A folic acid conjugated silica-titania porous hollow nanosphere for improved topical photodynamic therapy.

The folic acid conjugated hollow nanosphere is used to encapsulate protoporphyrin IX and is utilized for photodynamic therapy. This system represents a 3.33 times higher photodynamic efficiency than previous protoporphyrin IX-based systems. The result proposes a new opportunity for effective photodynamic therapy of folate receptor positive tumor cells.

SiO(2) /TiO(2) hollow nanoparticles decorated with Ag nanoparticles: enhanced visible light absorption and improved light scattering in dye-sensitized solar cells.

Hollow SiO2 /TiO2 nanoparticles decorated with Ag nanoparticles (NPs) of controlled size (Ag@HNPs) were fabricated in order to enhance visible-light absorption and improve light scattering in dye-sensitized solar cells (DSSCs). They exhibited localized surface plasmon resonance (LSPR) and the LSPR effects were significantly influenced by the size of the Ag NPs. The absorption peak of the LSPR band dramatically increased with increasing Ag NP size. The LSPR of the large Ag NPs mainly increased the light absorption at short wavelengths, whereas the scattering from the SiO2 /TiO2 HNPs improved the light absorption at long wavelengths. This enabled the working electrode to use the full solar spectrum. Furthermore, the SiO2 layer thickness was adjusted to maximize the LSPR from the Ag NPs and avoid corrosion of the Ag NPs by the electrolyte. Importantly, the power conversion efficiency (PCE) increased from 7.1 % with purely TiO2 -based DSSCs to 8.1 % with HNP-based DSSCs, which is an approximately 12 % enhancement and can be attributed to greater light scattering. Furthermore, the PCEs of Ag@HNP-based DSSCs were 11 % higher (8.1 vs. 9.0 %) than the bare-HNP-based DSSCs, which can be attributed to LSPR. Together, the PCE of Ag@HNP-based DSSCs improved by a total of 27 %, from 7.1 to 9.0 %, due to these two effects. This comparative research will offer guidance in the design of multifunctional nanomaterials and the optimization of solar-cell performance.

Fabrication of barium- and strontium-doped silica/titania hollow nanoparticles and their synergetic effects on promoting neuronal differentiation by activating ERK and p38 pathways.

Pristine, barium-doped, and strontium-doped hollow nanoparticles (p-HNPs, Ba-HNP, and Sr-HNP; HNPs) are prepared by sonication-mediated etching and redeposition (SMER) method and alkali-earth-metal hydroxide solution treatment. The HNPs are investigated to facilitate synergetic neuronal differentiation through alkali-earth-metal doping and in conjunction with nerve growth factor (NGF). PC12 cells are used as model cells for neuronal differentiation. The differentiation efficiency is improved in the presence of the HNPs+NGF, and the neurite length is in the order of Sr-HNP+NGF > Ba-HNP+NGF > p-HNP+NGF > NGF. Silica/titania have increasing effect on both differentiation efficiency and neurite length, and doped barium/strontium influences additional elongation of the average neurite length. Take advantage of hollow structure, NGF is encapsulated into HNPs, and they are further applied for directly inducing differentiation. The maximum differentiation efficiency is 67% in presence of the NGF-encapsulated Sr-HNP, which was 1.3 times higher than previous research. Furthermore, the neurite length is also 2.7 times higher than MnO2 decorated poly(3,4-ethylenedioxythiophene) nanoellipsoids. Ba- and Sr-HNP may offer a possibility for novel application of metal-hybrid nanomaterials for cell differentiation, and can be expanded to other cellular applications.

Enhanced frequency response of a highly transparent PVDF-graphene based thin film acoustic actuator.

A high-performance polyvinylidene fluoride (PVDF) based thin film acoustic actuator with chemical vapor deposition (CVD) graphene electrodes was successfully fabricated. Importantly, it showed 60, 19, and 22% enhancement in the bass, middle and treble frequency response, respectively.

High-performance Förster resonance energy transfer (FRET)-based dye-sensitized solar cells: rational design of quantum dots for wide solar-spectrum utilization.

High-performance Förster resonance energy transfer (FRET)-based dye-sensitized solar cells (DSSCs) have been successfully fabricated through the optimized design of a CdSe/CdS quantum-dot (QD) donor and a dye acceptor. This simple approach enables quantum dots and dyes to simultaneously utilize the wide solar spectrum, thereby resulting in high conversion efficiency over a wide wavelength range. In addition, major parameters that affect the FRET interaction between donor and acceptor have been investigated including the fluorescent emission spectrum of QD, and the content of deposited QDs into the TiO2 matrix. By judicious control of these parameters, the FRET interaction can be readily optimized for high photovoltaic performance. In addition, the as-synthesized water-soluble quantum dots were highly dispersed in a nanoporous TiO2 matrix, thereby resulting in excellent contact between donors and acceptors. Importantly, high-performance FRET-based DSSCs can be prepared without any infrared (IR) dye synthetic procedures. This novel strategy offers great potential for applications of dye-sensitized solar cells.

