules in the mesopore varied depending on the adsorbed amount of Alq as well as the pore size, suggesting the characteristic mobility of the adsorbed Alq molecules in the mesopores as compared with that at the bulk or solution state. Therefore, the guest-guest interactions between Alq molecules as well as the host-guest interactions between Alq and mesopore were elucidated. This finding by the use of the mesoporous film hosts will be utilized for including luminescence species and be applicable for optical devices.

The development of a calcium phosphate (CP) coating technique on tissue culture poly(styrene) (TCPS) is important in biomedical fields. In this study, the CP hybridized with l-α-phosphatidylcholine phospholipid vesicle (PV) was formed on TCPS as the film state for suggesting the unique CP/PV hybrid films. The film formation was conducted by the following two different processes: (i) the CP deposited on PV was prepared in a simulated body fluid (SBF) and subsequently casted on TCPS to form the films, and (ii) the CP was precipitated in SBF on the pre-prepared PV films on TCPS. These films were denoted as “CP/PV-Bef” and “CP/PV-Aft” films. The stability of the CP/PV hybrid films against the sterilization processes (ethanol, UV/ozone, and autoclave treatments) and subsequent immersion process in a phosphate buffer saline (PBS) was also demonstrated. As a result, the CP/PV hybrid films were successfully coated on TCPS through the mediation by PV with preserving the vesicle structure. The morphologies and phys...

A simple rubbing treatment was used to mechanochemically modify the surface of polyacrylonitrile-based carbon fibers and its effect on their surface structure and functional groups was studied using several surface characterization techniques. To control the mechanochemical effect, the shear forces accompanying rubbing were kept constant. Scanning electron microscopy tests and the peak positions and widths of the main Raman spectroscopy bands indicated that there were no morphological changes to the carbon fibers following rubbing. In contrast, X-ray photoelectron spectroscopy showed an increase in oxygen-containing functional groups; in addition to hydroxyl species, the main groups introduced were alkoxide, carbonyl, and carboxyl groups. The ratio of carboxyl groups on the carbon fiber surface increased with the shear force magnitude, indicating carbon surface oxidation. The difference between the Raman and X-ray photoelectron spectroscopy results indicates that the modification was confined to the first few atomic layers; therefore, this rubbing method is capable of producing efficient mechanochemical surface modification of carbon fibers. This technique is simple, is relatively inexpensive, and is applicable to carbon fiber-reinforced plastic processing techniques.

The preparation of terbium(III) (Tb3+)-doped mesoporous silica (Tb:MPS) particles and subsequent hybrid formation with calcium phosphate (CP) were proposed in this study. The surfactant/Tb:MPS particles with an initial doping concentration of Tb3+ ions to (Si + Tb) of 2 mol% were synthesized by a sol–gel reaction based on the cooperative organization of tetraethoxysilane, terbium(III) chloride and cetyltrimethylammonium bromide. Subsequently, the Tb:MPS particles were hybridized with CP through precipitation to form CP/Tb:MPS, where the formation was demonstrated by XRF and EDS analyses. The Tb:MPS showed a mesoporous structure which is typically seen in silica-surfactant mesostructured materials and the mesopores were preserved after precipitating the CP with crystalline phases. PL spectra were measured before and after the precipitation and some spectral changes were recognized. The PL spectral shapes due to the transitions of Tb3+ ions indicated that the Tb3+ ions were located inside the silica framework to interact with the siliceous O atoms. After the CP precipitation, the hybrid particles demonstrated higher quantum efficiency as well as longer PL life time, indicating the improved PL properties based on the CP–Tb3+-silica hybrid states. The interfacial manipulation of the present CP–Tb3+-silica hybrid allowed for unique material design in terms of its morphology and properties. This finding will be utilized for the encapsulation techniques for porous silica including with lanthanide ions and can be applicable for optical devices.

