The results of long-term researches of thin films prepared from tetraethoxysilane-derived sols containing inorganic and organic additives are systematized and analyzed. These additives give to films ...certain physicochemical properties for their application in electronic techniques, optics, power engineering, in biological technologies etc. The influence both inorganic (salts, acids) and organic (polyols, polyionenes, epoxy resin) additives on rheological properties and aggregate stability of sols as well as films surface morphology is minutely considered. The explanations of phenomena during film formation, including spin-coating process, are given. Essential influence of temperature and humidity on films surface morphology is shown. Influence of heat treatment modes on structure and composition of films is analyzed. Recommendations about optimization of thin films sol–gel processing are offered.
Cytotoxic effects of a new targeted phototoxin DARPin-miniSOG and mechanism of its action were investigated in vitro. It was determined that DARPin-miniSOG causes light-induced death of ...HER2/neu-positive cancer cells (IC50 0.8 μM). Treatment of the cells with DARPin-miniSOG in the presence of ascorbic acid eliminated the light-induced cytotoxic action of the protein. This observation suggests the involvement of oxidative stress in the mechanism of the phototoxin action. DNA fragmentation analysis, caspase-3 activity assay and PI-staining of HER2/neu-positive cancer cells treated with DARPin-miniSOG indicated that phototoxin induces necrotic cell death under blue light illumination. Co-localization analysis showed that DARPin-miniSOG accumulates mostly in endosomes and lysosomes.
•Genetically encoded toxin based on HER2/neu-specific DARPin and photoactive flavoprotein miniSOG was created.•DARPin-miniSOG possesses specific cytotoxic action on HER2/neu-positive SK-BR-3 cells under illumination (IC50 0.8 μM).•HER2/neu-positive SK-BR-3 cells treated with DARPin-miniSOG undergo oxidative stress and necrosis.•Co-treatment of the cells with DARPin-miniSOG and antioxidant increases IC50 of DARPin-miniSOG in ∼9-fold.
This work is devoted to the study of the composition and structure of thin “spin-on glass” films and xerogels prepared from silica sols containing platinum and palladium compounds, both separately ...and together. The thickness and concentration distribution of Pt/Pd nanoparticles (NPs) in silica films depending on the concentration of precursors of platinum and palladium in silica sols were determined using the method of X-ray reflectometry. The composition and size of Pt/Pd nanoparticles formed in xerogels and thin films were determined in the nanometer and submicron ranges by means of atomic force and transmission electron microscopy of high resolution as well as by means of X-ray diffraction analysis. It was also determined that bimetallic Pt/Pd nanoparticles possess a common crystal lattice forming clusters with the structure of a mixed alloy type.
Highlights
Pt/Pd NPs with bimetallic crystal lattices form from TEOS-derived sols doped with Pt and Pd.
The size of Pt/Pd bimetallic NPs formed in films is 5–6 nm and of the ones formed in xerogels–10–18 nm.
A Pt and Pd concentration gradient is detected in 30–40 nm-thick doped silica films.
Pt/Pd crystallites up to 70 nm in size form at the meso level as well.
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Organomineral sorbents have been prepared by “mild” mechanical activation of air-dry clinoptilolite rocks with synthetic polymer (polyacrylamide) additions in an IVCh-3 laboratory-scale vibratory ...attritor (shear impact treatment for 3 min; specific mechanical energy delivered to the material, 2.16 kJ/g). The materials were characterized by scanning electron microscopy, infrared spectroscopy, differential scanning calorimetry, thermogravimetry, X-ray powder diffraction, and low-temperature nitrogen adsorption–desorption measurements. We have determined their specific surface area, specific pore volume, pore diameter, loose bulk and true densities, hygroscopic humidity, and oil sorption capacity. Modification of clinoptilolite rocks with 5 and 10 wt % polyacrylamide has been found to reduce the oil sorption capacity of the zeolites by 6–18%. The oil sorption capacity of the material modified with 20 wt % polyacrylamide was essentially the same as that of mechanically activated polymer-free clinoptilolite rocks.
Tetraethoxysilane-derived silica sols stable to sedimentation as well as kinetically and “sol-gel@paint” compositions based on beeswax dissolved in tetraethoxysilane with addition of ...polyorganosiloxanes, siloxane block copolymer, and hydrophobized aerosil synthesized within this study served as a base for the development of a new technique for preparation of coniferous wood protective coatings. The surface morphology of the coatings was investigated along with their chemical composition, hydrophobicity/hydrophilicity, and adhesion and water absorption. The laboratory tests for biostability with respect to wood-destroying fungi and full-scale climatic tests in the conditions of Extreme North of Russia were performed upon the pine wood coated with developed coatings and their results are presented in this study.
