Weon-Sik Chae

Novel synthesis of organic nanowires and their optical propertiesElectronic supplementary information (ESI) available: experimental section and Figs. S1 and S2. See http://www.rsc.org/suppdata/cc/b1/b109881k/

Aligned nanowires of organic luminescent material were prepared by introducing the organic luminants into nanochannels of variable size in an anodic aluminum oxide (AAO) membrane, and the emission spectra from these nanowire arrays exhibited novel size-dependent luminescent properties.

Emission characteristics of CdS nanoparticles induced by confinement within MCM-41 nanotubes

Nanosize CdS particles confined in siliceous MCM-41 channels were prepared by using reversed micelles as an insertion carrier. As-made CdS in MCM-41 host shows photoluminescence (PL) signals from both band-edge and surface defect state recombination. Calcinated CdS in the host, however, presents relatively suppressed surface defect state emission compared with band-edge emission. Such emission characteristics after calcination is ascribed to the reduced probability of recombination through deeply trapped surface defect states compared with direct excitonic recombination, which is possibly due to surface capping of the CdS nanoparticles by the host nanochannels.

Accelerated healing with the use of a silk fibroin membrane for the guided bone regeneration technique.

OBJECTIVE The purpose of this study was to evaluate the bone regeneration ability of silk fibroin (SF) membrane. STUDY DESIGN Fourier-transform infrared (FT-IR) and solubility test against distilled water were performed with 3 different types of SF membrane (SM1, SM2, and SM3). Subsequently, microscopic computerized tomography (μ-CT) and histomorphometric analyses were performed in rabbit calvarial defect model after SF membrane application at 4 and 8 weeks after surgery. RESULTS FT-IR showed that the conformation of the SF membrane was a random coil structure and that SM1 was the least soluble. When SM1 was used in the animal model, the groups with SM1 had significantly higher new bone formation than the uncovered control in both the μ-CT and the histomorphometric analyses (P < .05). CONCLUSIONS The SF membrane had more new bone formation compared with the uncovered control.

Advanced porous gold nanofibers for highly efficient and stable molecular sensing platforms.

Porous gold nanofibers are fabricated through templated electrochemical routes in porous alumina membranes. Gold-silver alloy is electrochemically deposited in the nanocylinders of the porous alumina templates and then the silver phase is selectively dealloyed. The resulting nanofibers present a nanoporous network with a pore dimension of approximately 10 nm and notable surface-enhanced Raman scattering (SERS) efficiencies which are at least seven times higher than from the smooth solid gold nanofibers without porosity. The relative SERS enhancement on porous gold is directly proved by imaging with a Raman microscope for conjugated porous gold/solid gold single nanorods.

Aerosol Deposition of Hydroxyapatite and 4-Hexylresorcinol Coatings on Titanium Alloys for Dental Implants

PURPOSE Aerosol deposition is a newly developed technique, and it can deliver the drug from a hydroxyapatite (HA)-coated surface. 4-Hexylresorcinol (4-HR) is a well-known antiseptic. The influence of the 4-HR component of HA coatings on titanium surfaces was studied in vitro and in vivo. MATERIALS AND METHODS X-ray diffraction and Fourier transform infrared techniques were used for the evaluation of the coating. The cellular response of the coating was evaluated by scanning electron microscopic study, MTT assay, alkaline phosphatase assay, and osteocalcin assay. In addition, the dental implant was coated with HA or HA + 4-HR. The implant was installed into the tibia of a rabbit after contamination by Aggregatibacter actinomycetemcomitans. The torque test and histologic analysis were then performed at 8 weeks after the operation. RESULTS By use of an aerosol deposition technique, the combination of HA and 4-HR was successfully coated onto a titanium surface, which was confirmed by x-ray diffraction and Fourier transform infrared techniques. MG63 cells attached more rapidly to the HA + 4-HR coating than to the HA-only coating. The HA + 4-HR coating had significantly increased osteocalcin expression and alkaline phosphatase activity compared with the HA-only coating (P < .05). The dental implant coated with HA + 4-HR had a significantly higher removal torque value than that coated with HA alone at 8 weeks after surgery (P < .05). On histologic analysis, both the bone formation value and the bone-to-implant contact value were significantly higher in the HA + 4-HR group than in the HA-only group at 8 weeks after surgery (P < .05). CONCLUSIONS Collectively, the HA + 4-HR-coated dental implant had clear advantages over the HA-coated dental implant. Therefore HA + 4-HR coatings can be considered for patients who need immediate implant installation after tooth extraction or who have poor-quality bone.

Synthesis and characterization of Ni magnetic nanoparticles in AlMCM41 host

Superparamagnetic nickel nanoparticles were prepared by incorporating nickel ion into AlMCM41 as a nanoreactor and then reduced with sodium borohydride or H2 gas. Products were characterized by elemental analysis, transmission electron microscopy, X-ray powder diffraction, and magnetic susceptibility. The nickel particle size and blocking temperature depend on the reduction method. q 2002 Elsevier Science Ltd. All rights reserved.

