Composites of heterospin molecular magnet [EuIII(SQ)3bipy] in a polystyrene (PS) matrix have been synthesized. This complex [EuIII(SQ)3bipy] contains four paramagnetic centers - the Eu3+ ion and three SQ ligands (SQ—3,6-di-tert-butyl benzoquinone radical anion); bipy (bipyridyl) is diamagnetic. It has been established that intensive mechanical activation of [EuIII(SQ)3bipy]/PS samples leads to an reological explosion, as a result of which radio frequency superradiance, the appearance of free electrons and the formation of Eu metal nanoparticles are observed. The duration of this process is 10 ns.

New viral infections, due to their rapid spread, lack of effective antiviral drugs and vaccines, kill millions of people every year. The global pandemic SARS-CoV-2 in 2019–2021 has shown that new strains of viruses can widespread very quickly, causing disease and death, with significant socio-economic consequences. Therefore, the search for new methods of combating different pathogenic viruses is an urgent task, and strategies based on nanoparticles are of significant interest. This work demonstrates the antiviral adsorption (virucidal) efficacy of nanoparticles of porous silicon (PSi NPs) against various enveloped and non-enveloped pathogenic human viruses, such as Influenza A virus, Poliovirus, Human immunodeficiency virus, West Nile virus, and Hepatitis virus. PSi NPs sized 60 nm with the average pore diameter of 2 nm and specific surface area of 200 m2/g were obtained by ball-milling of electrochemically-etched microporous silicon films. After interaction with PSi NPs, a strong suppression of the infectious activity of the virus-contaminated fluid was observed, which was manifested in a decrease in the infectious titer of all studied types of viruses by approximately 104 times, and corresponded to an inactivation of 99.99% viruses in vitro. This sorption capacity of PSi NPs is possible due to their microporous structure and huge specific surface area, which ensures efficient capture of virions, as confirmed by ELISA analysis, dynamic light scattering measurements and transmission electron microscopy images. The results obtained indicate the great potential of using PSi NPs as universal viral sorbents and disinfectants for the detection and treatment of viral diseases.

Methods for creating various 3D morphologies of composites based on chitosan and copper nanoparticles stabilized by it in carbonic acid solutions formed under high pressure of saturating CO2 were developed. This work includes a comprehensive analysis of the regularities of copper nanoparticles stabilization and reduction with chitosan, studied by IR and UV-vis spectroscopies, XPS, TEM and rheology. Chitosan can partially reduce Cu2+ ions in aqueous solutions to small-sized, spherical copper nanoparticles with a low degree of polydispersity; the process is accompanied by the formation of an elastic polymer hydrogel. The resulting composites demonstrate antimicrobial activity against both fungi and bacteria. Exposing the hydrogels to the mixture of He or H2 gases and CO2 fluid under high pressure makes it possible to increase the porosity of hydrogels significantly, as well as decrease their pore size. Composite capsules show sufficient resistance to various conditions and reusable catalytic activity in the reduction of nitrobenzene to aniline reaction. The relative simplicity of the proposed method and at the same time its profound advantages (such as environmental friendliness, extra purity) indicate an interesting role of this study for various applications of materials based on chitosan and metals.

Composites of a heterospin molecular magnet [Eu(III)(SQ)3bipy] in a polystyrene (PS) matrix have been synthesized. The [EuIII(SQ)3bipy] complex contains four paramagnetic centers—the Eu3+ ion and three SQ ligands (SQ-3,6-di-tert-butyl benzoquinone radical anion); bipy (bipyridyl) is diamagnetic. It has been established that intensive mechanical activation of [Eu(III)(SQ)3bipy]/PS samples leads to a rheological explosion, as a result of which radio frequency superradiance, the appearance of free electrons and the formation of Eu metal nanoparticles are observed. The duration of this process is 10 ns.

The creation of biocompatible composite hydrogels from renewable biopolymers with stabilized functional platinum nanoparticles seems to be an important scientific task. The formation of such hydrogels in a unique medium of carbonic acid under high pressure CO(2)is promising due to its sterilizing ability under pressure, biocompatibility after decompression and environmental friendliness. In the present work, stable chitosan hydrogels with platinum nanoparticles were obtained in such solutions. The hydrogel nature of the composites was confirmed by rotational rheology. The physicochemical characteristics were studied using Fourier transform infrared, X-ray photoelectron, ultraviolet-visible spectroscopies, transmission electron, scanning electron and atomic force microscopies. It was found that nanoparticles of oxidized Pt of approximately 4.5 nm in size are stabilized by chitosan in the composite. The resulting chitosan/Pt hydrogels were also tested for antimicrobial activity and shown strong activity against Gram-positive bacteria (B. subtilisandB. coagulans) and slight activity againstE. coli.