There has been an increasing demand for the development of cell-labeling nanomaterials that safely label and visualize a specific type of cells for diagnosis and inspection in vivo and in vitro. In order to design such cell-labeling nanomaterials, the properties of efficient visible light luminescence and effective interactions with cells have to be realized using a biocompatible nanomaterial. From this viewpoint, we summarize and overview the current situation on cell-labeling technologies. Among various functional nanomaterials, we focus on hydroxyapatite nanoparticles and their photofunctionalization based on the properly designed inorganic-organic hybrid structure such as hydroxyapatite/ organic europium (III) complex. Also, the immobilization technique of a specific binding molecule to the solid surface is introduced to demonstrate the selective uptake into cancer cells. Moreover, an example of the growth inhibitory drug molecules for cancer cells are described, focusing on the cytostatic inhibition of citric acid and the potential use of hydroxyapatite/citric acid hybrids. Finally, we mention our future perspectives on the theranostic nanoparticles with fluorescence and therapeutic properties that are achieved through the hydroxyapatite-organic hybrid interfacial interactions.

Transparent hydroxyapatite/citric acid (Cit/HA) particulate film formation and the stability in biological solution were investigated. Negatively charged Cit/HA nanoparticles were synthesized, and the particulate films were prepared by a spin-coat method through water or ethanol dispersion. As a result, the crack-free and transparent Cit/HA films were prepared from water dispersion, which exhibited the better optical properties as compared with the films prepared from ethanol dispersion. The Cit/HA films exhibited higher optical transmittance with increasing the hybridized Cit amount, and the highest transmittance in the visible light region exceeded 80%. Moreover, the calcined film had long-term stability in phosphate-buffered saline while maintaining high transparency, which is expected to be used as a candidate coating film for cell culture substrates.

Europium (III) (Eu 3 + )-doped hydroxyapatite (HAp) nanocrystals were synthesized in the presence of a cetyltrimethylammonium bromide (CTAB) to investigate the states of Eu 3 + ions in the structure. The HAp structure was preserved with the doping as well as the CTAB existence, and the carbonate ions were included in the structure. The uniform shapes and mono-dispersion of the nanocrystals were observed by adding CTAB. The transitions of 5 D 0 – 7 F 1 and 5 D 0 – 7 F 2 in the photoluminescence spectra indicated the presence of the Eu 3 + in an environment of a low symmetry before the calcination. The Eu 3 + was effectively positioned in the Ca sites in the HAp structure. The CTAB addition would prevent the Eu 3 + ions from aggregating each other, inducing the effective substitution and resultantly showing the efficient luminescence. Therefore, the interactions between the Eu 3 + ions and HAp structure were successfully enhanced in the presence of CTAB.

Calcium phosphate (CP) nanostructure formation using a phospholipid vesicle (PV) template was investigated in a simulated body fluid. The CP nanoshells surrounding a PV/water core (diameter: 194 nm) were successfully prepared to show the hybrid nanostructures. The lyophilized cast films of the nanohybrids exhibited the CP/PV arrangements at nanometer scales as well as osteoblast-like cell adhesion/proliferation, suggesting cytocompatible nanohybrid structures.

To clarify hydroxyapatite (HAp) nanocrystal formation based on the interfacial interactions with organic molecules is important for controlling the dispersion states/shapes of HAp and understanding the biomineralization mechanism. In this study, the effects of cetyltrimethylammonium bromide (CTAB) micelles on the HAp nanocrystal formation process were investigated through both the morphosynthesis technique and the molecular orbital calculations. The HAp nanocrystals synthesized in the presence of CTAB exhibited a controlled rod-like shape and subsequently grew up by a thermal treatment to be larger-sized nanocrystals at a well-dispersed state. It was also found that the CTAB micelles strained and disordered at the higher temperature effectively induced heterogeneous nucleation to initiate the nucleation/growth processes. In contrast, HAp nanocrystals synthesized without CTAB exhibited irregular-shaped and aggregated nanocrystals, which are due to dominantly occurring homogeneous nucleation. According to t...

