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In this study, Eu3+-containing amorphous silica nanoparticles and Eu compounds were successfully synthesized via a mechanochemical solid-state reaction between silica nanoparticles and EuCl3·6H2O. This reaction was induced by a grinding process, and the states of Eu3+ in the silica/europium composites were investigated. The silica/europium composites exhibited orange–red color luminescence owing to the 5D0–7F0, 5D0–7F1, and 5D0–7F2 transitions, which indicated the presence of Eu3+ in the silica framework and the newly formed Eu compounds such as EuOCl and Eu(OH)2Cl. The mechanochemical reaction because of the grinding process effectively induced an interaction between the silica surface and europium chloride; subsequently, Eu(OH)2Cl was formed in the silica/europium composites. Additionally, the Eu(OH)2Cl in the silica/europium composite exhibited a higher thermal stability than that of simple Eu(OH)2Cl, indicating that the mechanochemical reaction mediated the formation of Eu(OH)2Cl and new chemical bonding between the newly formed Eu(OH)2Cl and the silica surface, providing improved thermal stability to Eu(OH)2Cl. Thus, we successfully prepared silica nanoparticles containing not only Eu(III) in the silica framework but also Eu compounds that exhibit unique chemical bonding during a mechanochemical reaction.

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.

This study aims to reveal the effects of pressure during cold isostatic pressing (CIP) on the microstructure and optical properties of fluorescent HAp complexes. Although the microsturucture-dependent properties of fluorescent HAp complexes have been reported to improve the antibacterial properties of photocatalyst coating layers, the mechanism behind the changes in the fluorescence properties of highly compressed HAp complexes has not yet been unveiled. CIP was successfully used to fabricate fluorescent HAp – amino acid complexes, and their fluorescence intensities increased with increasing fabrication pressure. Peak wavelength of fluorescence emitted by the HAp – amino acid complexes exhibited yellow to red shift. Although the thickness of the amino acid layer was saturated in higher pressure cases, the concentration of amino acids increased proportionally with pressure, which suggests changes in the packing structures of the ligands in the HAp– amino acid complexes. Polarized Raman spectroscopy measurements clearly detected ligands normally arranged to the HAp layer under high pressure fabrication conditions, which can provide the tightly packed ligand structure in the HAp– amino acid complexes. These tightly packed ligand structure in the HAp– amino acid complexes could emit stronger fluorescence owing to the increased density of complexations. This newly found pressure dependency in the optical properties of HAp–amino acid complexes is beneficial for developing biocompatible fluorescence materials or enhancement agents for antibacterial coating layers.

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.

Spherical phosphorus–containing mesoporous silica (PMPS) particles were synthesized. In the PMPS particle preparation using the cationic surfactant (cetyltrimethylammonium bromide) as the template, the amphiphilic surfactant (Pluronic P123) and diethyl(2–bromoethyl)phosphonate were used for the particle shape control and the phosphorus source, respectively. Furthermore, we investigated the chemical reactions of the PMPS particles in simulated body fluid (SBF). By the phosphorus–containing, the hydroxyapatite formation and silicate ion dissolution ability on the PMPS particle surfaces were enhanced. These characteristic features will be useful for the biomedical applications such as bone formation.

We synthesized the inorganic/organic hybrid nanocrystal (EHA) by hydroxyapatite (HA) nanocrystal growth under the existence of tris(2,2,6,6-tetramethyl-3,5-heptanedionato)europium(III) (EuTH) complex. Then, folic acid derivative (FA-NHS: folate N-hydroxysuccinimidyl ester) as the targeting ligand for the HeLa cancer cells was immobilized on the EHA by the mediation of 3-aminopropyltriethoxysilane (APTES) and methyltriethoxysilane (MTES). When the FA-NHS molecular occupancy ratio on the EHA surface is around 3 to 5 %, the strong luminescence from the f-f transition of the Eu3+ ion and luminescence associated with energy transfer between the EuTH-FA monomer near 518 nm were observed. Moreover, the dispersibility in phosphate buffer saline was confirmed with immobilizing the positively-charged FA-NHS. The affinity and non-cytotoxicity between the nanocrystals and HeLa cancer cells were confirmed for 3 days. The red luminescence from the cells could be observed by fluorescence microscopy and the luminescence spectra.

