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Local hypoxia in tumors is an undesirable consequence of photodynamic therapy (PDT), which will lead to greatly reduced effectiveness of this therapy. Bioreductive pro-drugs that can be activated at low-oxygen conditions will be highly cytotoxic under hypoxia in tumors. Based on this principle, double silica-shelled upconversion nanoparticles (UCNPs) nanostructure capable of co-delivering photosensitizer (PS) molecules and a bioreductive pro-drug (tirapazamine, TPZ) were designed (TPZ-UC/PS), with which a synergetic tumor therapeutic effect has been achieved first by UC-based (UC-) PDT under normal oxygen environment, immediately followed by the induced cytotoxicity of activated TPZ when oxygen is depleted by UC-PDT. Treatment with TPZ-UC/PS plus NIR laser resulted in a remarkably suppressed tumor growth as compared to UC-PDT alone, implying that the delivered TPZ has a profound effect on treatment outcomes for the much-enhanced cytotoxicity of TPZ under PDT-induced hypoxia., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Pd and PdAu nanoparticles stabilized on multi-walled carbon nanotubes are synthesized by simple metal sputtering onto nanotubes dispersed in ionic liquids. The nanoparticles are as small as about 2 nm and possess bare surface without capping agents. The surface density of the nanoparticles can be controlled by tuning the sputtering conditions, while the sizes of the nanoparticles remain very similar. The supported Pd/PdAu nanoparticles are highly catalytically active for reduction of 4-nitrophenol, and an activity factor up to 205 s −1 g −1 is achieved. The PdAu bimetallic nanoparticles show superior catalytic performance than the Pd monometallic counterparts, indicating the synergistic effects of Pd and Au. The present approach has the merit of making alloyed nanocatalysts as simple as making corresponding elementary ones. [ABSTRACT FROM AUTHOR]

High-performance organic field-effect transistor nonvolatile memories have been achieved using sputtered C nanoparticles as the nano-floating-gate. The sputtered C nano-floating-gate is prepared with low-cost material and simple process, forming uniform and discrete charge trapping sites covered by a smooth and complete polystyrene layer. The devices show large memory window, excellent retention capability, and programming/reading/erasing/reading endurance. The sputtered C nano-floating-gate can effectively trap both holes and electrons, and it is demonstrated to be suitable for not only p-type but also n-type organic field-effect transistor nonvolatile memories. [ABSTRACT FROM AUTHOR]

A pentacene-based organic field-effect transistor nonvolatile memory, in which polystyrene covered Au nanoparticles act as the nano-floating-gate, is probed under different illumination conditions. The memory window can be greatly enlarged upon illumination depending on incident photon energy and intensity, and two light effects are proposed and discussed. The minority multiplication effect enhances the minority carrier tunneling into the nano-floating-gate, resulting in the remarkable positive V T shift. The excitation-induced injection effect is strongly photon energy dependent, and it is responsible for the significant negative V T shift. Appropriate illumination is favorable for reducing the programming/erasing voltage of organic nano-floating-gate nonvolatile memories. [ABSTRACT FROM AUTHOR]

Highlights: [•] Pd-nanoparticle–graphene hybrid is simply prepared by room-temperature ionic liquid assisted sputtering method. [•] The supported Pd nanoparticles have high loading density and uniformly small sizes of 1–2nm. [•] The hybrid is in situ characterized by the surface-sensitive ambient pressure X-ray photoelectron spectroscopy. [•] The Pd-nanoparticle–graphene hybrid shows high catalytic activity for CO oxidation. [Copyright &y& Elsevier]

Abstract: The spatial distribution of X-ray synthesized, PEG coated Au nanoparticles in cancer-bearing mice and their time dependent accumulation were investigated with inductive coupled plasma – optical emission spectroscopy (ICP-OES), transmission electron microscopy (TEM) and histological imaging. The results conclusively demonstrate that the particles strongly accumulate in tumor regions; up to ∼25 times more than in normal muscle tissue. This accumulation increases with the time after injection for up to ∼12h in tumor, spleen and liver tissues, whereas for most non-tumor regions it saturates or decreases (blood, lung, brain, heart, and kidney). The impact of this result is discussed with special emphasis on passive targeted drug delivery and could also be used for the delineation and early-stage imaging of small tumors. [ABSTRACT FROM AUTHOR]