Transparent phosphorous-containing mesoporous silica films were successfully synthesized by two different processes using the phosphoric acid addition before and after the sol–gel based mesopore formation. In the X-ray diffraction patterns, the films prepared by the addition before the formation exhibited highly-ordered pore channels with a hexagonal structure parallel to a substrate surface, while those after the formation have the larger pores with worm-like structures. Therefore, the highly- and randomly-ordered nanostructures were prepared by the phosphoric acid additive processes before and after the mesopore formation, suggesting the doping inside the silica frameworks and the composite outside the silica mesopores, respectively.

Nanocrystalline zinc (Zn)-substituted hydroxyapatite (HAp) films were prepared and electrically-plated on a titanium-coated silicone to investigate the biological properties. The hydroxyapatite nanocrystals with the different initial molar (Zn + Ca)/P ratios (1.67 and 2.00) and Zn ion concentrations were synthesized and subsequently coated by an electrophoretic deposition method to successfully form homogenous thin films. The nanocrystalline films provided bioactive properties based on the fibroblast ingrowth as well as the reduction in the number of viable Escherichia coli. Therefore, the optimized cytocompatible and antibacterial properties of the films by the effective Zn ion substituted in the HAp will be useful as a silicone surface modification technique.

The effective segregation of chitosan (Chi) molecules in a silica-surfactant nanostructure formation process was investigated to find unique self-assembled nanostructures of Chi. The formation process induced the well-defined segregation nanofiber networks to exhibit osteoblast-like cell adhesion and spreading, suggesting the unique Chi segregation nanostructures cytocompatibility.

Hydroxyapatite (Ca10(PO4)3(OH)2) (HAp) is crystallographically and chemically similar to the human hard tissues and has been widely researched. The naturally formed HAp has some impurities of some ions, which provides the biocompatibility as well as the nanosized morphologies in the tissues. In this study, the morphosynthesis of zinc-substituted stoichiometric and carbonate hydroxyapatite (Zn:HAp and Zn:CAp) nanoparticles was investigated from the reagents of CaCl2, ZnCl2, and K2HPO4. The initial (Ca + Zn)/P ratios of 1.67 and 2.00 were adjusted by the initial ZnCl2amount at the Zn/(Ca + Zn) concentration of 0.0−10 mol%. The crystalline sizes of the nanoparticles decreased with increasing the Zn ion amount, suggesting that the Zn substitution significantly suppressed the crystal growth. TEM images of the nanoparticles indicated that all the crystalline sizes are less than 100 nm and the needle-like shapes were significantly changed to spherical shapes with increasing the Zn ion substitution to resultantly exhibit the higher surface areas as well as the nanoparticle aggregation states. Furthermore, all the nanoparticle films electrically plated on a silicone substrate give no cytotoxicity, and the Zn:CAp nanoparticle films significantly provided the bioactive properties for fibroblast ingrowth, suggesting the effect of Zn and carbonate ions on the cytocompatibility.

Waste bagasse of Agave tequilana-Weber fibers treated with sodium hydroxide was used to elaborate hydrogel films. The bagasse was offered in an alternative use for the preparation of hydrogel films by phase inversion method without crosslinking and further purification of cellulose. The effect on the properties of the obtained films was studied when the chemical treatment of the agave fibers was changed. It was found that the resultant hydrogels showed increment in tensile from 40 N/mm(2) to 56 N/mm(2) with the increase of sodium hypochlorite concentration from 1 to 10 vol.%, respectively. With regard to biocompatibility properties of the hydrogel films, platelet adhesion, clotting time and protein adsorption were investigated. Analysis of the morphology of adherent NIH3T3 fibroblast indicated that the projected cell area, aspect ratio and long axis gradually increased with the increment of sodium hypochlorite content in the agave treatment. It was presented that the chemical treatment affects cell adhesion and morphology and lignin content remains in the brown fibers.