We synthesized the novel inorganic-organic nanohybrid systems in hydroxyapatite (HA) nanocrystal growth processes under the presence of tris(2,2,6,6-tetramethyl-3,5-heptanedionato)europium (III) (EuTH) complex for the first time. The nanohybrid states were successfully controlled by the EuTH concentration to Ca ions in HA. The morphology of the HA was observed by a transmission electron microscope and the nanocrystalline aspect ratios were estimated to be 2.5–4.8. The segregated EuTH molecules on the HA nanocrystals covered over the a-plane in HA, leading to the effective crystal growth along with the uncovered c-plane. The luminescence properties of the nanohybrids were different from that of the EuTH itself in the solution and solid states, indicating the unique Eu3+ ion states on the HA nanocrystals because of the different ligand field symmetry. Moreover, the relative luminescence intensity ratio based on the 5D0 → 7F1 and 5D0 → 7F2 transitions in the nanohybrid became lower with increasing the EuTH concentration, suggesting that the hybridization lowered the coordination environment symmetry of Eu3+ ion. The luminescence intensity and quantum efficiency of the nanohybrids were higher than that of the EuTH itself. Therefore, the interaction at EuTH–HA interface as well as between EuTH–EuTH molecules significantly changed by the inorganic-organic hybridization under different EuTH concentrations. In future, the present hybridization technique can be applied for preparing the nanohybrids with various metallic complexes.

The cytocompatibility of the poly (dimethylsiloxane) (PDMS) surfaces can be improved by the coating with biomaterials. In this study, the methodology for the particulate titania (PT) coating on the PDMS film was investigated via the combined process of microfluidic synthesis system with spin-coating, leading to the one-step synthesis and coating. The PT was successfully deposited on the O2-plasma-treated PDMS films by mixing titanium tetraisopropoxide, isopropyl alcohol, water and octadecylamine in a microfluidic reactor and subsequently dropping. The rotation speed in the spin-coating plays an important role in the PT morphologies and deposition amounts on the PDMS films. Through the detailed investigation, the efficient condition for adhering PT to PDMS as well as inducing apatite formation from simulated body fluid was successfully discovered.

The aim of this study is to observe visible light-induced antibacterial effects of the luminescent complex of hydroxyapatite and 8-hydroxyquinoline with gray titania coating. Plasma-sprayed Hydroxyapatite (HAp) coating has been widely used as bonding between alveolar bones with dental implants. However, bacterial infection on the surfaces of dental implants has recently been reported and conventional antibacterial technologies cannot last long-term use. Therefore a novel technology using the complex of hydroxyapatite and 8-hydroxyquinoline (8-Hq) with gray titania was proposed, which can be activated by visible light. Ti2O3 powder was used in a plasma-spraying process to fabricate visible-light-sensitive titania coating. The plasma-sprayed HAp/Ti2O3 was characterized by Raman Spectroscopy, FTIR and XRD. Its photo catalytic activity was evaluated using chemiluminescence observation and antibacterial property was evaluated by optical density measurement (OD), colony forming unit (CFUs) and fluorescent microscope observation. The plasma-sprayed Ti2O3 powder revealed that its phase changed to TiO2(Rutile) though the color of the plasma-sprayed Ti2O3 powder kept dark gray, which possessed its absorbency in visible-light region. The plasma-sprayed Ti2O3 powder was then called gray titania and 1 O 2 was generated from the gray titania by irradiating three types of laser (blue, green and red). Antibacterial evaluation revealed that both the existence of the complex and the irradiation of LEDs could significantly decrease the numbers of colony forming unit (CFUs). Furthermore, HAp-8Hq complex decreased adhesion of E. coli even without light irradiation. An enhancement in the antibacterial property of HAp complexes with gray titania coating can be attributed to an increased power density of light on the surface of gray titania by fluorescence.

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.

The gold (Au) nanoparticles (NPs) with the diameter of 15–40 nm were successfully synthesized in the hierarchical hydroxyapatite (HAp) nanostructures of natural fish scale templates, which were carried out by the Au3+ ion chemisorption, reduction and calcination processes to form the AuNPs/HAp hybrids. The AuNPs size as well as the surface plasmon resonance (SPR) absorption maximum was preserved with the hybridization process. Moreover, the AuNPs/HAp hybrid nanostructures exhibited preferential protein adsorption behavior at the biological bovine serum albumin (Ab) concentration regions that correspond to be 1.5 μM in the cell culture medium and 15.1 μM in human blood, and the Ab adsorption equilibrium constant of AuNPs/HAp hybrid was higher than that of the HAp alone. The SPR absorption maxima of the Ab-adsorbed AuNPs/HAp fish scales were red-shifted as compared with those of the AuNPs/HAp fish scales. Therefore, we synthesized the AuNPs using the fish scale template to exhibit the preferential protein adsorption, which will be a great significance to research the AuNPs/HAp hybrid functions.