This study is aimed at developing sensing schemes without obtaining selective receptors. A series of simple carbocyanine dyes was synthesized, whose emission was quenched in water with formation of nanoparticles in the range of 20-100 nm. Fluorescence in near-IR region is "turned on" in the presence of a drug cation of middle molecular weight (400-700 Da) and sodium dodecyl sulfate (SDS), as well as anionic drugs and a cationic surfactant (cetyltrimethylammonium bromide, CTAB). Aggregates (clusters) up to 100-200 nm in size were detected using dynamic light scattering (DLS) and Rayleigh light scattering (RLS) techniques in the systems: cationic analyte-SDS, carbocyanine dye-CTAB, and in all brightly fluorescent ternary systems dye-surfactant-analyte. Small ions (<200 Da) incapable of multi point binding do not form the aggregates or cause the emission enhancement. The "turn-on" signal is only observed at the surfactant submicellar concentrations insufficient to solubilize the dye nanoparticles. Based on these findings, we suggest a rapid and simple method for the detection of >= 4.10(-5) mol/L of neomycin in urine. The proposed strategy paves the way for developing more selective methods. (C) 2020 Elsevier B.V. All rights reserved.

Metal–polymer nanocomposite polyvinyltriazole–silver nanoparticles were obtained using one-pot synthesis in irradiated aqueous solutions of 1-vinyl-1,2,4-triazole (VT) and silver ions. Gel permeation chromatography data show that upon radiation initiation, the molecular weight of poly(1-vinyl-1,2,4-triazole) increases with increasing monomer concentration. To study the kinetics of polymerization and the features of the radiation–chemical formation of nanoparticles, UV-Vis spectroscopy was used. TEM images show a relatively small average size of the forming nanoparticles (2–3 nm) and a narrow size distribution, which shows the effective stabilization of nanoparticles by triazole substituents at a molar ratio of VT and silver ions of 25/1. The addition of ethyl alcohol was used to increase the efficiency of synthesis and suppress the crosslinking of macromolecules in solution. The results of the work show that aqueous–alcoholic solutions of 1 wt.% VT can be used to obtain soluble nanocomposite materials. 10 wt.% monomer solutions have prospects for use in the preparation of polymer gels filled with nanoparticles.

Influenza A virus envelope contains lipid molecules of the host cell and three integral viral proteins: major hemagglutinin, neuraminidase, and minor M2 protein. Membrane-associated M1 matrix protein is thought to interact with the lipid bilayer and cytoplasmic domains of integral viral proteins to form infectious virus progeny. We used small-angle X-ray scattering (SAXS) and complementary techniques to analyze the interactions of different components of the viral envelope with M1 matrix protein. Small unilamellar liposomes composed of various mixtures of synthetic or “native” lipids extracted from Influenza A/Puerto Rico/8/34 (H1N1) virions as well as proteoliposomes built from the viral lipids and anchored peptides of integral viral proteins (mainly, hemagglutinin) were incubated with isolated M1 and measured using SAXS. The results imply that M1 interaction with phosphatidylserine leads to condensation of the lipid in the protein-contacting monolayer, thus resulting in formation of lipid tubules. This effect vanishes in the presence of the liquid-ordered (raft-forming) constituents (sphingomyelin and cholesterol) regardless of their proportion in the lipid bilayer. We also detected a specific role of the hemagglutinin anchoring peptides in ordering of viral lipid membrane into the raft-like one. These peptides stimulate the oligomerization of M1 on the membrane to form a viral scaffold for subsequent budding of the virion from the plasma membrane of the infected cell.

