Showing papers by "Vadim G. Kessler published in 2018"
TL;DR: It was found that a small amount of titania significantly improved the antibacterial activity of obtained nanocomposites, even without immobilization of model drug, and are highly promising candidates for potential application as antibacterial agents.
Abstract: Spherical cellulose nanocrystal-based hybrids grafted with titania nanoparticles were successfully produced for topical drug delivery. The conventional analytical filter paper was used as a precursor material for cellulose nanocrystals (CNC) production. Cellulose nanocrystals were extracted via a simple and quick two-step process based on first the complexation with Cu(II) solution in aqueous ammonia followed by acid hydrolysis with diluted H2SO4. Triclosan was selected as a model drug for complexation with titania and further introduction into the nanocellulose based composite. Obtained materials were characterized by a broad variety of microscopic, spectroscopic, and thermal analysis methods. The drug release studies showed long-term release profiles of triclosan from the titania based nanocomposite that agreed with Higuchi model. The bacterial susceptibility tests demonstrated that released triclosan retained its antibacterial activity against Escherichia coli and Staphylococcus aureus. It was found that a small amount of titania significantly improved the antibacterial activity of obtained nanocomposites, even without immobilization of model drug. Thus, the developed hybrid patches are highly promising candidates for potential application as antibacterial agents.
50 citations
TL;DR: For simultaneous water purification from both inorganic and organic pollutants, a novel multifunctional hybrid nanoadsorbent has been produced in this article, where core-shell magnetic submicro-particles with iron oxidized cores were used.
Abstract: For simultaneous water purification from both inorganic and organic pollutants, a novel multifunctional hybrid nanoadsorbent has been produced. Core–shell magnetic submicro-particles with iron oxid...
46 citations
TL;DR: In this article, the feasibility of using DTPA-functionalized microparticles for chromatographic separation of rare earth elements has been investigated for different sample concentrations, elution modes, eluent concentrations, and column temperatures.
Abstract: Silica nanoparticles and porous microparticles have been successfully functionalized with a monolayer of DTPA-derived ligands. The ligand grafting is chemically robust and does not appreciably influence the morphology or the structure of the material. The produced particles exhibit quick kinetics and high capacity for REE adsorption. The feasibility of using the DTPA-functionalized microparticles for chromatographic separation of rare earth elements has been investigated for different sample concentrations, elution modes, eluent concentrations, eluent flow rates, and column temperatures. Good separation of the La(III), Ce(III), Pr(III), Nd(III), and Dy(III) ions was achieved using HNO3 as eluent using a linear concentration gradient from 0 to 0.15 M over 55 min. The long-term performance of the functionalized column has been verified, with very little deterioration recorded over more than 50 experiments. The results of this study demonstrate the potential for using DTPA-functionalized silica particles in ...
43 citations
TL;DR: It was demonstrated that introduction of the alkyl groups into the surface layer prevents the formation of the disulfide bonds between adjacent thiol groups and proved highly effective in the removal of 50% of all metal ions and turned recyclable, opening for their sustainable use in water purification.
Abstract: The magnetite nanoparticles were functionalized with silica shells bearing mercaptopropyl (monofunctional) and mercaptopropyl-and-alkyl groups (bifunctional) by single-step sol-gel technique. The influence of synthetic conditions leading to increased amounts of active functional groups on the surface and improved capacity in the uptake of Ag(I), Cd(II), Hg(II), and Pb(II) cations was revealed. The physicochemical properties of obtained magnetic nanocomposites were investigated by FTIR, Raman, XRD, TEM, SEM, low-temperature nitrogen ad-/desorption measurements, TGA, and chemical microanalysis highlighting the efficiency of functionalization and mechanisms of the preparation procedures. The removal of the main group of heavy metal cations was studied in dependence from the pH, contact time and equilibrium concentration to analyze the complexes composition for the large scale production of improved adsorbents. It was demonstrated that introduction of the alkyl groups into the surface layer prevents the formation of the disulfide bonds between adjacent thiol groups. The obtained adsorbents were employed to treat real wastewater from Ruskov, Slovakia with concentration of Fe 319 ng/cm3, Cu 23.7 ng/cm3, Zn 36 ng/cm3, Mn 503 ng/cm3, Al 21 ng/cm3, As 34 ng/cm3, Pb 5.8 ng/cm3, Ni 35 ng/cm3, Co 4.2 ng/cm3, Cr 9.4 ng/cm3, Sb 6 ng/cm3, Cd 5 ng/cm3. These materials proved to be highly effective in the removal of 50% of all metal ions, espeсially Zn, Cd, and Pb ions from it and turned recyclable, opening for their sustainable use in water purification.
26 citations
TL;DR: It is shown that wet impregnation of ZrO2 nanoparticles with 10% and 20% Eu oxide followed by thermal anneal in air above 500 °C produces full stabilization of the tetragonal phase of ZRO2 without evidencing any phase separation.
