Laser prototyping of polymer-based nanoplasmonic components

Growing interest in the field of surface plasmon polaritons comes from a rapid advance of nanostructuring technologies. The application of two-photon polymerization by pulse laser technique for the fabrication of dielectric and metallic SPP-structures, which can be used for localization, guiding, and manipulation of plasmonic waves on a subwavelength scale, are studied. This fast technology is based on nonlinear absorption of near-infrared femtosecond laser pulses. Excitation, propagation, and interaction of SPP waves with nanostructures are controlled and studied by leakage radiation imaging. It is demonstrated that created nanostructures are very efficient for the excitation and focusing of plasmonic waves on the metal film. Examples of various plasmonic components are presented and discussed. © 2011 Nova Science Publishers, Inc. All rights reserved

Fabrication of submicron structures by three-dimensional laser lithography

As a demonstration of unique capabilities of three dimensional laser lithography, an example complex shape microobject and photonic crystals with “woodpile” structure for the infrared spectral range are fabricated by this technique. Photonic dispersion relations for the woodpile structure are calculated for different values of the permittivity contrast and the filling factor.This study was partially supported by the Government of the Russian Federation (project no. 074U01) and the Russian Foundation for Basic Research (project no. 130200186)

Scattering of a surface plasmon polariton beam by chains of dipole nanoparticles

Scattering and splitting of surface plasmon polaritons (SPPs) by a chain of strongly interacting nanoparticles located near a metal surface are numerically studied. The applied numerical model is based on the Green's function formalism and point-dipole approximation for scattering by nanoparticles. Dependencies of the splitting efficiency on the inter-particle distance in the chain and on the angle of incidence of the SPP Gaussian beam are considered. It is found that the splitting efficiency depends on the inter-particle distances especially when the angle between the SPP beam and the chain is relatively small. The role of multiple scattering in the SPP splitting by the chains of nanoparticles is also discussed. © 2008 Springer-Verlag

Stat1 nuclear translocation by nucleolin upon monocyte differentiation

BACKGROUND: Members of the signal transducer and activator of transcription (Stat) family of transcription factors traverse the nuclear membrane through a specialized structure, called the nuclear pore complex (NPC), which represents a selective filter for the import of proteins. Karyophilic molecules can bind directly to a subset of proteins of the NPC, collectively called nucleoporins. Alternatively, the transport is mediated via a carrier molecule belonging to the importin/karyopherin superfamily, which transmits the import into the nucleus through the NPC. METHODOLOGY/PRINCIPAL FINDINGS: In this study, we provide evidence for an alternative Stat1 nuclear import mechanism, which is mediated by the shuttle protein nucleolin. We observed Stat1-nucleolin association, nuclear translocation and specific binding to the regulatory DNA element GAS. Using expression of nucleolin transgenes, we found that the nuclear localization signal (NLS) of nucleolin is responsible for Stat1 nuclear translocation. We show that this mechanism is utilized upon differentiation of myeloid cells and is specific for the differentiation step from monocytes to macrophages. CONCLUSIONS/SIGNIFICANCE: Our data add the nucleolin-Stat1 complex as a novel functional partner for the cell differentiation program, which is uniquely poised to regulate the transcription machinery via Stat1 and nuclear metabolism via nucleolin

Synthesis and optical properties of silver nanoparticles in ORMOCER

Experimental results on synthesis of metal nanoparticles in ORMOCER by ion implantation are presented. Silver ions were implanted into organic/inorganic matrix at an accelerating energy of 30 keV and doses in the range of 0.25·10 17 to 0.75·10 17ion/cm 2. The silver ions form metal nanoparticles, which demonstrate surface plasmon absorption at the wavelength of 425-580 nm. The nonlinear absorption of new composite materials is measured by Z-scan technique using 150 fs laser pulses at 780 nm wavelength. ORMOCER matrix shows two-photon nonlinear absorption, whereas ORMOCER with silver nanoparticles demonstrates saturated absorption. Some optical applications of these composite materials are discussed. © Springer-Verlag 2012

Photodetachment study of the 1s3s4s ^4S resonance in He^-

A Feshbach resonance associated with the 1s3s4s ^{4}S state of He^{-} has been observed in the He(1s2s ^{3}S) + e^- (\epsilon s) partial photodetachment cross section. The residual He(1s2s ^{3}S) atoms were resonantly ionized and the resulting He^+ ions were detected in the presence of a small background. A collinear laser-ion beam apparatus was used to attain both high resolution and sensitivity. We measured a resonance energy E_r = 2.959 255(7) eV and a width \Gamma = 0.19(3) meV, in agreement with a recent calculation.Comment: LaTeX article, 4 pages, 3 figures, 21 reference