Poly(pyrrole-co-formylpyrrole), P(Py-co-FPy) was prepared on poly(4-styrenesulfonate acid) (PSS) using layer-by-layer (LBL) self-assembly process in the presence of trifluoroacetic acid (TFA) through straightforward chemical polymerization. The P(Py-co-FPy) and PSS multilayer contained homogeneous particulate surfaces with a hierarchical porous structure, depending on the number of layers and the PSS concentration. The layer cycles gave rise to increased electrical conductivity from 2.8 × 10−4 S/cm at 2 layers to 3.2 × 10−3 S/cm at 10 layers, implying the benefit of the doping effect of the sulfonic group on the improvement of electrical conductivity for multilayer films. The electrostatic interaction between the P(Py-co-FPy) and the PSS layer was confirmed from UV–visible spectra. It is enhanced by the number of layers and PSS concentration. Cyclic voltammetry and electrochemical impedance measurements showed that the electrochemical capacitance of those multilayer films is influenced by the increase of the number of layers and the PSS concentration, suggesting that the multilayer film morphology affects the electrochemical behavior.

Luminescent titania-fluorescein (FS) hybrid nanoparticles (NPs) were successfully synthesized by a sol-gel reaction of titanium alkoxide in the presence of octadecylamine using a fluidic reactor with a Y-type channel. The molar ratio of FS/Ti ratio was varied in the range from 1/1000 to 1/100 in order to obtain the hybrid NPs with the different luminescent behavior. The shape of the NPs is spherical and their sizes are 400 nm which is almost the same irrespective of the FS content, suggesting the different FS molecular states in one NP. We also demonstrated that the hybrid NPs exhibited a characteristic luminescence; the NPs with the higher and lower FS contents exhibited an enhanced luminescence in PBS and air, respectively, indicating that the FS states responded to the molecular environment. Through cytocompatible experiments using the NPs, it turned out that they had a high compatibility for fibroblasts. Therefore, the preparation of a series of the luminescent NPs with a tunable luminescence property was achieved. The results will lead to a guideline to determine a proper combination between material composition and an environment where they are used, being useful for biomedical applications.

Biohydrogel interpenetrated films of wooden pulp cellulose and hydroxyethyl cellulose (HEC) were prepared, and their biomedical properties were investigated. Our purpose was to obtain new material combining the nontoxicity and biocompatibility in wooden pulp cellulose films by interpenetration of HEC. It was found that the increment of HEC content affects the mechanical properties of the hydrogel from 10 to 50 wt % content of HEC. In vitro biocompatibility tests showed that protein adsorption, clotting time, and platelet adhesion were affected with the increment of HEC. All of the obtained hydrogels showed better cytocompatibility than the reference on a tissue culture grade polystyrene dish. However, HEC content seemed to decrease fibroblast cell densities due to its effect on the film properties, showing different pulp aggregation. In conclusion, the cell densities on hydrogel were significantly changed depending upon the HEC interpenetration.

Composites between carbon fibers (CFs) and heterogeneous materials have been widely studied and their fabrication techniques have been developed. However, their hydrophobic surfaces make it difficult to disperse CFs into hydrophilic resins, which results in weak junctions with ceramics. To develop high-strength composite fibers, it is important to design interfacial chemical bonds. Thus, surface-modification techniques of CFs have recently become the main focus and their interfaces have been characterized by various analytical methods. In this Minireview, various techniques that modify the CF surface by coating with inorganic polymers (metal oxide compounds) are highlighted, and the applications of novel nanocomposite fibers are also described. Furthermore, interfacial bonds between CFs and polymer resins are reviewed and discussed in terms of CF-reinforced plastics and their future prospects.