Colloidal Ag nanoparticles were formed by X-ray irradiation in the presence of a polymer. This new synthesis method is simple, rapid and leads to a high production yield. Compared to the citrate-reduced Ag colloidal, polymer-protected Ag nanoparticles are smaller in size and more stable—and therefore suitable for biomedical application—as verified by TEM observation, XAFS measurement and optical characterization. Ag nanoparticles so produced were also visualized in solution and in real time by a visible light microscope based on dark field light scattering. The color-derived size and distribution of Ag nanoparticles correlates well with the hydrodynamic size data. [ABSTRACT FROM AUTHOR]

Abstract: Reductant, stabilizer-free colloidal gold solutions were fabricated by a new room-temperature synchrotron X-ray irradiation method. The influence of process parameters such as the pH value and the exposure time on the structure of gold nanoparticles was investigated. The mechanisms underlying the X-ray-triggered reduction of gold ions and the formation of gold clusters are discussed in detail. The X-ray irradiation derived highly concentrated gold nanoparticles are readily to be re-dispersed and possess suitable colloidal stability within cellular environment. The characterization included a study of the possible cytotoxicity for the EMT-6 tumor cell line: the negative results indicate that the gold clusters produced with our approach are biocompatible. [Copyright &y& Elsevier]

The formation of colloidal unmodified (`naked') gold nanoparticles is investigated by irradiation of a precursor solution with X-rays from a synchrotron source. An interesting morphological evolution as a function of exposure time, from cross-linked network-like structure to individual particles, has been discovered. The particle size decreased with the exposure time and was influenced by the ionic strength of the precursor solution. Contrary to γ-ray exposure, an OH radical scavenger was not required for cluster formation. [ABSTRACT FROM AUTHOR]

Abstract: We reported a simple approach to generate gold colloidals from HAuCl4 containing aqueous solution by synchrotron X-ray irradiation at room temperature. Gold colloidals were readily formed with reasonable yield. It was also observed that the addition of NaHCO3 tremendously modified the size and size distribution of gold nanoparticles. Our preliminary drug carrying experiment showed that thus produced gold nanopartricles could successfully carry anti-tumor drug and possess potential for drug delivery applications. [Copyright &y& Elsevier]

Abstract: Gel-like mixtures were prepared by mixing 1,3-dimethylimidazolium methyl sulfate with tungsten(VI) oxide nanopowder. Close interactions of the charge-enhanced C–H⋯O type have been analyzed via high-pressure infrared and Raman spectroscopy. The presence of tungsten(VI) oxide nanopowder has a negligible effect on the peak frequency of the methyl C–H stretching band. However, the pressure dependence of imidazolium C–H stretching modes displays significant changes as tungsten(VI) oxide nanoparticles were added. The results demonstrate that the imidazolium C–H⋯O3W interactions can offer an additional stability to perturb the local structure of 1,3-dimethylimidazolium methyl sulfate. Such a molecular ordering may trigger clustering of the surrounding anions and cations and interconnect neighboring WO3 nanoparticles to form physical gel. Raman spectra of a gel-like 1,3-dimethylimidazolium methyl sulfate/tungsten(VI) oxide mixture revealed a new low energy band at 788cm−1. We attribute the 788cm−1 band to the interactions between the ionic liquid and surface WO3. [Copyright &y& Elsevier]

High performance organic field-effect transistor nonvolatile memory is achieved by integrating gold nanoparticles and graphene oxide sheets as the hybrid nano-floating-gate. The device shows a large memory window of about 40 V, high ON/OFF ratio of reading current over 104, excellent programming/erasing endurance, and retention ability. The hybrid nano-floating-gate can increase the density of charge trapping sites, which are electrically separate from each other and thus suppress the stored charge leakage. The memory window is increased under illumination, and the results indicate that the photon-generated carriers facilitate the electron trapping but have almost no effect on the hole trapping. [ABSTRACT FROM AUTHOR]

Abstract: Au/TiO2 nanocomposite particles were synthesized by a method based on intense X-ray irradiation without adding any reducing agent or stabilizer. The nanocomposite exhibits promising photocatalytic and biological properties at physiologically relevant concentration ([Au]=0.028mM, [TiO2]=0.5mM). The structure and photocatalysis were examined by X-ray diffraction, electron microscopy and ultraviolet–visible spectroscopy demonstrating that gold nanoparticles of 2–5nm size were successfully deposited on TiO2 nanoparticle surfaces. The nanocomposite exhibited good colloidal stability within a typical cellular environment and was nontoxic to cancer cell according to evaluations under controlled conditions. The Au/TiO2 nanoparticles were also found to enhance the photocatalytic efficiency of UV radiation and even more that of X-ray radiation. In vitro studies indicated that the cell-killing effect under X-ray irradiation is more pronounced with the addition of Au/TiO2 nanoparticles than of bare TiO2 nanoparticles. [Copyright &y& Elsevier]