Synthesis of periodic plasmonic microstructures with copper nanoparticles in silica glass by low-energy ion implantation

Ion implantation was used to locally modify the surface of silica glass to create periodic plasmonic microstructures with Cu nanoparticles. Nanoparticles were synthesized by Cu-ion irradiation of the silica glass at the ion energy of 40 keV, dose of 5×1016 ions/cm2 and current density of 5 μA/cm2. This procedure involves low-energy ion implantation into the glass through a mask placed at the surface. Formation of nanoparticles was observed by optical spectroscopy and atomic force microscopy. The presented results clearly demonstrate how the low-energy ions can be used for the fabrication of photonic microstructures on dielectric surfaces in a single-step process. © 2012 Springer-Verlag Berlin Heidelberg

Downregulation of uPAR and Cathepsin B Induces Apoptosis via Regulation of Bcl-2 and Bax and Inhibition of the PI3K/Akt Pathway in Gliomas

Glioma is the most commonly diagnosed primary brain tumor and is characterized by invasive and infiltrative behavior. uPAR and cathepsin B are known to be overexpressed in high-grade gliomas and are strongly correlated with invasive cancer phenotypes.In the present study, we observed that simultaneous downregulation of uPAR and cathepsin B induces upregulation of some pro-apoptotic genes and suppression of anti-apoptotic genes in human glioma cells. uPAR and cathepsin B (pCU)-downregulated cells exhibited decreases in the Bcl-2/Bax ratio and initiated the collapse of mitochondrial membrane potential. We also observed that the broad caspase inhibitor, Z-Asp-2, 6-dichlorobenzoylmethylketone rescued pCU-induced apoptosis in U251 cells but not in 5310 cells. Immunoblot analysis of caspase-9 immunoprecipitates for Apaf-1 showed that uPAR and cathepsin B knockdown activated apoptosome complex formation in U251 cells. Downregulation of uPAR and cathepsin B also retarded nuclear translocation and interfered with DNA binding activity of CREB in both U251 and 5310 cells. Further western blotting analysis demonstrated that downregulation of uPAR and cathepsin B significantly decreased expression of the signaling molecules p-PDGFR-β, p-PI3K and p-Akt. An increase in the number of TUNEL-positive cells, increased Bax expression, and decreased Bcl-2 expression in nude mice brain tumor sections and brain tissue lysates confirm our in vitro results.In conclusion, RNAi-mediated downregulation of uPAR and cathepsin B initiates caspase-dependent mitochondrial apoptosis in U251 cells and caspase-independent mitochondrial apoptosis in 5310 cells. Thus, targeting uPAR and cathepsin B-mediated signaling using siRNA may serve as a novel therapeutic strategy for the treatment of gliomas

Diagnostic accuracy of a clinical diagnosis of idiopathic pulmonary fibrosis: An international case-cohort study

We conducted an international study of idiopathic pulmonary fibrosis (IPF) diagnosis among a large group of physicians and compared their diagnostic performance to a panel of IPF experts. A total of 1141 respiratory physicians and 34 IPF experts participated. Participants evaluated 60 cases of interstitial lung disease (ILD) without interdisciplinary consultation. Diagnostic agreement was measured using the weighted kappa coefficient (\u3baw). Prognostic discrimination between IPF and other ILDs was used to validate diagnostic accuracy for first-choice diagnoses of IPF and were compared using the Cindex. A total of 404 physicians completed the study. Agreement for IPF diagnosis was higher among expert physicians (\u3baw=0.65, IQR 0.53-0.72, p20 years of experience (C-index=0.72, IQR 0.0-0.73, p=0.229) and non-university hospital physicians with more than 20 years of experience, attending weekly MDT meetings (C-index=0.72, IQR 0.70-0.72, p=0.052), did not differ significantly (p=0.229 and p=0.052 respectively) from the expert panel (C-index=0.74 IQR 0.72-0.75). Experienced respiratory physicians at university-based institutions diagnose IPF with similar prognostic accuracy to IPF experts. Regular MDT meeting attendance improves the prognostic accuracy of experienced non-university practitioners to levels achieved by IPF experts