Highlights
New two-layer wood protective coatings based on silica sols, wax, and siloxanes were developed
A SiO
2
matrix is shown to be a film-forming basis with the wax serving only as a chemically unbound filler
All coatings developed reduced the water absorption of wood significantly (15–35% vs. 98%)
Both wax and siloxane block copolymer contribute to maintaining a high hydrophobicity level of the coatings
The solution of H
3
BO
3
in glycerin used as a modifier increases weatherability and funginertness of the coatings
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We have studied the effect of mechanical activation and modification with polyvinyl alcohol (PVA) on the composition, structure, and oil sorption capacity of zeolite (clinoptilolite and ...clinoptilolite–stilbite) rocks. The specific power of the vibratory attritor was 12 W/g, the specific mechanical energy delivered to the materials was 2.16 kJ/g, and the ball-to-powder weight ratio was 32 : 1. The materials were characterized by scanning electron microscopy, X-ray diffraction, infrared spectroscopy, differential scanning calorimetry, thermogravimetry, and low-temperature nitrogen adsorption measurements. The results demonstrate that modification of clinoptilolite–stilbite or clinoptilolite rocks with 20 wt % PVA raises their oil sorption capacity on solid surfaces by 15–18%.
Biodegradable solid-phase poly(vinyl alcohol)/carboxymethyl cellulose composites, which are promising to be used in pharmaceutics, agriculture, and chemical industry, have been obtained by an ...environmentally friendly method of “mild” mechanochemical activation without solvents and crosslinking agents. Air-dry mixtures of poly(vinyl alcohol) and carboxymethyl cellulose taken in mass ratios of 2 : 1, 1 : 1, and 1 : 2 have been subjected to a shock–shear action for 3 and 5 min (mechanical energy doses of 0.74 and 1.24 kJ/g) using an IVS-4 vibrating grinder (1500 rpm; 23.4 Hz; 0.55 kW; sample weight, 50 g; grinding bodies-to-sample mass ratio, 44 : 1). The mechanically activated samples in the form of medium powders (bulk density within a range of 600–1000 kg/m
3
) have been studied by the methods of scanning electron microscopy, differential scanning calorimetry, thermogravimetry, IR spectroscopy, optical microscopy, pycnometry, turbidimetry, and gravimetry. It has been found that the mechanochemical activation of an equimass mixture of poly(vinyl alcohol) and carboxymethyl cellulose at a mechanical energy dose of 1.24 kJ/g yields polymer solutions with a concentration of 1 g/dL that are rather transparent in the visible region (turbidity of 0.14 cm
–1
) and stable for 96 h. It has been revealed that, when being dried at 25°C, poly(vinyl alcohol) crystallizes from aqueous 1 and 2 g/dL solutions to form dendrites or crystallites after treatment at mechanical energy doses of 0.74 and 1.24 kJ/g, respectively. Polymer films of the composites have a complex morphology that includes dendritic and axialite crystalline forms. It has been found that the mechanochemical treatment stimulates the formation of crystalline forms of polymers, changes their intermolecular interaction, and affects the hydroxyl and ether groups of carboxymethyl cellulose, as well as the hydroxyl groups of poly(vinyl alcohol).
Hybrid ion-conducting membranes (HIMs) are obtained by the liquid-phase synthesis method, and the degree of their swelling in water and ionic conductivity are studied. The design of a multifactorial ...experiment by the Latin square method makes it possible to select the optimum ratio of the functional components of the HIMs. It is found that the obtained hybrid membranes are anion-conducting.
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We have studied the effect of the phase composition of clinoptilolite rocks and the specific mechanical energy delivered to samples in a vibratory attritor on their physical properties and oil ...sorption capacity. Mechanical activation in air has been shown to cause amorphization, transformation of “zeolitic” water into “hydroxyl” water, and an electron density redistribution in the Al–O–Si framework of the clinoptilolite. Milling to a specific mechanical energy of 2.16 kJ/g leads to the formation of molecularly dense aggregates, which shows up as a decrease in specific surface area, demonstrated by BET measurements. An optimal approach for raising oil sorption capacity is mechanical activation of clinoptilolite–stilbite rock in air to a specific mechanical energy of 5.04 kJ/g.
The interaction of iron oxide nanoparticles with an aqueous medium has been studied. The composition of the nanoparticles corresponds to magnetite–maghemite solid solutions with different Fe
2+
/Fe
...3+
ratios. Nanoparticles that most closely correspond to the composition of maghemite (γ-Fe
2
O
3
) have largest hydrodynamic diameters and cause a drastic decrease in the pH of the dispersion medium during the dispersion of the powders in water. Nanoparticles that have a phase composition of a solid solution corresponding to the middle of the magnetite–maghemite series are characterized by a gradual and less pronounced decrease in pH. It has been shown that dilution of aqueous suspensions obtained from preliminarily dried powders within a concentration range of 100–0.001 mg/L followed by sonication leads to a significant increase in the hydrodynamic diameter of iron oxide particles. A possible mechanism of the studied interaction of nanoparticles with the aqueous medium has been considered. This mechanism comprises the hydration of Lewis acid sites formed by iron ions and changes in the character of the dissociation of hydroxyl groups depending on the pH of a suspension. The effect of surface passivation of the studied nanopowders with oleic acid on the processes under consideration has been investigated. The results obtained make it possible to predict the aggregative stability and a number of other characteristics of the studied suspensions being diluted with water.