Optical resonance and charge transfer behavior of patterned WO3 microdisc arrays

One- to three-dimensional alignments of semiconductors on the micro- or nanoscale have been achieved to tailor their opto-physicochemical properties and improve their photoelectrochemical (PEC) performance. Here, to the best of our knowledge, we report for the first time the fabrication of vertically aligned, well-ordered WO3 microdisc arrays via an electrodeposition process on lithographically patterned indium tin oxide (ITO) substrates as well as their geometry-specific photoelectrochemical properties. The as-fabricated WO3 microdisc arrays exhibit enhanced light absorption as well as facilitated charge separation, leading to significantly higher PEC performance than WO3 films. A finite-difference time-domain simulation of a single WO3 microdisc indicates that strong optical resonances occur particularly in the central part of the microdisc, leading to enhanced optical absorption. A time-resolved photoluminescence study further reveals that the average lifetime of charge carriers (τ) in a microdisc array is shorter than that in a film by ∼60%. The reductively deposited Au particles are localized on the side of the microdisc and ITO substrate, which suggests that the photogenerated electrons are transferred to the same location. In addition, the oxidative deposition of FeOOH particles on the top surface and side of a microdisc indicates hole transfer pathways at the same location. This downward transfer of electrons and upward transfer of holes lead to efficient charge separation, and the radial direction appears to be the most preferred shortcut for the carriers inside the bulk of a microdisc.

4-Hexylresorcinol inhibits transglutaminase-2 activity and has synergistic effects along with cisplatin in KB cells

Resistance to chemotherapy is very important in the prognosis of tumors. Transglutaminase-2 (TG-2) mediated chemotherapy resistance has been widely reported. The objective of this study was to demonstrate the effect of 4-hexylresorcinol (4-HR) on TG-2 activity in nasopharyngeal squamous cell carcinoma cells (KB cells). Treatment with a mixture of 4-HR and cisplatin significantly decreased KB cell viability compared to treatment by cisplatin alone at 10 µg/ml (p<0.001). 4-HR inhibited TG-2 activity compared to cisplatin alone at 5, 10 and 20 µg/ml (p = 0.001, 0.001 and 0.003, respectively). Nuclear translocation of TG-2 was also inhibited by 4-HR treatment. 4-HR treatment also increased the fluorescence life-time of DAPI significantly compared to the untreated control or the cisplatin treated group (p<0.001). In conclusion, 4-HR inhibited TG-2 activity and showed a synergistic effect on tumor cell growth inhibition with cisplatin.

A Facile Fabrication of Fe

Monodispersed superparamagnetic magnetite submicron particles were synthesized by using a one-step solvothermal method. Increasing the volume ratio of ethylene glycol/diethylene glycol (EG/DEG) shows a gradual increase in the size of primary nanograin and secondary Fe3O4 submicroparticles. To induce the photo-magnetic functionality, we have successfully synthesized the multifunctional core-shell (Fe3O4/ZnO) submicron particles by atomic layer deposition (ALD) method. Microstructure and magnetic properties of the multifunctional core/shell submicron particles are investigated by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), vibrating sample magnetometry (VSM), and photoluminescence spectroscopy.

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The aim of this study was to evaluate the in vivo bone regeneration capability of alginate (AL), AL/hydroxyapatite (HA), and AL/HA/silk fibroin (SF) composites. Forty Sprague Dawley rats were used for the animal experiments. Central calvarial bone (diameter: 8.0 mm) defects were grafted with AL, AL/HA, or AL/HA/SF. New bone formation was evaluated by histomorphometric analysis. To demonstrate the immunocompatibility of each group, the level of tumor necrosis factor (TNF)-α expression was studied by immunohistochemistry (IHC) and quantitative reverse transcription polymerase chain reaction (qRT-PCR) at eight weeks post implantation. Additionally, osteogenic markers, such as fibroblast growth factor (FGF)-23, osteoprotegerin (OPG), and Runt-related transcription factor (Runx2) were evaluated by qPCR or IHC at eight weeks post implantation. The AL/HA/SF group showed significantly higher new bone formation than did the control group (p = 0.044) and the AL group (p = 0.035) at four weeks post implantation. Additionally, the AL/HA/SF group showed lower relative TNF-α mRNA levels and higher FGF-23 mRNA levels than the other groups did at eight weeks post implantation. IHC results demonstrated that the AL/HA/SF group had lower TNF-α expression and higher OPG and Runx2 expression at eight weeks post implantation. Additionally, no evidence of the inflammatory reaction or giant cell formation was observed around the residual graft material. We concluded that the AL/HA/SF composite could be effective as a scaffold for bone tissue engineering.