Influenza A virus is a serious human pathogen that assembles enveloped virions on the plasma membrane of the host cell. The pleiomorphic morphology of influenza A virus, represented by spherical, elongated, or filamentous particles, is important for the spread of the virus in nature. Using fixative protocols for sample preparation and negative staining electron microscopy, we found that the recombinant A/WSN/33 (H1N1) (rWSN) virus, a strain considered to be strictly spherical, may produce filamentous particles when amplified in the allantoic cavity of chicken embryos. In contrast, the laboratory WSN strain and the rWSN virus amplified in Madin-Darby canine kidney cells exhibited a spherical morphology. Next-generation sequencing (NGS) suggested a rare Ser126Cys substitution in the M1 protein of rWSN, which was confirmed by the mass spectrometric analysis. No structurally relevant substitutions were found by NGS in other proteins of rWSN. Bioinformatics algorithms predicted a neutral structural effect of the Ser126Cys mutation. The mrWSN_M1_126S virus generated after the introduction of the reverse Cys126Ser substitution exhibited a similar host-dependent partially filamentous phenotype. We hypothesize that a shortage of some as-yet-undefined cellular components involved in virion budding and membrane scission may result in the appearance of filamentous particles in the case of usually "nonfilamentous" virus strains.

The specific features of the formation of metal nanoparticles under X-ray radiation in interpolyelectrolyte complex (IPEC) films based on polyacrylic acid and polyethyleneimine with different silver ion content were studied. IPEC films were irradiated in aqueous-alcoholic medium. Electron microscopy demonstrated that the formation of silver nanoparticles occurred in zones regularly located by film thickness. It was found that nanoparticle size and spatial distribution in IPEC films depended on the initial concentration of silver ions within the sample and on the absorbed dose of radiation. The obtained film nanocomposites are promising objects for application as antibacterial and catalytic materials.

Tuning the size and structure of bimetallic nanostructures is for the design of functional compounds with desirable properties. In this paper, the mechanisms that control radiation-induced assembly of bimetallic core-shell nanoparticles in polyelectrolyte matrices are discussed. The stages of Ag/Cu nanoparticle formation in the films of poly(acrylic acid)-poly(ethylenimine) complexes have been studied for the first time using X-ray diffraction analysis including synchrotron techniques combined with electron microscopy. The generation of silver nanostructures proceeds via their parallel nucleation and growth during the entire process of bimetallic nanoparticles formation. The sizes of shells are controlled by the competition between the growth of silver nanostructures and the formation of shells. Copper shells are generated in two stages: (1) ultrasmall nanostructures, which are slowly formed at the first stage, prevent the growth of silver nuclei; (2) as the shell improves, the growth rate of copper nanostructures increases dramatically. The results obtained demonstrate the possibility of single-stage controllable radiation-initiated synthesis of core-shell bimetallic nanoparticles directly in interpolyelectrolyte films.

Ultradisperse polytetrafluoroethylene is separated into fractions soluble and insoluble in supercritical carbon dioxide. The initial polymer and its soluble and insoluble fractions are impregnated with silver(I) (1,5-cyclooctadiene)-1,1,1,5,5,5-hexafluoroacetylacetonate in supercritical carbon dioxide solution for 6.6 h under thermodynamic conditions at 65°С and 8 MPa followed by reduction of the metal in an atmosphere of hydrogen for 6 h at 65°С and 1.2 MPa. According to X-ray fluorescence analysis, the content of the metal attains 2.4 wt %. Ag-polymer composites are studied by X-ray fluorescence spectroscopy, transmission electron microscopy, small-angle X-ray scattering, and X-ray photoelectron spectroscopy. It is shown that silver in the form of nanoparticles with a size of 1.0–7.5 nm is localized largely in the soluble low molecular weight fraction.