Designed synthesis of SiO2/TiO2 core/shell structure as light scattering material for highly efficient dye-sensitized solar cells.

SiO2/TiO2 core/shell nanoparticles (STCS-NPs) with diameters of 110, 240, and 530 nm were fabricated to investigate the influence of the size and refractive index of light-scattering particles on light-scattering properties. The optical properties of STCS-NPs were evaluated and compared with SiO2-NPs and TiO2-NPs. The structure of STCS-NPs, consisting of a low refractive index core and high refractive index shell, provides efficient light scattering. The optimized anode film with STCS-NPs had ca. 20% improved power conversion efficiency (PCE).

Selective semihydrogenation of alkynes on shape-controlled palladium nanocrystals.

A systematic study on the selective semihydrogenation of alkynes to alkenes on shape-controlled palladium (Pd) nanocrystals was performed. Pd nanocrystals with a cubic shape and thus exposed {100} facets were synthesized in an aqueous solution through the reduction of Na2PdCl4 with L-ascorbic acid in the presence of bromide ions. The Pd nanocubes were tested as catalysts for the semihydrogenation of various alkynes such as 5-decyne, 2-butyne-1,4-diol, and phenylacetylene. For all substrates, the Pd nanocubes exhibited higher alkene selectivity (>90 %) than a commercial Pd/C catalyst (75-90 %), which was attributed to a large adsorption energy of the carbon-carbon triple bond on the {100} facets of the Pd nanocubes. Our approach based on the shape control of Pd nanocrystals offers a simple and effective route to the development of a highly selective catalyst for alkyne semihydrogenation.

Characterizing size and porosity of hollow nanoparticles: SAXS, SANS, TEM, DLS, and adsorption isotherms compared.

A combination of experimental methods, including transmission and grazing incidence small-angle X-ray scattering (SAXS and GISAXS), small-angle neutron scattering (SANS), transmission electron microscopy (TEM), dynamic light scattering (DLS), and N(2) adsorption-desorption isotherms, was used to characterize SiO(2)/TiO(2) hollow nanoparticles (HNPs) of sizes between 25 and 100 nm. In the analysis of SAXS, SANS, and GISAXS data, the decoupling approximation and the Percus-Yevick structure factor approximation were used. Brunauer-Emmett-Teller, t-plot, and a spherical pore model based on Kelvin equation were applied in the treatment of N(2) isotherms. Extracted parameters from the scattering and TEM methods are the average outer and inner diameters and polydispersity. Good agreement was achieved between different methods for these extracted parameters. Merits, advantages, and disadvantages of the different methods are discussed. Furthermore, the combination of these methods provided us with information on the porosity of the shells of HNPs and the size of intrawall pores, which are critical to the applications of HNPs as drug delivery vehicles and catalyst supports.

Designed architecture of multiscale porous TiO2 nanofibers for dye-sensitized solar cells photoanode.

Multiscale porous (MSP) TiO(2) nanofibers (NFs) were fabricated using a simple electrospinning and etching process with TiO(2)/SiO(2) composite NFs for high-efficiency dye-sensitized solar cells (DSSCs). TiO(2) NFs with different pore sizes (small, large, and multiscale) were prepared using SiO(2) nanoparticles of various sizes. The surface area of the MSP TiO(2) NFs was nine times higher than that of pristine TiO(2) NFs, providing sufficient dye adsorption for light harvesting as well as efficient paths for electrolyte contact. Moreover, the one-dimensional structure provides efficient light scattering and fast electron transport. As a result, DSSCs exhibited an enhanced current density (J(sc)) of 16.3 mA cm(-2) and a high photoconversion efficiency (η) of 8.5%, greater than those of conventional photoelectrodes made of TiO(2) nanoparticles (J(sc) of 12.0 mA cm(-2) and η of 6.0 %).

Efficient intracellular delivery of camptothecin by silica/titania hollow nanoparticles.

Silica/titania hollow nanoparticles (HNPs) with 50 nm were fabricated by using the dissolution and redeposition method and modified with anti-[human epidermal growth factor receptor 2] monoclonal antibody (herceptin), and their application as camptothecin (CPT) delivery agents to human breast cancer SK-BR-3 cells was investigated. Although the diameter of herceptin-modified HNPs (HER-HNP) is smaller than that of other reported mesoporous silica nanoparticles, the extensive hollow cavity of HNPs (ca. 30 nm) allowed the loading of a large amount of CPT. CPT-loaded HER-HNP (HER-HNP-CPT) did not release CPT in phosphate-buffered saline over a period of 24 h, however, HER-HNP-CPT in a hydrophobic solvent released its entire load of CPT. In addition, HER-HNPs were efficiently internalized owing to their herceptin conjugation and optimized size. To evaluate in vitro antitumor efficacy, apoptosis/necrosis and viability of HER-HNP-CPT-treated cells were investigated. When the cells were treated with HER-HNP-CPT for 30 min, a few apoptotic cells were observed. After 24 h, the viability of HER-HNP-CPT-treated SK-BR-3 decreased to 60 %, which revealed highly efficient chemotherapy. However, CPT loaded into HNP or HER-HNP had no significant effects on the viability of macrophages. Judging from these data, HER-HNPs are very suitable for application in anticancer therapy. A HER-HNP-CPT drug delivery system offers a new direction for a hydrophobic anticancer drug carrier and can be expanded to practical applications with further studies.

