Microstructured optical waveguide-based endoscopic probe coated with silica submicron particles

Microstructured optical waveguides (MOW) are of great interest for chemical and biological sensing. Due to the high overlap between a guiding light mode and an analyte filling of one or several fiber capillaries, such systems are able to provide strong sensitivity with respect to variations in the refractive index and the thickness of filling materials. Here, we introduce a novel type of functionalized MOWs whose capillaries are coated by a layer-by-layer (LBL) approach, enabling the alternate deposition of silica particles (SiO2) at different diameters—300 nm, 420 nm, and 900 nm—and layers of poly(diallyldimethylammonium chloride) (PDDA). We demonstrate up to three covering bilayers consisting of 300-nm silica particles. Modifications in the MOW transmission spectrum induced by coating are measured and analyzed. The proposed technique of MOW functionalization allows one to reach novel sensing capabilities, including an increase in the effective sensing area and the provision of a convenient scaffold for the attachment of long molecules such as protein

Современные методы анализа и средства измерения сорбционных свойств магнитосорбентов

Introduction. Research in a field of new sorption materials obtaining have been presented in this article. These sorbents have magnetic properties and they can be used for water purification from ions of heavy metals (HM), petroleum and petroleum products (PP). Compositional sorption material (CSM) has been made with the use of ferritized galvanic sludge (FGS) as a magnetic component and paraffin as a binder substance. Materials and methods. The following objects of the research were chosen in this work: industrial waste - galvanic sludge (GS), FGS, paraffin. Modern methods of the research have been used at work implementation: photometry, IR-spectrophotometry, scanning electron microscopy. Obtaining accurate and reliable results of the experiment were provided by the use of standard methods, established in federal environmental regulatory document (PND F), verifiable measuring instruments and standard samples. Results. FGS after a thermal processing has sorption properties in relation to ions of heavy metals Fe2+, Fe3+ and Cu2+. The material CSM can adsorb petroleum and PP. Discussion and conclusions. The sorption materials on the basis of industrial waste - GS were obtained and studied. These sorbents have magnetic properties which will be useful at water treatment; a saturated material can be extracted from a purified environment by magnetic separation.Введение. В настоящей статье представлены исследования в области получения новых сорбционных материалов, обладающих магнитными свойствами, для очистки воды от тяжелых металлов (ТМ), нефти и нефтепродуктов (НП). Композиционный сорбционный материал (КСМ) изготавливали с использованием ферритизированного гальваношлама (ФГШ) в качестве магнитного компонента и парафина как связующего вещества. Материалы и методы. В работе были выбраны следующие объекты исследования: промышленный отход -гальванический шлам (ГШ), ФГШ и ферритизированный гальваношлам после термической обработки (ФГШтерм), парафин. При выполнении работы использовались следующие современные методы исследования: фотометрия, ИК-спектрофотометрия, сканирующая электронная микроскопия. Получение точных и достоверных результатов эксперимента обеспечивалось за счет применения стандартных методик, установленных в природоохранных нормативных документах федерального уровня (ПНД Ф), поверенных средств измерений и стандартных образцов (СО). Результаты исследования. Установлено, что ФГШтерм. обладает сорбционными свойствами по отношению к ионам Fe2+, Fe3+ и Cu2+. Материал КСМ отличается способностью к сорбции нефти и НП. Обсуждение и заключение. В результате исследования получены и изучены сорбционные материалы на основе промышленных отходов - ГШ. Наличие магнитных свойств разрабатываемых сорбентов предполагает магнитоуправляемое проведение процесса сорбции с возможностью извлечения насыщенного сорбента из очищаемой среды магнитной сепарацией

SERS and Indicator Paper Sensing of Hydrogen Peroxide Using Au@Ag Nanorods

The detection of hydrogen peroxide and the control of its concentration are important tasks in the biological and chemical sciences. In this paper, we developed a simple and quantitative method for the non-enzymatic detection of H2O2 based on the selective etching of Au@Ag nanorods with embedded Raman active molecules. The transfer of electrons between silver atoms and hydrogen peroxide enhances the oxidation reaction, and the Ag shell around the Au nanorod gradually dissolves. This leads to a change in the color of the nanoparticle colloid, a shift in LSPR, and a decrease in the SERS response from molecules embedded between the Au core and Ag shell. In our study, we compared the sensitivity of these readouts for nanoparticles with different Ag shell morphology. We found that triangle core–shell nanoparticles exhibited the highest sensitivity, with a detection limit of 10−4 M, and the SERS detection range of 1 × 10−4 to 2 × 10−2 M. In addition, a colorimetric strategy was applied to fabricate a simple indicator paper sensor for fast detection of hydrogen peroxide in liquids. In this case, the concentration of hydrogen peroxide was qualitatively determined by the change in the color of the nanoparticles deposited on the nitrocellulose membrane

Monitoring of copper nanoparticle penetration into dentin of human tooth in vitro

Study of the penetration depth of synthesized copper nanoparticles into cut samples of human dentin was conducted. The scanning electron microscopy was used to determine the elemental composition of fresh transverse cleavage of the dentin cut for determination of the copper nanoparticles penetration with an effective antiseptic effect. The morphology of the cut surface of the dentin of a human tooth was studied and the lower limit of the diffusion boundary was determined. It was found that copper nanoparticles penetrate into the dentin cut to a depth of ~ 1.8 μm with the diffusion coefficient of 1.8×10–11 cm2/s. Despite the rather small size of the synthesized copper nanoparticles (20-80 nm), a rather small penetration depth can be explained by the high aggregation ability of copper nanoparticles, as well as the ability of a micellar solution of sodium dodecyl sulfate, in which nanoparticles were stabilized, to form conglomerates in micelles of much larger sizes

