E. G. Zemtsova

Formation of Micro- and Nanostructures on the Nanotitanium Surface by Chemical Etching and Deposition of Titania Films by Atomic Layer Deposition (ALD)

In this study, an integrated approach was used for the preparation of a nanotitanium-based bioactive material. The integrated approach included three methods: severe plastic deformation (SPD), chemical etching and atomic layer deposition (ALD). For the first time, it was experimentally shown that the nature of the etching medium (acidic or basic Piranha solutions) and the etching time have a significant qualitative impact on the nanotitanium surface structure both at the nano- and microscale. The etched samples were coated with crystalline biocompatible TiO2 films with a thickness of 20 nm by Atomic Layer Deposition (ALD). Comparative study of the adhesive and spreading properties of human osteoblasts MG-63 has demonstrated that presence of nano- and microscale structures and crystalline titanium oxide on the surface of nanotitanium improve bioactive properties of the material.

Pore radius fine tuning of a silica matrix (MCM-41) based on the synthesis of alumina nanolayers with different thicknesses by atomic layer deposition

The authors investigated a new approach to modify the surface of the mesoporous silica matrix MCM-41. This approach is based on manipulating the chemical composition of the porous surface layer and also on fine tuning the pore radius by applying the atomic layer deposition (ALD) technique. The synthesis of alumina nanolayers was performed on the planar and the porous matrix (MCM-41) by the ALD technique using aluminum tri-sec-butoxide and water as precursors. The authors show that one cycle on silicon, using aluminum tri-sec-butoxide and water as precursors, results in a 1–1.2 A increase in alumina nanolayer thickness. This is comparable to the increase in thickness per cycle for other precursors such as trimethylaluminum and aluminum chloride. The authors show that the synthesis of an Al2O3 nanolayer on the pore surface of the mesoporous silica matrix MCM-41 by the ALD technique results in a regular change in the porous structure of the samples. The specific porosity (ml/g) of the MCM-41 was 0.95 and tha...

Formation and mechanical properties of alumina ceramics based on Al2O3 micro- and nanoparticles

Alumina micro- and nanopowders with the particle size from 200 μm to 40 nm synthesized by the sol-gel method are studied. The particle size dependence of γ-Al2O3→α-Al2O3 phase transformation is studied by differential thermal analysis, X-ray diffraction method, and transmission electron microscopy. X-ray diffraction data show that for alumina nanoparticles γ-Al2O3→θ-Al2O3 phase transformation occurs at 900°C, and for micro-particles it occurs in the temperature range 1150–1200°C. The alumina ceramics produced of alumina nanoparticles is shown to have higher flexural strength under three-point bending than the ceramics produced of micro-particles. The obtained results demonstrate that alumina particle size reduction stabilizes the formation of α-Al2O3 at lower temperatures, due to which the grain growth rate decreases and the flexural strength of monolithic oxide ceramics increases.

Mössbauer and magneto-chemical study of solids formed by surface chemical reaction of OH-silica groups with iron diacetylacetonato chloride (C5H7O2)2FeCl

A reaction of iron(III) acetylacetonate with silica surface OH groups results in the formation of iron–organic groups on SiO2 surface. Large dimension organic ligands inhibit an interaction between iron(III) atoms. According to magnetic and Mossbauer spectroscopy data, samples with surface iron–oxygen groups differ from samples with iron–organic groups by the absence of detectable magnetic ordering.

Zero-valent Fe confined mesoporous silica nanocarriers (Fe(0) @ MCM-41) for targeting experimental orthotopic glioma in rats

Mesoporous silica nanoparticles (MSNs) impregnated with zero-valent Fe (Fe(0) @ MCM-41) represent an attractive nanocarrier system for drug delivery into tumor cells. The major goal of this work was to assess whether MSNs can penetrate the blood-brain barrier in a glioblastoma rat model. Synthesized MSNs nanomaterials were characterized by energy dispersive X-ray spectroscopy, measurements of X-ray diffraction, scanning electron microscopy and Mössbauer spectroscopy. For the detection of the MSNs by MR and for biodistribution studies MSNs were labeled with zero-valent Fe. Subsequent magnetometry and nonlinear-longitudinal-response-M2 (NLR-M2) measurements confirmed the MR negative contrast enhancement properties of the nanoparticles. After incubation of different tumor (C6 glioma, U87 glioma, K562 erythroleukemia, HeLa cervix carcinoma) and normal cells such as fibroblasts and peripheral blood mononuclear cells (PBMCs) MSNs rapidly get internalized into the cytosol. Intracellular residing MSNs result in an enhanced cytotoxicity as Fe(0) @ MCM-41 promote the reactive oxygen species production. MRI and histological studies indicated an accumulation of intravenously injected Fe(0) @ MCM-41 MSNs in orthotopic C6 glioma model. Biodistribution studies with measurements of second harmonic of magnetization demonstrated an increased and dose-dependent retention of MSNs in tumor tissues. Taken together, this study demonstrates that MSNs can enter the blood-brain barrier and accumulate in tumorous tissues.