Agave fibers were used to elaborate a transparent and flexible cellulose hydrogel films used as scaffold for tissue regeneration and tested by in vitro assays with NIH 3T3 fibroblast cells. Using dimethylacetamide/lithium chloride (DMAc/LiCl) system was possible to obtain cellulose solutions and hydrogel films were prepared by phase inverse method without cross-linker. The concentration of LiCl in the DMAc solution was varied from 4 to 12 wt% in the phase inversion process and then the cytotoxicity was tested for 14 days on the cultivation. The resultant hydrogel films showed better cytocompatibility than the PS dish used as control. The cell growing images showed that the hydrogel films with lower LiCl apparently contained ordered and aggregated fiber orientation. This comparison suggested that the segmental microstructure in the hydrogel films influenced fibroblast cells spreading. In addition, the agave hydrogel films displayed good stability without biodegradiation through the cell cultivation.

The methylene blue (MB) adsorption states on the titania nanoparticles (NPs) prepared by two surfactant removal processes were investigated to demonstrate the singlet oxygen generation efficiency. The NPs with the BET surface areas of 250–350 m2/g exhibited the spherical particle sizes of 100–150 nm, indicating the nanoporous structures. The MB molecular states adsorbed on the NPs prepared by solvent extraction method (WT) were attributed to both the monomer and dimer states, whereas those on the NPs prepared by the baking at 250 °C (BT) were dominantly attributed to the monomer state, indicating the adsorbed states would be affected by the surface functional groups. The singlet oxygen generation efficiency from the MB adsorbed on the BT NPs were higher than that on the WT NPs, and those of the NPs were higher as compared with that the MB alone. Therefore, the generation efficiency would be controlled by the titania surface condition.

Immobilization of 2,2′-bipyridine-5,5′-dicarboxylic acid (Bpdc) into layered octacalcium phosphate was investigated in the hydrolysis process of α-tricalcium phosphate. 100 interlayer distance altered from 1.9 to 2.5–2.7 nm by the immobilization, suggesting the novel inorganic/organic nanohybrids. The nanohybrids exhibited the blue-shifted photoluminescence peaks with the higher internal quantum efficiency as compared with the case in the Bpdc alone.

Agave fibers were used to elaborate transparent and flexible cellulose hydrogel films used as a scaffold for tissue regeneration and tested by in vitro assays with NIH 3T3 fibroblast cells. Using a dimethylacetamide/lithium chloride (DMAc/LiCl) system made it possible to obtain cellulose solutions, and hydrogel films were prepared by phase inverse method without cross-linker. The concentration of LiCl in the DMAc solution was varied from 4 to 12 wt %. The resultant hydrogel films showed water contents in the range of 239–323% and enough film strength from 50 to 66 N/mm2, when the LiCl was changed from 4 to 12 wt % concentrations, respectively. The prepared agave cellulose films showed better cytocompatibility than the polystyrene dish used as control. Atomic force microscopy images showed that the hydrogel films with lower LiCl apparently contained ordered and aggregated fiber orientation. This comparison suggested that the segmental microstructure in the hydrogel films influenced fibroblast cells spreading.

Polyaniline–cellulose acetate hollow fibers prepared from cellulose acetate (CA) solution of aniline (ANI) were founded to show dual layers structure, when wet technique was applied for using syringe injection of the solution to acidic water for ANI polymerization. In this technique, the polymerization of ANI occurred simultaneously by the monomer injection in coagulated CA fibers. Then, the PANI–CA composite fibers were obtained. The formation of the PANI–CA composite fiber was dependent upon HCl concentration and initiator of ammonium persulfate. Especially, when the coagulation time was 1 min, the obtained PANI–CA fibers showed hollowed dual-layer structure having outer layer of PANI and inner layer of CA. Evidence was presented that the dual structure fiber had 40 μm outer layer and 60 μm inner porous layer in their thicknesses. Cyclic voltammograms of the PANI–CA fiber were indicated that the outer layer was composed of PANI layer showing electrochemical properties with electrical capacity of about 0.003 C.