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.

The additive effect of TEOS and CTAB on the HAp crystal growth and HAp/silica hybrid shape was investigated. The mesoporous silica formation on the HAp nanoparticles was successfully achieved, and the SBET and RBJH values were changed with the feed Ca/P ratio. The HAp/silica hybrids exhibited the higher SBET values with the mesopores. It was suggested that the silica phase specifically interacted with the a-plane of HAp and subsequently the HAp along with the c-axis direction to be anisotropic hybrid shapes.

The hydration layers and subsequent secondary structures of adsorbed proteins on the hydroxyapatite (HA) hybridized with mesoporous silica (MS) particles (HA/MS) were investigated using an infrared spectral separation technique. The hydration structures on HA/MS were clearly different from those on the MS and HA alone, which would affect the protein absorption behaviors. In particular, HA/MS exhibited the higher protein adsorption amounts at the biological concentrations, and induced the steric conformation structures for albumin and suppressed the random structures for immunoglobulin G in the adsorption processes, suggesting the controllable interfacial layers by the hybridization of HA with MS.

For the development of next-generation protein-based biosensor surfaces, it is important to understand how functional proteins, such as fibrinogen (FBG), interact with polar substrate surfaces in order to prepare highly sensitive points of medical care diagnostics. FBG, which is a fibrous protein with an extracellular matrix, has both positively and negatively charged regions on its 3-dimensional surface, which makes interpreting how it effectively binds to polarized surfaces challenging. In this study, single-crystal LiNbO3 (LNO) substrates that have surface charges were used to investigate the adsorption of FBG protruding polar fragments on the positively and negatively charged LNO surfaces. We performed a combination of experiments and multi-scale molecular modeling to understand the binding of FBG in vacuum and water-solvated surfaces of LNO. XPS measurements showed that the FBG adsorption on LNO increased with increment in solution concentration on surfaces independent of charges. Multi-scale molecular modeling employing Quantum Mechanics, Monte Carlo, and Molecular Mechanics addressed the phenomenon of FBG fragment bonding on LNO surfaces. The binding simulation validated the experimental observation using zeta potential measurements which showed presence of solvated medium influenced the adsorption phenomenon due to the negative surface potential.

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...

Organic/inorganic hybrids of 8-hydroxyquinoline (8Hq) molecule and hydroxyapatite nanocrystal (HAp) were mechanochemically prepared. In the hybrids, a green photoluminescence peak at 500 nm newly appeared, suggesting the chemical bonding of the 8Hq molecule with the Ca 2+ ions of HAp. Then, the organic/inorganic interfacial photofunction was clarified by a molecular orbital calculation. The interfacial chemical bonding between the O and N atoms of 8Hq and the Ca 2+ ions of HAp was attributed to both covalent O Ca and ionic N Ca. The resultant wave functions revealed that the green luminescence was attributed to metal-to-ligand charge transfer (MLCT) from the O atoms of phosphate group (HAp) to the π-cloud (8Hq) in the HOMO of the hybrids. Therefore, the photofunctional interfaces of the hybrids were successfully demonstrated.

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.

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.

Cold isostatic pressing successfully formed a chelate complex of 8-hydroxyquinoline (8 Hq) molecules on plasma-sprayed hydroxyapatite (HAp) coating by solid-state reaction. The complex emits a fluorescence peak at approximately 500 nm by UV irradiation. The red shift of the fluorescence was newly observed in the cases of highly compressed complex due to π - π stacking of aromatic ring in the molecular structure of 8 Hq. The immersed complex coating in Simulated Body Fluid (SBF) demonstrated amorphous apatite precipitation and kept its fluorescence property.

A controlled sol–gel reaction of titanium tetraisopropoxide and Fe(III) acetylacetonate was conducted in the presence of octadecylamine by means of a microfluidic synthetic approach. This resulted in the formation of monodispersed titania/octadecylamine/Fe(III) acetylacetonate nanohybrids with spherical shape and magnetic/luminescent properties.

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.

