A. E. Baranchikov

Lattice expansion and oxygen non-stoichiometry of nanocrystalline ceria

Generalized dependence of unit cell parameter and oxygen non-stoichiometry on the particle size of nanocrystalline ceria synthesized by a wide variety of solution-based methods was established.

ZnO formation under hydrothermal conditions from zinc hydroxide compounds with various chemical histories

The sequence of phase transformations of zinc hydroxide compounds with various chemical histories during hydrothermal (HT) treatment is studied by X-ray powder diffraction and thermal analysis (TG/DTA). ɛ-Zn(OH)2 (wulfingite) is the major intermediate in ZnO production by the HT process. The micromorphology and photocatalytic activity of ZnO powders are studied.

Planar SERS nanostructures with stochastic silver ring morphology for biosensor chips

Surface-enhanced Raman spectroscopy (SERS) of living cells has rapidly become a powerful trend in biomedical diagnostics. It is a common belief that highly ordered, artificially engineered substrates are the best future decision in this field. This paper, however, describes an alternative successful solution, a new effortless chemical approach to the design of nanostructured silver and heterometallic continuous coatings with a stochastic “coffee ring” morphology. The coatings are formed from an ultrasonic mist of aqueous diamminesilver hydroxide, free of reducing agents and nonvolatile pollutants, under mild conditions, at about 200–270 °C in air. They consist of 30–100 micrometer wide and 100–400 nm high silver rings composed, in turn, of a porous silver matrix with 10–50 nm silver grains decorating the sponge. This hierarchic structure originates from ultrasonic droplet evaporation, contact-line motion, silver(I) oxide decomposition and evolution of a growing ensemble of silver rings. The fabricated substrates are a remarkable example of a new scalable and low cost material suitable for SERS analyses of living cells. They evoke no hemolysis and reduce erythrocyte lateral mobility due to suitable “coffee ring” sizes and a tight contact with the silver nanostructure. A high SERS enhancement, characteristic of pure silver rings, made it possible to record Raman scattering spectra from submembrane hemoglobin in its natural cellular environment inside single living erythrocytes, thus making the substrates promising for various biosensor chips.

Microwave-Assisted Hydrothermal Synthesis and Photocatalytic Activity of ZnO

The effect of synthesis temperature on the morphology of fine zinc oxide powders prepared by microwave-assisted hydrothermal processing of Zn(OH)2 suspensions has been studied using x-ray diffraction and low-temperature nitrogen BET measurements. The photocatalytic activity of the powders for Methyl Orange photodegradation has been assessed as a function of synthesis temperature. The results indicate that the specific surface of ZnO powders plays a key role in determining their photocatalytic activity.

Nanocrystalline ceria based materials—Perspectives for biomedical application

Nanocrystalline ceria possesses a unique complex of physical and chemical properties making it highly bioactive material. In this review, modern data on the action of nanocrystalline ceria on cells, micro- and macroorganisms are analyzed. Special attention is paid to the analysis of the factors affecting protective properties of CeO2 with respect to the living systems.

Synthesis and thermal stability of nanocrystalline ceria sols stabilized by citric and polyacrylic acids

New methods are proposed for preparing aqueous sols of nanocrystalline ceria stabilized by citric or polyacrylic acid. Transmission electron microscopy and UV-Vis spectroscopy were used to study the stability of sols in hydrothermal treatment at temperatures in the range of 120–210°C.

Coprecipitation from aqueous solutions to prepare binary fluorides

The synthesis of binary fluoride phases, specifically nanofluorides, by coprecipitation from aqueous solutions is considered in terms of phase equilibria. Phases have been precipitated in NaF-RF3 systems (where R stands for a rare-earth element), MF2-YF3 systems (where M = Ca, Sr, Ba), BaF2-ScF3, and CaF2-BaF2 systems. In the MF2-YF3 systems, unordered metastable congruently soluble phases are precipitated instead of ordered fluorite-like phases. In the BaF2-ScF3 system, the congruently soluble compound Ba3Sc2F12 is precipitated. In the NaF-RF3 systems, incongruently soluble metastable phases with a fluorite-like structure (for R = Er, Lu, Y) and the gagarinite structure (NaGdF4) are formed. In the CaF2-BaF2 system, intermediate phases have not been formed.

Cerium fluoride nanoparticles protect cells against oxidative stress

A novel facile method of non-doped and fluorescent terbium-doped cerium fluoride stable aqueous sols synthesis is proposed. Intense green luminescence of CeF3:Tb nanoparticles can be used to visualize these nanoparticles accumulation in cells using confocal laser scanning microscopy. Cerium fluoride nanoparticles are shown for the first time to protect both organic molecules and living cells from the oxidative action of hydrogen peroxide. Both non-doped and terbium-doped CeF3 nanoparticles are shown to provide noteworthy protection to cells against the vesicular stomatitis virus.

Oxygen Nonstoichiometry of Nanocrystalline Ceria

Correlation relations between oxygen nonstoichiometry and particle size in nanocrystalline CeO2 − x are revised. The ceria unit cell parameter is shown to increase from 0.5410 to 0.5453 nm as the particle size decreases from 23 to 2.3 nm. The CeO2 − x critical particle size where cerium(IV) is completely reduced to cerium(III) is calculated as 1.1–1.3 nm.

Functionalization of aerogels by the use of pre-constructed monomers: the case of trifluoroacetylated (3-aminopropyl) triethoxysilane

A novel strategy for aerogels functionalization, based on the preliminary modification of monomers before gelation, is proposed. The strategy is illustrated by the synthesis of trifluoroacetylated (3-aminopropyl) triethoxysilane (APTES)-based aerogels. An aerogel sample prepared by cogelation of APTES with tetraethoxysilane (TEOS), followed by trifluoroacetylation of free aminogroups, had a BET-surface area of 100–180 m2 g−1, while the samples prepared by cogelation of a preliminary trifluoroacetylated monomer with TEOS had a 2–5 times larger specific surface area. Trifluoroacetylated aerogels properties showed strong dependence on the supercritical drying media.