Two-Level Micro-to-Nanoscale Hierarchical TiO2 Nanolayers on Titanium Surface

Joint replacement is being actively developed within modern orthopedics. One novel material providing fast implantation is bioactive coatings. The synthesis of targeted nanocoatings on metallic nanotitanium surface is reported in this paper. TiO2-based micro- and nanocoatings were produced by sol-gel synthesis using dip-coating technology with subsequent fast (shock) drying in hot plate mode at 400 °C. As a result of shock drying, the two-level hierarchical TiO2 nanolayer on the nanotitanium was obtained. This two-level hierarchy includes nanorelief of porous xerogel and microrelief of the micron-sized “defect” network (a crack network). The thickness of TiO2 nanolayers was controlled by repeating dip-coating process the necessary number of times after the first layer deposition. The state of the MS3T3-E1 osteoblast cell line (young cells that form bone tissue) on the two-level hierarchical surface has been studied. Particularly, adhesion character, adhesion time and morphology have been studied. The reported results may serve the starting point for the development of novel bioactive coatings for bone and teeth implants.

Features of phase transitions upon the thermal treatment of Al2O3 nanoparticles

Micro- and nanopowders of aluminum oxide with nanoparticles ranging from 200 μm to 40 nm obtained by the sol-gel technique have been investigated and the influence of their dimensions on phase transitions γ-Al2O3 → α-Al2O3 have been studied using differential thermal analysis, X-ray diffraction, and scanning electron microscopy. The data of X-ray-phase analysis show that the phase transition from γ-Al2O3 to θ-Al2O3 is typical for aluminum oxide nanoparticles at 900°C, while phase transitions from γ-Al2O3 to θ-Al2O3 are practically not observed at 900°C for microsized aluminum oxide. The transition to the form α-Al2O3 proceeds in the temperature range from 1150 to 1200°C. Generally, the results indicate that a reduction in particle sizes allows us to stabilize the formation of α-Al2O3 at lower temperatures.

Modification of the Surface Topography and Composition of Ultrafine and Coarse Grained Titanium by Chemical Etching

In this study, we present the detailed investigation of the influence of the etching medium (acidic or basic Piranha solutions) and the etching time on the morphology and surface relief of ultrafine grained (UFG) and coarse grained (CG) titanium. The surface relief and morphology have been studied by means of scanning electron microscopy (SEM), atomic force microscopy (AFM), and the spectral ellipsometry. The composition of the samples has been determined by X-ray fluorescence analysis (XRF) and X-ray Photoelectron Spectroscopy (XPS). Significant difference in the etching behavior of UFG and CG titanium has been found. UFG titanium exhibits higher etching activity independently of the etching medium. Formed structures possess higher homogeneity. The variation of the etching medium and time leads to micro-, nano-, or hierarchical micro/nanostructures on the surface. Significant difference has been found between surface composition for UFG titanium etched in basic and acidic Piranha solution. Based on the experimental data, the possible reasons and mechanisms are considered for the formation of nano- and microstructures. The prospects of etched UFG titanium as the material for implants are discussed.

Preparation and investigation of ion-conducting nanocomposite materials based on the aerosil-silver iodide system

The phase composition of samples in the aerosil-silver iodide system has been determined using X-ray diffractometry. It has been demonstrated that the sizes of crystals of the initial silver iodide, silver iodide in the initial aerosil-silver iodide powder, and silver iodide in the aerosil-silver iodide powder after heat treatment are approximately identical to each other and equal to about 55 nm. The average size and specific surface area of particles of the initial dispersed aerosil have been determined by the adsorption method (Brunauer-Emmett-Teller method). The average particle size is approximately equal to 12 nm, and the specific surface area is ∼220 m2/g. The electrical properties of ion-conducting nanocomposite materials based on the aerosil-silver iodide system have been studied by impedance spectroscopy in the temperature range 20–160°C. An increase in the silver halide content in the mixture with the aerosil leads to an increase in the electrical conductivity. The ionic component of the electrical conductivity is dominant for glasses with a high silver halide content.

Special features of structural organization and magnetic properties of quasi-one-dimensional organoiron nanostructures on a silica support

Special features of the synthesis (constructing) of highly organized quasi-one-dimensional organoiron nanostructures were considered. For the first time magnetic properties of ferromagnetic nanostructures with a specified topology based on quasi-one-dimensional organometallic structures (of “pile“ type) fixed on an inorganic matrix were studied. The presence of an uncompensated antiferromagnetism arisen on plotting organoiron groups on a silica surface was experimentally found, and the obtained data showed the study of quasi-one-dimensional organometallic nanostructures fixed on a support to be promising for the spin electronics engineering.