Synthesis of titania embedded silica hollow nanospheres via sonication mediated etching and re-deposition.

Titania embedded silica hollow nanospheres were synthesized from sonication-mediated etching and re-deposition of silica/titania core/shell nanospheres. The designed structure of the hollow nanospheres was proved to be a key factor for the charge trapping/detrapping and resulting bistability in non-volatile organic bistable memory devices (OBDs).

Cellular uptake, cytotoxicity, and innate immune response of silica-titania hollow nanoparticles based on size and surface functionality.

Silica-titania hollow nanoparticles (HNPs) with uniform diameters of 25, 50, 75, 100, and 125 nm were fabricated by dissolution and redeposition method in order to evaluate size dependent cellular response. Surface-modified HNPs with cationic, anionic, and neutral functional group were prepared by silane treatment. We systematically investigated cellular internalization, toxicity, and innate immune response of HNPs in human breast cancer (SK-BR-3) and mouse alveolar macrophage (J774A.1) cells. Size- and surface functionality-dependent cellular uptake of HNPs was investigated by fluorescence labeling (fluorescein isothiocyanate), inductively coupled plasma-emission spectroscopy, and ultrastructural resolution using transmission electron microscopy. Viability, reactive oxygen species, and apoptosis/necrosis of HNP-treated J774A.1 revealed the size-dependent phenomenon. Innate immune response of HNP-treated macrophages was measured by three cytokines such as interleukin-1, interleukin-6, and tumor necrosis factor α. Among the HNPs of different sizes, 50-nm HNPs demonstrated the highest toxic influence on macrophages. Among the HNPs with surface functionalities, cationic HNPs demonstrated the most toxic effect on J774A.1 and the highest uptake efficiency. The toxicity results of HNP-treated macrophages were consistent with the cellular internalization efficiency. These findings provide size- and surface functionality-dependent nanotoxicity and uptake of HNPs, and lead to HNPs for bioapplications such as drug delivery and imaging probe.

Geometrical study of electrorheological activity with shape-controlled titania-coated silica nanomaterials.

The titania-coated silica nanomaterials with three different shapes (nanosphere, nanorod, nanotube) are fabricated to examine the influence of particle geometry on ER fluid in nanometer-size region. The effect of particle geometry on ER activity is studied by varying the geometric aspect ratio of dispersing materials. The ER activities of titania-coated silica nanomaterials exhibit a dependence on their aspect ratio. Interestingly, the shear stress of titania-coated silica nanomaterials based ER fluids increases with increasing the aspect ratio. Geometrical study is performed to give deep insights into the primary factors that determine the ER activity. It is believed that the geometrical effect originated from high aspect ratio played a dominant role in enhancing the performance of ER fluid. Furthermore, the dielectric property analysis based on dielectric loss model clarifies that an increase in aspect ratio has been coupled with the larger achievable polarizability and short relaxation time of interfacial polarization. Consequently, the increment in aspect ratio has strong influence on ER activity, provides outstanding enhancement in shear stress value of titania-coated silica nanotube based ER fluid.

Swim training increases ovalbumin induced active systemic anaphylaxis in mice.

Aerobic training can be defined as any physical exercise that increases the heart rate and enhances the body's intake of oxygen long enough to benefit the condition of the body. Running, cycling, and swimming are examples of aerobic activities. In recent years, the importance of sports in everyday life has been rapidly increasing. Moderate exercise appears to stimulate the immune system. However, healthy elite runners often complain about bronchial symptoms after heavy exercise. Exercise-induced asthma and active systemic anaphylaxis are the most common problems seen in these individuals. The inter-relationship of exercise and the allergy response has not been well studied. This study was designed to examine the effects of regular swim training on body weight, spleen index, the number of lymphocytes, scoring of active systemic anaphylactic shock, proliferative activity of splenic lymphocytes and cytokine levels in BALB/c mice. Thirty mice (6 weeks old) were involved in this study and they were divided into 3 groups: a control group (Control, n = 10), a sensitized group (Sensitized, n = 10), and a sensitized-trained group (Sen-trained, n = 10). The sen-trained group was studied after 10 weeks of regular swim training. All data were expressed as mean and standard deviation by using SPSS (ver.10.0). The swim training caused a decrease in body weight (p < 05), an increase of spleen index, active systemic anaphylaxis, lymphocyte proliferation (stimulated with ovalbumin), and cytokine levels (especially IL-4) when comparing the sen-trained group to the sensitized group (p < .05). These data indicate that there is a link between allergy anaphylaxis and regular swim training. This may be due to increased lymphocyte proliferation (stimulated with ovalbumin), ASAS (active systemic anaphylactic shock) score, and IL-4 cytokine levels after exercise.