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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 ∼12 h 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. Refereed/Peer-reviewed

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] = 0.028 mM, [TiO2] = 0.5 mM). The structure and photocatalysis were examined by X-ray diffraction, electron microscopy and ultraviolet-visible spectroscopy demonstrating that gold nanoparticles of 2-5 nm 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. (C) 2009 Elsevier B.V. All rights reserved.

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.

The fabrication of gold Fresnel zone plates, by a combination of e-beam lithography and electrodeposition, with a 30 nm outermost zone width and a 450 nm-thick structure is described. The e-beam lithography process was implemented with a careful evaluation of applied dosage, tests of different bake-out temperatures and durations for the photoresist, and the use of a developer without methylisobutylketone. Electrodeposition with a pulsed current mode and with a specially designed apparatus produced the desired high-aspect-ratio nanostructures. The fabricated zone plates were examined by electron microscopy and their performances were assessed using a transmission X-ray microscope. The results specifically demonstrated an image resolution of 40 nm.

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.

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 gamma-ray exposure, an OH radical scavenger was not required for cluster formation.

A nanofabrication approach based on advanced e-beam lithography and electrodeposition successfully produced high-resolution (≈40 nm line width) metal structures with high aspect ratio (>12) and high density. The combination of these characteristics is essential for hard-x-ray optical components such as zone plates, for x-ray lithography masks and for other devices.

The removal of algal biomass and algal extracellular products (ECPs) from eutrophic water is studied using various physical chemical methods including coagulation/precipitation, powdered activated carbon (PAC) adsorption and combination of coagulation/ precipitation and activated carbon adsorption. The removal efficiencies of algae and TOC are 96% and 81%, respectively, by coagulation/ precipitation method. Moreover, dissolved organic carbon (DOC) is divided into four groups based on molecular weight distribution. It is found that coagulation/ precipitation process has good DOC removal efficiency for high molecular weight groups whereas PAC adsorption is particularly effective of the removal of DOC of low molecular weight. It is also discovered that the removal efficiency is synergistic by coagulation/ precipitation followed by PAC adsorption. The formations of THMFP/ DOC and AOXFP/DOC are higher with high molecular weight groups than those with low molecular weight groups.

The fabrication of devices to focus hard x-rays is one of the most difficult—and important—challenges in nanotechnology. Here we show that Fresnel zone plates combining 30 nm external zones and a high aspect ratio finally bring hard x-ray microscopy beyond the 30 nm Rayleigh spatial resolution level and measurable spatial frequencies down to 20–23 nm feature size. After presenting the overall nanofabrication process and the characterization test results, we discuss the potential research impact of these resolution levels.

We explored a very interesting gold nanoparticle system?pegylated gold in colloidal solution?and analyzed its uptake by mice colorectal adenocarcinoma CT26 tumor cells and the impact on the cell's response to x-ray irradiation. We found that exposure to polyethylene glycol (PEG) modified ('pegylated') 4.7 ? 2.6?nm gold nanoparticles synthesized by a novel synchrotron-based method enhances the response of CT26 cells to x-ray irradiation. Transmission electron microscopy (TEM) and confocal microscopy revealed that substantial amounts of such nanoparticles are taken up and absorbed by the cells and this conclusion is supported by quantitative induced coupled plasma (ICP) results. Standard tests indicated that the internalized particles are highly biocompatible but strongly enhance the cell damage induced by x-ray irradiation. Synchrotron radiation Fourier transform infrared (SR-FTIR) spectromicroscopy analyzed the chemical aspects of this phenomenon: the appearance of C = O stretching bond spectral features could be used as a marker for cell damage and confirmed the enhancement of the radiation-induced toxicity for cells.

We used an approach combining Inductively Coupled Plasma (ICP) etching process and high resolution electron beam lithography and successfully fabricate high aspect ratio zone plate for hard‐x‐ray applications. The electron beam lithography defines the pattern with outmost zone dimension smaller than 100nm while the consequently ICP produced high aspect ratio structures. Both chacteristics, high resolution patterning and high aspect ratio are required to produce zone plate devices for multi‐keV x‐rays. We demonstrated that a zone plate with a 60nm outmost zone and a thickness of 500nm is achievable by this approach.