Разработан способ синтеза дисперсных платино-вольфрамовых композитов по схеме «в одном сосуде». Сначала, с использованием гексакарбонила вольфрама в качестве прекурсора в растворе в сверхкритическогом диоксиде углерода (СК-С0) в присутствии кислорода как окислителя, промотирующего термодеструкцию прекурсора, были синтезированы дисперсные частицы оксида вольфрама с размером зерна около 100 нм и размером агрегатов 200-500 нм. Затем, на эти дисперсные подложки нанесены платиновые наночастицы в две стадии: 1) формирование пленки платиносодержащего прекурсора (диметил(1,5-циклооктадиен)платины или гексафторацетилацетонат платины) осаждением их из раствора в СК-С0; 2) термодеструкция прекурсора. Размер наночастиц платины составлял 2,3 + 0,7 нм при использовании первого прекурсора и 3,5 + 0,8 нм - при использовании второго. Полученные композиты характеризуются сравнительно узким распределением наночастиц металла по размерам и их равномерным распределением по поверхности частиц дисперсного носителя. A one-pot synthesis of dispersed platinum-tungsten composites was developed. Initially, using tungsten hexacarbonyl as a precursor in solution in supercritical CO in the presence of oxygen as an oxidizer promoting thermal decomposition of the precursor, dispersed particles of tungsten oxide with a grain size of about 100 nm and an aggregate size of 200-500 nm were synthesized. Then, these dispersed particles were used as a substrate for the subsequent deposition of platinum nanoparticles, which included two stages: 1) forming a film of an organometallic precursor by deposition from a solution in supercritical CO and 2) thermal decomposition of the precursor. As the two types of platinum precursors, the dimethyl(1,5-cyclooctadiene)platinum and platinum hexafluoroacetylacetonate, which both are soluble in sc CO, were used as the typical ones in the practice of similar studies. The size of the formed platinum nanoparticles was 2.3 + 0,7 nm using the former precursor and 3.5 + 0,8 nm using the latter. The obtained composites are characterized by a relatively narrow size distribution of the noble metal nanoparticles and their uniform distribution over the surface of the particles of the dispersed carrier. Such materials may be of interest for (electro)cata-lysis tasks.

We report on the synthesis of composites based on poly(styrene) (PS) and CdSe/ZnS quantum dots (QDs). The reduction of terminal functional group of RAFT polymerized PS to thiol group allows for a partial substitution of low molecular weight ligands at the surface of CdSe/ZnS QDs by a polymer. The combination of TEM and FTIR data results in the model of the composite formation with PS macromolecules wrapped around QDs. The photoluminescence (PL) of QDs in PS-CdSe/ZnS composites decreases with an additional embedding of Au nanoparticles (NPs). The reason of the PL drop observed is analyzed in terms of combined inner filter effects and the influence of dielectric properties of the medium surrounding Au NPs embedded in PS-CdSe/ZnS composites. The calculations of the radial distribution function of QDs regarding the position of Au NPs are carried out and compared with the experimental data.

A classical approach to the production of carbon aerogels by pyrolysis of organic resorcinol–formaldehyde aerogels has been studied. Organic aerogels with a density of no more than 0.17 g/cm3 and a specific surface area of up to 632 m2/g have been obtained. The corresponding carbon aerogels had a density of no more than 0.20 g/cm3, while their specific surface area reached 757 m2/g. The effect of important synthetic parameters—the concentration of the catalyst and the aging time of the precursor gel—on the features of the porous structure and the value of the specific surface area is demonstrated. For the first time, such an effect has been studied in detail for the size distribution of meso- and micropores.

A novel method for introduction of tungsten oxide nanoparticles into a Nafion membrane following the infiltration concept is presented. Non-polar supercritical carbon dioxide is used as a solvent for impregnation of tungsten metalorganic precursor into phase-separated polymer structure. Uniformly distributed 2–4 nm particles of tungsten oxides are obtained. This size coincides with the typical diameter of hydrophilic channels in Nafion. Larger crystallites and aggregates appear also but they are easily washed out of the membrane by subsequent treatment with hydrogen peroxide. The resulting composite membrane favourably combines both increased ionic selectivity and improved proton conductivity, which makes it promising for use in vanadium redox flow batteries. Tests of the composite membranes in operating vanadium redox flow battery cells show up to 5% energy efficiency increase over wide range of current densities as compared to pristine Nafion membranes.

The generation of metal nanostructures by radiation-induced reduction of copper ions in aqueous dispersions of macromolecular complexes of poly(acrylic acid) and polyvinylimidazolе has been studied in the pH range of 2.3–4.3. It was shown that an effective coordination number of Cu2+ in the complex with polymer units decreased at lower pH, which resulted in dramatic increase of the nanoparticle formation rate. As demonstrated by transmission electron microscopy, using the poly(acrylic acid)–polyvinylimidazolе–Cu2+ complexes as precursors allows one to control the nanoparticle size and promotes assembling of spatially ordered supramolecular structures. As revealed by dynamic light scattering, decreasing the medium pH leads to ripening of the poly(acrylic acid)–polyvinylimidazolе–Cu2+ particles. The obtained results provide an evidence for strong effect of the pH value on the spatial organization of nanoparticles in irradiated suspensions. In the case of less acidic medium (at pH 3), assembling of nanoparticles occurs in flabby interpolymer particles, whereas at lower pH the metal nanoparticles are produced in the templates of the perfect macromolecular nanostructures.