Mechanochemically activated iron oxide formation on α-iron (Fe) microparticles for the efficient reaction with methane (CH4) was investigated using a simple milling process to successfully clarify ...

The effect of ultrasound (US) on the shear viscosity of water-soluble polymers, polyvinyl alcohol, polyethylene glycol and polyacrylic acid, was studied in aqueous solutions with US exposure of 23, 43, 96 and 141 kHz for an 8.5–9 W US. The US exposure significantly decreased the shear viscosity of the solutions in this order: 43>23>96>141 kHz. When US exposure was stopped, the shear viscosities of the aqueous polymer solutions reverted to their original values. US stimulation during the decrease in viscosity was supported by the ultrasonic power transmitted through the aqueous polymer solution. In addition, Fourier-transform infrared spectra obtained during US exposure showed that hydrogen bonds in the aqueous polymer solution could be broken, especially at 43 kHz. We concluded that US exposure influenced hydrogen-bond interactions between the OH groups of the polymer and water molecules in the aqueous medium. This finding was supported by US absorption of the aqueous polymer solution in the transmittance model, which shows the US absorptivity, ɛUS, for each polymer system. The effect of US on the shear viscosity of water-soluble polymer solutions was studied. The 43 kHz US significantly decreased the shear viscosity of the solutions. FT-IR spectra obtained during the US exposure showed that hydrogen bonds in the aqueous polymer solution could be broken. US absorption model was proposed to explain US absorption and the breakage in the hydrogen bonds. US effect influenced the condition of water solvation to the water-soluble polymers.

The mechanochemical surface functionalization of iron oxides with disordered lattices on bare iron (Fe) particles was investigated using simple milling processes to clarify the formation mechanism of the oxide layer and investigate the near-surface models with different states. The homogeneous α-Fe particles at the milling equilibrium were first prepared under an argon atmosphere. After the subsequent milling reaction of the particles with oxygen molecules, the surface analyses by X-ray diffraction and Raman and X-ray photoelectron spectroscopies revealed that the near-surface layers consisted of two iron oxide phases (α-Fe2O3 and Fe3O4) through oxygen atom diffusion, and the α-Fe2O3 was dominantly grown on the near surface. During the initial reaction, the signals from an electron spin resonance suggested the dangling bond formation on α-Fe2O3. The oxygen atoms effectively induce disordered lattices in the local area to form oxidized Fe3+ clusters, and the geometric distortion formed the dangling bonds, ...

Novel metal-like luster conductive films were prepared using straightforward chemical copolymerization of pyrrole (Py) and furfural (FFr). Critical parameters in the copolymerization such as monomer feed, reaction solvent, acid catalyst were studied to optimize their syntheses, film-forming properties, etc. These films showed a metal-like black luster and exhibited excellent mechanical properties with flexibility. The conjugate chemical bonds obtained from methine group were revealed in the copolymer film by Fourier transform infrared (FT-IR), ultraviolet–visible light (UV-vis), and 1H nuclear magnetic resonance (NMR) spectra. Differential scanning calorimetry (DSC) and cyclic voltammetry (CV) results implied that these copolymers showed better thermo and electrochemical stability. The density and smooth surface of the copolymer films contributed to the performance of metal-like luster, presenting the benefit of better surface reflection in the incident light.

The mechanochemical fabrication of the composites between carbon fibers (CFs) and nylon-6 (N6) was investigated using a milling process. By the milling, defected surfaces were generated on CFs to obtain the homogeneous length with preserving the cylindrical shape of CF. Fourier transform infrared spectra revealed that the band intensities due to C═O, C–N and O–H bondings increased with the milling. The band position of C–N was shifted to a higher wavenumber, while that of C═O did not change, implying that the main chain of N6 was dissociated at the C–N neighboring the C═O bonds by the force, and subsequently, new bonds between the N atoms of the activated N6 and the C atoms on CFs would be formed. Therefore, the efficient fabrication of the CF/N6 composite fibers with the interfacial bondings was achieved using the mechanochemical reaction.

