BaGdF5 Nanophosphors Doped with Different Concentrations of Eu3+ for Application in X-ray Photodynamic Therapy

X-ray photodynamic therapy (XPDT) has been recently considered as an efficient alternative to conventional radiotherapy of malignant tissues. Nanocomposites for XPDT typically consist of two components—a nanophosphor which re-emits X-rays into visible light that in turn is absorbed by the second component, a photosensitizer, for further generation of reactive oxygen species. In this study, BaGdF₅ nanophosphors doped with different Eu:Gd ratios in the range from 0.01 to 0.50 were synthesized by the microwave route. According to transmission electron microscopy (TEM), the average size of nanophosphors was ~12 nm. Furthermore, different coatings with amorphous SiO₂ and citrates were systematically studied. Micro-CT imaging demonstrated superior X-ray attenuation and sufficient contrast in the liver and the spleen after intravenous injection of citric acid-coated nanoparticles. In case of the SiO₂ surface, post-treatment core–shell morphology was verified via TEM and the possibility of tunable shell size was reported. Nitrogen adsorption/desorption analysis revealed mesoporous SiO₂ formation characterized by the slit-shaped type of pores that should be accessible for methylene blue photosensitizer molecules. It was shown that SiO₂ coating subsequently facilitates methylene blue conjugation and results in the formation of the BaGdF₅: 10% Eu³⁺@SiO₂@MB nanocomposite as a promising candidate for application in XPDT.     

Natural organic matter (NOM) induces oxidative stress in freshwater amphipods Gammarus lacustris Sars and Gammarus tigrinus (Sexton)

Humic substances comprise the majority of natural organic matter (NOM) on Earth, including dissolved organic matter in freshwater systems. Recent studies show that these substances directly interact with aquatic organisms as chemical stressors. The aim of the present study was to investigate the mode of action of dissolved NOM on the freshwater amphipods Gammarus lacustris Sars and Gammarus tigrinus (Sexton), and in particular, to determine if NOM induces or promotes internal oxidative stress. NOM was isolated by reverse osmosis from a brown-water lake in Brandenburg State, Germany. Oxidative stress markers, such as lipid peroxidation, cell internal hydrogen peroxide concentration, as well as peroxidase, catalase and glutathione S-transferase activities, were quantified. Exposure of both amphipod species to NOM caused a significant increase in lipid peroxidation, hydrogen peroxide concentration, catalase, peroxidase and glutathione S-transferase activities. Both species showed a two-stage antioxidant response: the first stage allowed the organisms to effectively eliminate ROS and to protect cells from damage, whereas the second stage leads to H2O2 accumulation in combination with destruction of lipid structures in the cells and, finally, functional damage or even death of the organism.     

Creativity as flexible cognitive control.

Creative individuals have been described in terms suggestive of greater automatic processing (e.g., defocused attention, looser associations) and greater controlled processing (e.g., greater abilities to focus while working on a creative task). Both views cannot be correct from a static ability-related perspective. On the other hand, both views could be correct if creative individuals are better able to modulate the functioning of their cognitive control system in a context-sensitive manner. The present study (N = 50) assessed individual differences in creativity in terms of original responses on the Torrance Test of Creative Thinking (Torrance, 1974) and also in terms of creative behavior on the Creative Achievement Questionnaire (Carson, Peterson, & Higgins, 2005). The same participants performed a color–word Stroop task. Creative individuals were neither more nor less capable of overriding cognitive conflicts on incongruent (relative to congruent) Stroop trials. On the other hand, creative individuals displayed more flexible cognitive control, as defined by greater cognitive control modulation from trial to trial. Implications for theories of creativity and its underlying processing basis are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Oxidation of Fine Tantalum Particles: Metastable Intermediates and Multistep Kinetics

Oxidation of Metals - The metastable tantalum suboxides have been found to be a cause of complicated oxidation behaviour of fine tantalum particles when heated in air at moderate temperatures. Fine...     

Photoactivatable nanoCRISPR/Cas9 System Based on crRNA Reversibly Immobilized on Carbon Nanoparticles

Here, we proposed a new approach to engineering a photoactivatable CRISPR/Cas9 gene-editing system. The novel nanoCRISPR/Cas9 system is based on the use of auxiliary photocleavable oligodeoxyribonucleotides (PC-DNAs) complementary to crRNA. PC-DNAs contained up to three UV-sensitive linkers made of 1-(2-nitrophenyl)-1,2-ethanediol inside the oligonucleotide chain. Immobilizing PC-DNAs on the surface of carbon nanoparticles through 3′-terminal pyrene residue provided sufficient blocking of crRNA (and corresponding Cas9 activity) before UV irradiation and allows for crRNA release after UV irradiation at 365 nm, which restores Cas9 activity. We optimized the length of blocking photocleavable oligonucleotide, number of linkers, time of irradiation, and the type of carbon nanoparticles. Based on the results, we consider the nanoCRISPR/Cas9 system involving carbon-encapsulated iron nanoparticles the most promising. It provides the greatest difference of functional activity before/after irradiation and can be used in prospective for magnetic field-controlled delivery of CRISPR system into the target cells or tissues and spatiotemporal gene editing induced by UV irradiation.     