Features of Microstructure and Texture Formation of Large-Sized Blocks of C11000 Copper Produced by Electron Beam Wire-Feed Additive Technology

The paper investigated the possibility of obtaining large-sized blocks of C11000 copper on stainless steel substrates via electron beam wire-feed additive technology. The features of the microstructure and grain texture formation and their influence on the mechanical properties and anisotropy were revealed. A strategy of printing large-sized C11000 copper was determined, which consists of perimeter formation followed by the filling of the internal layer volume. This allows us to avoid the formation of defects in the form of drops, underflows and macrogeometry disturbances. It was found that the deposition of the first layers of C11000 copper on a steel substrate results in rapid heat dissipation and the diffusion of steel components (Fe, Cr and Ni) into the C11000 layers, which promotes the formation of equiaxed grains of size 8.94 ± 0.04 μm. As the blocks grow, directional grain growth occurs close to the <101> orientation, whose size reaches 1086.45 ± 57.13 μm. It is shown that the additive growing of large-sized C11000 copper leads to the anisotropy of mechanical properties due to non-uniform grain structure. The tensile strength in the opposite growing direction near the substrate is 394 ± 10 MPa and decreases to 249 ± 10 MPa as the C11000 blocks grows. In the growing direction, the tensile strength is 145 ± 10 MPa

Modern methods of analysis and instruments measuring sorption properties of magnetic sorbents

Introduction. Research in a field of new sorption materials obtaining have been presented in this article. These sorbents have magnetic properties and they can be used for water purification from ions of heavy metals (HM), petroleum and petroleum products (PP). Compositional sorption material (CSM) has been made with the use of ferritized galvanic sludge (FGS) as a magnetic component and paraffin as a binder substance. Materials and methods. The following objects of the research were chosen in this work: industrial waste - galvanic sludge (GS), FGS, paraffin. Modern methods of the research have been used at work implementation: photometry, IR-spectrophotometry, scanning electron microscopy. Obtaining accurate and reliable results of the experiment were provided by the use of standard methods, established in federal environmental regulatory document (PND F), verifiable measuring instruments and standard samples. Results. FGS after a thermal processing has sorption properties in relation to ions of heavy metals Fe2+, Fe3+ and Cu2+. The material CSM can adsorb petroleum and PP. Discussion and conclusions. The sorption materials on the basis of industrial waste - GS were obtained and studied. These sorbents have magnetic properties which will be useful at water treatment; a saturated material can be extracted from a purified environment by magnetic separation

Composite magnetite and protein containing CACO3 crystals: external manipulation and vaterite → calcite recrystallization-mediated release performance

Biocompatibility and high loading capacity of mesoporous CaCO3 vaterite crystals give an option to utilize the polycrystals for a wide range of (bio)applications. Formation and transformations of calcium carbonate polymorphs have been studied for decades, aimed at both basic and applied research interests. Here, composite multilayer-coated calcium carbonate polycrystals containing Fe3O4 magnetite nanoparticles and model protein lysozyme are fabricated. The structure of the composite polycrystals and vaterite -> calcite recrystallization kinetics are studied. The recrystallization results in release of both loaded protein and Fe3O4 nanoparticles (magnetic manipulation is thus lost). Fe3O4 nanoparticles enhance the recrystallization that can be induced by reduction of the local pH with citric acid and reduction of the polycrystal crystallinity. Oppositely, the layer-by-layer assembled poly(allylamine hydrochloride)/poly(sodium styrenesulfonate) polyelectrolyte coating significantly inhibits the vaterite -> calcite recrystallization (from hours to days) most likely due to suppression of the ion exchange giving an option to easily tune the release kinetics for a wide time scale, for example, for prolonged release. Moreover, the recrystallization of the coated crystals results in formulation of multilayer capsules keeping the feature of external manipulation. This study can help to design multifunctional microstructures with tailor-made characteristics for loading and controlled release as well as for external manipulation

Composite Magnetite and Protein Containing CaCO₃ Crystals. External Manipulation and Vaterite → Calcite Recrystallization-Mediated Release Performance

Biocompatibility and high loading capacity of mesoporous CaCO₃ vaterite crystals give an option to utilize the polycrystals for a wide range of (bio)­applications. Formation and transformations of calcium carbonate polymorphs have been studied for decades, aimed at both basic and applied research interests. Here, composite multilayer-coated calcium carbonate polycrystals containing Fe₃O₄ magnetite nanoparticles and model protein lysozyme are fabricated. The structure of the composite polycrystals and vaterite → calcite recrystallization kinetics are studied. The recrystallization results in release of both loaded protein and Fe₃O₄ nanoparticles (magnetic manipulation is thus lost). Fe₃O₄ nanoparticles enhance the recrystallization that can be induced by reduction of the local pH with citric acid and reduction of the polycrystal crystallinity. Oppositely, the layer-by-layer assembled poly­(allylamine hydrochloride)/poly­(sodium styrenesulfonate) polyelectrolyte coating significantly inhibits the vaterite → calcite recrystallization (from hours to days) most likely due to suppression of the ion exchange giving an option to easily tune the release kinetics for a wide time scale, for example, for prolonged release. Moreover, the recrystallization of the coated crystals results in formulation of multilayer capsules keeping the feature of external manipulation. This study can help to design multifunctional microstructures with tailor-made characteristics for loading and controlled release as well as for external manipulation