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...

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...

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...

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...

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...

Mechanochemically activated graphite (Gp) and iron particle surfaces were prepared, and the Gp/iron composite interfaces were elucidated to utilize new functions. Activated iron particles with the oxygen atoms prepared by a milling under oxygen atmosphere were shown. Alternately, the Gp particles activated by the milling under argon atmosphere easily agglomerated because of the dangling bonds on the edge surfaces. In the composites, the interfacial bonds (e.g., Fe–O–C) between the Gp and iron oxides on the iron were clearly induced while preserving the carbon atom six-ring structures. Furthermore, the molecular orbital calculations suggested that the activated oxygen atoms in the iron oxides effectively abstract hydrogen atoms from the C–H groups of the Gp edge, resulting in the active bare carbon atoms which can form the interfacial bonds; therefore, the interfacial Fe–O–C bonds for a higher adhesive strength were successfully prepared.

Luminescent europium(III)-doped nanoporous silica nanospheres (Eu:NPS) were successfully synthesized, and a folate N-hydroxysuccinimidyl ester (FA-NHS) molecule as a targeting ligand for cancer cells was immobilized on the nanosphere surfaces through mediation of the 3-aminopropyltriethoxysilane (APTES) adlayer. The ordered nanopores were preserved by the immobilization, and the specific surface area decreased only with the APTES immobilization, suggesting that the FA-NHS was predominantly immobilized on the outer surface of the nanopores. The photoluminescence of the nanospheres functionalized with folic acid (FA) exhibited a characteristic peak due to the interactions (e.g., energy transfer) between FA and Eu(3+), and further the orange luminescence could be clearly detected by fluorescence microscopy in air and water. Furthermore, the nanospheres highly dispersed in cell culture medium exhibited nontoxicity in the cellular proliferation stages of the Hela cancer cells and NIH3T3 fibroblasts and specifically bind to the Hela cells. The nanospheres after the binding and uptake also showed intense luminescence from the outer/inner cell surfaces for the culture time of 4 days. Therefore, the luminescent FA-functionalized Eu:NPS nanospheres could be used for specific targeting and imaging abilities for cancer cells.

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.

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.

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 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.

Biological apatite (BAp) growth from a simulated body fluid on various substrate surfaces (gold (Au), titanium (Ti), and hydroxyapatite (HAp)) with and without preadsorption of fetal bovine serum protein (FBS) at the initial nucleation stage was investigated using a quartz crystal microbalance with the dissipation (QCM-D) technique. The protein composition in the FBS adlayer and viscoelastic property was elucidated by the Voigt-based viscoelastic model and antibody-binding analysis, respectively. The bare HAp effectively induced the BAp growth to increase the mass to 25.9 ± 3.2 μg cm–2 in 40 h; however, a slight increased mass of less than 1 μg cm–2 was detected on the Au and Ti, indicating the superior biocompatibility of the HAp surface. The FBS adsorption on the bare Au and Ti rapidly reached a plateau as compared to that on the HAp, and the adsorbed amount of the FBS on the HAp was approximately 2 times greater than those on the Au and Ti. The FBS adlayer on HAp showed the higher saturated ΔD/Δf value...

The photoassisted fusion of a decanethiol-passivated Au-nanoparticle film on a glass substrate by exposure to vacuum-ultraviolet (vacuum-UV) light at 172 nm was investigated and compared to that by thermal fusion. On the basis of the thermal treatment at 200 °C, the X-ray diffraction patterns indicated that the Au-nanoparticle film with the particle diameter of 2.1 nm is completely converted to a crystalline Au film, and the film surface was coarsely granular, having a roughness of several tens of nanometers by field emission-scanning electron microscopy observation. After exposure to vacuum-UV light, the UV−vis absorption spectra revealed that the surface plasmon band at 535 nm showed a red shift with the increasing exposure time, and then the absorption band at 770 nm was clearly observed at 30 min. The diameter of the fused Au nanoparticles was larger than 20 nm on the basis of a transmission electron microscopy observation. These changes indicated that the Au nanoparticles were converted to the crysta...