Controlled copolymerization of acrylonitrile with methyl acrylate and dimethyl itaconate via ARGET ATRP mechanism

The peculiarities of controlled copolymerization of acrylonitrile with methyl acrylate and dimethyl itaconate in the presence of copper-based catalytic system were investigated. It was shown that the polymerization proceeds in a controlled mode in accordance with ARGET ATRP mechanism. The increase of molecular weights in a strict agreement with theoretically predicted values is observed. The formation of copolymers was confirmed by NMR and MALDI TOF MS analysis. The introduction of mentioned monomers to acrylonitrile results in slight decrease of the polymerization rate. The performed calorimetric investigations showed the smoothing of exothermic effect of the oxidative stabilization of formed copolymers.     

Heterostructures based on Pd–Au nanoparticles and cobalt phthalocyanine for hydrogen chemiresistive sensors

In this work, the effect of Pd, Au and PdAu nanoparticles on sensor response of cobalt phthalocyanine films to hydrogen was studied. For this purpose, novel heterostructures based on cobalt phthalocyanine and PdAu nanoalloys were obtained by a combination of vacuum thermal evaporation and pulsed metalorganic chemical vapor deposition (MOCVD) and investigated as active layers for hydrogen detection. The structural features and phase composition of the prepared heterostructures were studied by the techniques of X-ray diffraction, transmission electron microscopy and electron diffraction. The concentration of metal nanoparticles in the samples was determined by inductively coupled plasma atomic emission spectroscopy (ICP-AES). The chemiresistive sensor response of CoPc/M (M = Pd, Au, Pd_0.2Au_0.8 and Pd_0.8Au_0.2) to hydrogen (100–400 ppm, room temperature) was compared with that of bare CoPc films. It was shown that the sensor response of the investigated heterostructures to hydrogen (300 ppm) increased in the order CoPc (0.2%) < CoPc/Pd_0.2Au_0.8 (1.9%) ~ CoPc/Au (2.2%) < CoPc/Pd (2.7%) < CoPc/Pd_0.8Au_0.2 (5.6%).     

Improvement of enzyme electrocatalysis using substrate containing electroactive polymers. Towards limiting efficiencies of bioelectrocatalysis

Direct electrocatalysis by the enzymes in the absence of any freely diffusing mediators requires proper orientation of the protein macromolecule on the electrode surface. We report a conception on how to improve efficiency of bioelectrocatalysis using electroactive polymers containing analogues of the enzyme substrates (usually acting as artificial donors-acceptors). Indeed, substrate analogues having affinity to terminal redox groups of the enzymes can anchor them in an optimal orientation upon immobilization. The improvement of bioelectrocatalysis using such electroactive polymers is reported for different enzymes: hydrogenases and cellobiose dehydrogenase. Highly efficient electrocatalysis by hydrogenases was determined by thermodynamics of the catalyzed reaction confirming the direct bioelectrocatalysis. For hydrogenases immobilized over viologen substituted conducting polymers the limiting performance characteristics in bioelectrocatalysis have been achieved.     

2′‐Bispyrene‐Modified 2′‐O‐Methyl RNA Probes as Useful Tools for the Detection of RNA: Synthesis,Fluorescent Properties,and Duplex Stability

The synthesis and properties two series of new 2′‐O‐methyl RNA probes, each containing a single insertion of a 2′‐bispyrenylmethylphosphorodiamidate derivative of a nucleotide (U, C, A, and G), are described. As demonstrated by UV melting studies, the probes form stable complexes with model RNAs and DNAs. Significant increases (up to 21‐fold) in pyrene excimer fluorescence intensity were observed upon binding of most of the probes with complementary RNAs, but not with DNAs. The fluorescence spectra are independent of the nature of the modified nucleotides. The nucleotides on the 5′‐side of the modified nucleotide have no effect on the fluorescence spectra, whereas the natures of the two nucleotides on the 3′‐side are important: CC, CG, and UC dinucleotide units on the 3′‐side of the modified nucleotide provide the maximum increases in excimer fluorescence intensity. This study suggests that these 2′‐bispyrene‐labeled 2′‐O‐methyl RNA probes might be useful tools for detection of RNAs.     

Effect of Central Administration of Brain-Derived Neurotrophic Factor (BDNF) on Behavior and Brain Monoamine Metabolism in New Recombinant Mouse Lines Differing by 5-HT1A Receptor Functionality

Experiments were carried out on recombinant B6.CBA-D13Mit76C (B6-M76C) and B6.CBA-D13Mit76B (B6-M76B) mouse lines created by transferring a 102.73–118.83 Mbp fragment of chromosome 13, containing the 5-HT_1A receptor gene, from CBA or C57BL/6 strains to a C57BL/6 genetic background, correspondingly. We have recently shown different levels of 5-HT1A receptor functionality in these mouse lines. The administration of BDNF (300 ng/mouse, i.c.v.) increased the levels of exploratory activity and intermale aggression only in B6-M76B mice, without affecting depressive-like behavior in both lines. In B6-M76B mice the behavioral alterations were accompanied by a decrease in the 5-HT_2A receptor functional activity and the augmentation of levels of serotonin and its main metabolite, 5-HIAA (5-hydroxyindoleacetic acid), in the midbrain. Moreover, the levels of dopamine and its main metabolites, HVA (homovanillic acid) and DOPAC (3,4-dihydroxyphenylacetic acid), were also elevated in the striatum of B6-M76B mice after BDNF treatment. In B6-M76C mice, central BDNF administration led only to a reduction in the functional activity of the 5-HT_1A receptor and a rise in DOPAC levels in the midbrain. The obtained data suggest the importance of the 102.73–118.83 Mbp fragment of mouse chromosome 13, which contains the 5-HT_1A receptor gene, for BDNF-induced alterations in behavior and the brain monoamine system.