This essay is dedicated to the history of creation and development of the molecular layering technique (ML) which, in the modern community of non-Russian scientists, is commonly referred to as atomic layer deposition (ALD). Basic research in the field of chemical transformations of solid surfaces using the ML method in the light of the "framework" hypothesis proposed by V. B. Aleskovskii in 1952 is discussed. A number of questions raised by international scientists including those involved in the Virtual Project on the History of ALD (VPHA, 2013), and scientists from conferences in Helsinki (Finland, May 2014.), Kyoto (Japan, June 2014), and personal communications amongst peers are addressed. For the first time in English, this article provides information about V. B. Aleskovskii and S. I. Kol'tsov who are closely associated with development of the ML technique in the Soviet Union. This paper also informs the scientific community about research groups currently engaged in ML research in Russia and introduces the scientific school of "Chemistry of highly organized substances", founded and supervised by V. B. Aleskovskii.
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.
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.
An integrated approach combining severe plastic deformation (SPD), chemical etching (CE), and atomic layer deposition (ALD) was used to produce titanium implants with enhanced osseointegration. The relationship between morphology, topography, surface composition, and bioactivity of ultra-fine-grained (UFG) titanium modified by CE and ALD was studied in detail. The topography and morphology have been studied by means of atomic force microscopy, scanning electron microscopy, and the spectral ellipsometry. The composition and structure have been determined by X-ray fluorescence analysis, X-ray diffraction, and X-ray photoelectron spectroscopy. The wettability of the surfaces was examined by the contact angle measurement. The bioactivity and biocompatibility of the samples were studied in vitro and in vivo. CE of UFG titanium in basic (NH4OH/H2O2) or acidic (H2SO4/H2O2) piranha solution significantly enhances the surface roughness and leads to microstructures, nanostructures, and hierarchical micro-/nanostructures on the surfaces. In vitro results demonstrate deterioration of adhesion, proliferation, and differentiation of MC3T3-E1 osteoblasts cell for CE samples as compared to the non-treated ones. Atomic layer deposition of crystalline titanium oxide onto the CE samples increased hydrophilicity, changed the surface composition, and enhanced significantly in vitro characteristics. In vivo experiments demonstrated non-toxicity of the implants. Etching in basic piranha solution with subsequent ALD significantly improved implant osseointegration as compared with the non-modified samples.
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.
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