Bamboo fibers were used as source to prepare cellulose hydrogel films for cell cultivation scaffold. The preparation of cellulose solutions was carried out by three different dissolving methods with NaOH-based and NaOH/urea aqueous solutions and DMAc/LiCl solution. Several hydrogel films were elaborated and their properties were compared to evaluate the effect of the dissolving method. It was found that tensile strength of the resultant hydrogel films increased from 21 to 66 N/mm2 when DMAc/LiCl was used instead of the NaOH/urea solution. The same tendency was observed in the obtained elongation values. Moreover, a remarkable difference in fibroblast cell cultivation was observed in higher cell density, when DMAc/LiCl method was used. The obtained results with DMAc/LiCl also were seen to be higher than the results for PS dish used as control. However, low cytocompatibility was observed when NaOH and NaOH/urea methods were used. The obtained results showed that hydrogel films elaborated with cellulose solution prepared with DMAc/LiCl method exhibited good cytocompatibility for the cell cultivation scaffold.

This study is concerned with multilayered protein adsorption on carbonate apatite (CAp) that is measured with a quartz crystal microbalance (QCM) technique. A carbonate apatite-deposited QCM sensor was prepared by electrophoretic deposition (EPD). On the CAp-deposited QCM sensor, fibrinogen adsorption followed by thrombin adsorption was investigated. The adsorption of fibrinogen on CAp led to a clear decrease in the resonance frequency of the sensor, which means that fibrinogen adsorbed on the CAp-deposited QCM sensor. The adsorbed amount of fibrinogen was larger on CAp than on a pristine sensor (Au). Although successive thrombin adsorption occurred on fibrinogen adlayers on both CAp and Au, the adsorbed amount and its conformation were different depending on the surface.

Collagen fibril membranes (CFMs) with a high mechanical property were fabricated with a lateral face evaporation method, in which type I atelocollagen extracted from tilapia scales was used. The density and thickness of the CFM obtained were 0.51 ± 0.04 mg/cm 3 and 50 ± 5 μm. The collagen fibrils in the CFM had a similar periodic stripped pattern of 67 nm with native collagen fibrils. The CFM was crosslinked in gaseous glutaraldehyde for different duration in order to increase the mechanical property. The crosslinking degrees of the CFMs analyzed by free amino groups gradually increased to 70.3 % against the exposure duration until 6 hours, and reached a plateau. The denaturation temperatures of the CFMs with the crosslinking degrees at 20.4 % to 43% were linearly increased from 49°C to 75°C. The tensile strength of the CFMs was slightly improved until the crosslinking degree at 33.3 % and then the tensile strength rapidly increased to be 68 MPa. It was suggested that a percolation phenomenon took place in the CFMs by crosslinking of collagen fibrils with polymerized GA molecules.

Hybrid nanocrystals of 8-hydroxyquinoline (8Hq) molecules and hydroxyapatite nanocrystals (HAp) were successfully prepared by a mechanochemical solid-state reaction. The hybrid nanocrystals exhibit a significant thermal stability and efficient photoluminescence peak at 500 nm, which were attributed to metal–ligand charge transfer at the interface between the oxygen atoms of 8Hq and the calcium ions of HAp, and the interfacial photofunctions were mechanochemically controlled. The interfacial bonding structures were also supported by a DV-Xα molecular orbital calculation.

The fabrication of iron–graphite composites was investigated using a milling process. Based on the milling time of the process, the average particle size of the host iron particles decreased to 10 µm. The size of the graphite particles decreased to a nanometer scale, resulting in the graphite strongly adhering to the iron surfaces. Raman spectra revealed that the graphite aromatic ring structure disappeared and the iron near-surface layer was changed to iron oxide phases. The dangling bond of the fragmented graphite combined with the oxidized iron surface by interfacial binding to efficiently form the interfacial composites.