Abstract: Here, we show that wet impregnation of ZrO2 nanoparticles with 10% and 20% Eu oxide followed by thermal anneal in air above 500 °C produces full stabilization of the tetragonal phase of ZrO2 without evidencing any phase separation. The bare ZrO2 nanoparticles were obtained using three synthetic methods: oil in water microemulsion, rapid hydrothermal, and citrate complexation methods. The homogeneity of the solid solutions was assessed using X-ray diffraction, Raman spectroscopy, high resolution transmission electron microscopy, and advanced luminescence spectroscopy. Our findings show that wet impregnation, which is a recognized method for obtaining surface doped oxides, can be successfully used for obtaining doped oxides in the bulk with good homogeneity at the atomic scale. The limits of characterization technique in detecting minor phases and the roles of dopant concentration and host structure in formation of phase stabilized solid solutions are also analyzed and discussed.
21 citations
TL;DR: Two different methods of adsorption down to the molecular level are investigated, revealing the mechanism of the coordination of different groups of REE (light, medium, heavy) with iminodiacetic acid (IDA) and showing the coexistence of both mechanisms.
Abstract: Silica (SiO2)-derived nanoadsorbents are a powerful and attractive tool for the extraction and separation of rare earth elements (REE) from many perspectives such as reusability, efficiency and minimum impact on the environment. In the present work, we investigated two different methods of adsorption down to the molecular level: (1) the mechanism of the coordination of different groups of REE (light, medium, heavy) with iminodiacetic acid (IDA) was revealed by exploiting models obtained from X-ray crystallography, explaining the selectivity of this type of ligand, and (2) the mechanism of the seeding of RE(OH)3 initiated by SiO2-based nanoadsorbents was investigated by EXAFS, both individually and in combination with mechanism (1), showing the coexistence of both mechanisms. The REE loaded nanoadsorbents possess a high magnetic susceptibility. This property was studied by magnetometry to quantify the REE adsorption efficiency and compared with the values obtained from complexometry.
17 citations
TL;DR: In this study, α-MnO2 built up of inter-grown ultra-small nanoflakes with 10 nm thickness was produced in a rapid two-step procedure starting via partial reduction in solution in basic medium subsequently followed by co-proportionation in thermal treatment demonstrating considerable chemical and thermal stability.
Abstract: Nano α-MnO2 is usually synthesized under hydrothermal conditions in acidic medium, which results in materials easily undergoing thermal reduction and offers single crystals often over 100 nm in size. In this study, α-MnO2 built up of inter-grown ultra-small nanoflakes with 10 nm thickness was produced in a rapid two-step procedure starting via partial reduction in solution in basic medium subsequently followed by co-proportionation in thermal treatment. This approach offers phase-pure α-MnO2 doped with potassium (cryptomelane type K0.25Mn8O16 structure) demonstrating considerable chemical and thermal stability. The reaction pathways leading to this new morphology and structure have been discussed. The MnO2 electrodes produced from obtained nanostructures were tested as electrodes of lithium ion batteries delivering initial discharge capacities of 968 mAh g−1 for anode (0 to 2.0 V) and 317 mAh g−1 for cathode (1.5 to 3.5 V) at 20 mA g−1 current density. At constant current of 100 mA g−1, stable cycling of anode achieving 660 mAh g−1 and 145 mAh g−1 for cathode after 200 cycles is recorded. Post diagnostic analysis of cycled electrodes confirmed the electrode materials stability and structural properties.
16 citations
TL;DR: In this paper, the authors exploited the possibility to simultaneously utilize benzene-1,3,5-triphosphonic acid (H6btp) and di-2-pyridyl ketone (py2CO) which is a major player in the field of polynuclear metal complexes.
Abstract: In our effort to develop new synthetic strategies for isolation of new phosphonate frameworks, we exploited the possibility to simultaneously utilize benzene-1,3,5-triphosphonic acid (H6btp) and di-2-pyridyl ketone (py2CO) which is a major player in the field of polynuclear metal complexes. This ligand blend in the Cu(II) chemistry afforded a two-dimensional framework comprising tetranuclear, [CuII4], secondary building units. The thorough investigation of the CuII / di-2-pyridyl ketone / benzene-1,3,5-triphosphonic acid reaction system also afforded a hydrogen bonded framework. The structure of the latter comprises the cationic [Cu{py2C(OH)2}2]2+ complex [py2C(OH)2 is the hydrate of py2CO], the dianion of benzene-1,3,5-triphosphonic acid (H4btp2-) and water solvates. The magnetic properties of the layered material were rationalized on the basis of magnetically isolated [CuII4] units dominated by antiferromagnetic interactions.
9 citations
TL;DR: A correction to this article has been published and is linked from the HTML and PDF versions of this paper.
Abstract: Author Correction : Dispersion of TiO2 nanoparticles improves burn wound healing and tissue regeneration through specific interaction with blood serum proteins
4 citations