The comparative analysis of the dry etching of FLARE 2.0 and a-C:F, which represent two different depositions techniques of organic low-k polymers was investigated. In our damascene architecture, the etching stop layer or hard-mask of both SiOF; SiO 2 was studied. Especially, the SiOF providing lower dielectric constant than SiO 2 would reduce entire effective dielectric constant. The etch rate and etching rate selectivity was optimized by changing content ratio between CHF 3 , N 2 , and O 2 . Furthermore, the bias power, RF power; and gas flows were changed to control the etch profile. The SEM results showed that the better etch profile can be obtained at higher bias power. There were some deviation between etching rate of blanket with the case of patterned wafer. The distribution density of the reactant etching gas in sub-um gap different from blanket surface of wafer was major dynamics. Due to this phenomena, the etching rate became nonlinear function of process time T etch in the trenches/vias with smaller dimension.

The polyethylene glycol (PEG) modified gold nanoparticle complex was synthesized by a one-solution synchrotron x-ray irradiation method. The impact on the structure and morphology of the gold nanoparticles of process parameters such as the PEG molecular weight, the PEG/gold molar ratio and the x-ray dosage were investigated. The size of PEG modified gold particles was found to decrease with increasing PEG addition and x-ray dosage. With the capability to monitor the absorption spectra in situ during the fast synthesis process, this opens the way to accurate control of the size and distribution. PEG chains with an intermediate length (MW6000) were found optimal for size control and colloidal stability in biologically relevant media. Our x-ray synthesized PEG-gold nanoparticles could find interesting applications in nanoparticle-enhanced x-ray tumour imaging and therapy.

Dose measurements based on methylene blue (MB) bleaching, widely used for ultraviolet light, can also be applied to X-rays including very high flux levels. This method has been tested by using both MB bleaching and Fricke dosimetry for a conventional monochromatic X-ray source and then for 'white-beam' synchrotron radiation. The results show that MB bleaching dosimetry can easily measure X-ray doses up to at least 10(5) Gy s(-1), as long as the MB concentration is sufficiently high. This condition can be verified from the deviations from linearity of the bleaching versus exposure time.

We investigated iron oxide nanoparticles with two different surface modifications, dextran coating and cross-linked dextran coating, showing that their different internalization affects their capability to enhance radiation damage to cancer cells. The internalization was monitored with an ultrahigh resolution transmission x-ray microscope (TXM), indicating that the differences in the particle surface charge play an essential role and dominate the particle-cell interaction. We found that dextran-coated iron oxide nanoparticles cannot be internalized by HeLa and EMT-6 cells without being functionalized with amino groups (the cross-linked dextran coating) that modify the surface potential from -18 mV to 13.4 mV. The amount of cross-linked dextran-coated iron oxide nanoparticles uptaken by cancer cells reached its maximum, 1.33 x 10(9) per HeLa cell, when the co-culture concentration was 40 microg Fe mL(-1) or more. Standard tests indicated that these internalized nanoparticles increased the damaging effects of x-ray irradiation, whereas they are by themselves biocompatible. These results could lead to interesting therapy applications; furthermore, iron oxide also produces high contrast for magnetic resonance imaging (MRI) in the diagnosis and therapy stages.

Real-time X-ray microscopy was used to study the influence of hydrogen-bubble formation on the morphology of ramified zinc electrodeposit. The experimental results show that when intense hydrogen bubbling occurs at high potential, the morphology of the ramified zinc deposit changes from dense-branching to fern-shaped dendrite. The fern-shaped dendrite results in part from the constricted growth due to hydrogen bubbles but also from the highly concentrated electric field. The fern-shaped dendrite morphology was observed during the early stages of electroplating for both the potentiostatic and galvanostatic modes; however, the deposit plated in the galvanostatic mode densified via lateral growth during the later plating stages. This indicates that potentiostatic plating for which the hydrogen-bubble formation steadily occurs throughout the electrodeposition process is better than galvanostatic plating for fabricating fern-shaped deposits, which are ideal electrodes for Zn-air batteries due to the relatively large specific area. (C) 2008 The Electrochemical Society.