The aggregation/dispersion of luminescent species is a critical factor that determines their luminescence properties. In this study, europium(III) acetylacetonate (Eu(acac)3) was doped into a titania matrix to form Eu(acac)3-doped titania particles with well-defined size and shape through a microreactor-based sol–gel approach. The morphology and structure of the as-synthesized products were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, scanning transmission electron microscopy and X-ray diffraction measurements. The Eu/Ti value of the products varied in the range from 0.125 to 5.0 and the resulting luminescence properties were examined. It should be noted that there was an optimum Eu/Ti value that exhibited the strongest luminescence. A possible reason for this phenomenon can be explained on the basis of a balance between the inter-molecular distance of Eu(acac)3 and its doped amount. The effects of the crystal phase of the titania matrix on luminescence behavior were also investigated. As a result, Eu(acac)3-doped amorphous titania demonstrated more efficient luminescence than that after calcined at 550 °C for 6 h to convert amorphous to anatase probably because of the aggregation of Eu species on the crystallite surface. The stability of the present Eu(acac)3-doped titania was confirmed by preparing thin films on a glass substrate and by applying UV/ozone treatment. As compared to bare Eu(acac)3, degradation in luminescence was suppressed in the case of Eu(acac)3-doped titania. Thus, the present titania-based hybrid with controlled Eu(acac)3 doping is useful as a stable, luminescent material for optical, biological and environmental applications.

The surfactant removal from titania/octadecylamine (ODA) hybrid spherical particles through a bake treatment, solvent-extraction or their combination was investigated. The particles after removing ODA via such approaches showed spherical shape with high specific surface area ranging from 145 to 345 m2/g and were found to be dispersible in phosphate buffered saline. The ODA removal processes clearly influenced the particle surface states, the crystallization degrees, and the dispersibility. Keywords: Bioceramics, Porous materials, Water-dispersible powder, Nanostructures, Titania

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.

This paper reviews the recent progress in the preparation of oxide-based and heteroatom-doped particles. Surfactant-templated oxide particles, e.g. silica and titania, are possible candidates for various potential applications such as adsorbents, photocatalysts, and optoelectronic and biological materials. We highlight nanoporous oxides of one element, such as silicon or titanium, and those containing multiple elements, which exhibit properties that are not achieved with individual components. Although the multicomponent nanoporous oxides possess a number of attractive functions, the origin of their properties is hard to determine due to compositional/structural complexity. Particles with a well-defined size and shape are keys for a quantitative and detailed discussion on the unique complex properties of the particles. From this viewpoint, we review the synthesis techniques of the oxide particles, which are functionalized with organic molecules or doped with heteroatoms, the physicochemical properties of the particles and the possibilities for their photofunctional applications as complex systems.

Terbium(III)-doped mesoporous silicas were synthesized, and the states of terbium ions in the silica frameworks were investigated. The mesopores were preserved upon doping at terbium ion molar concentrations relative to (Si+Tb) up to 15 mol %, indicating the interaction of terbium ions with Si–O bonds. Significant morphological changes of the particles were observed with increasing the doping concentration. The shapes of the photoluminescence spectra due to the transitions of 5D4 → 7F6 and 5D4 → 7F5 were indicative of the presence of terbium ions in the silica matrix, and the quantum efficiency (2.1–2.8%) and lifetime (1.6–1.9 ms) decreased with increasing the doping concentration up to 15 mol %. Therefore, the terbium ions are considered to be located inside the amorphous silica frameworks, where they electrostatically interact with the O atoms of silanol and siloxane groups.

Competitive adsorption of two-component solutions containing fibronectin (Fn) and albumin (Ab) on hydroxyapatite (HAp) nanocrystals was analyzed in situ using the quartz crystal microbalance with dissipation (QCM-D) technique. Adsorption of the one-component protein (Fn or Ab) and the two-component proteins adjusted to different molar ratios of Fn to Ab at a fixed Fn concentration was investigated. The frequency shift (Δf; Hz) and the dissipation energy shift (ΔD) were measured with the QCM-D technique, and the viscoelastic changes of adlayers were evaluated by the saturated ΔD/Δf value and the Voigt-based viscoelastic model. For the adsorption of the one-component protein, the Fn adlayer showed a larger mass and higher viscoelasticity than the Ab adlayer, indicating the higher affinity of Fn on HAp. For the adsorption of the two-component proteins, the viscoelastic properties of the adlayers became elastic with increase in Ab concentration, whereas the adsorption mass was similar to that of Fn in the one-component solution regardless of the Ab concentration. The specific binding mass of the Ab antibody to the adlayers increased with increase in Ab concentration, whereas that of the Fn antibody decreased. Therefore, Fn preferentially adsorbs on HAp and Ab subsequently interacts with the adlayers, indicating that the interfacial viscoelasticity of the adlayers was dominated by the interaction between Fn and Ab.