Head of the laboratory of chemistry for organo-mineral materials
Department of analytical chemistry Taras Shevchenko
National University of Kyiv
60 Vladimirskaya Str., Kiev Ukraine 01601
D.Sc., PhD, Corr. member of Acad. of Sci. of Ukraine
Ievgen Mazurenko, Mathieu Etienne, Rainer Ostermann, Bernd Smarsly, Oksana Tananaiko, Vladimir Zaitsev, and Alain Walcarius
Langmuir, 2011, 27 (11), pp. 71407147
The modification of platinum nanofibers by silica using the electrochemically-assisted deposition is reported here. Pt nanofibers are obtained by electrospinning and deposited on a glass substrate. The electrochemically-assisted deposition of the sol−gel material then gives the unique possibility to finely tune the silica film thickness around these nanofibers. It also allows the successful encapsulation of a biomolecule (glucose oxidase was chosen here as a model) while retaining its biological activity, as pointed out via the electrochemical monitoring of H2O2 produced upon addition of glucose in the medium. This silica−glucose oxidase composite offers the possibility of comparing systematically the influence of the deposition time on the bioelectrode response and to compare it with the particular features of the deposits. It was found that the film first grew uniformly around the nanofibers and then started to deposit between them, covering the whole sample (fibers and glass substrate), and tended to fully embed the nanofibers for prolonged deposition. The thickness of the silica film is critical for the electroactivity of the biocomposite, the best response being obtained for a silica layer thickness in the range of the fiber diameter (50 nm).
T.V. Kovalchuk, H. Sfihi, V.N. Zaitsev, J. Fraissard
Catal. Today, 2011, V. 169 (1), pp. 138-149.
A new method has been developed for preparing acid onium salts of Keggin heteropolyacids via ion exchange on amorphous silica functionalized with pyridinium and alkylimidazolium cations (SiO2Q). The interaction between HPA and the surface-grafted cations affords acid salts of HPA with intact Keggin structure. This method offers excellent dispersion of HPA on the surface and higher resistance to HPA leaching in polar media, compared to the silica-based materials. The solids are thermally stable up to 250300 °C, depending on the onium cation and anion, the most stable being the samples with immobilized H4SiW12O4 and H3PW12O40.
V. A. Khalaf, O. A. Vasilchenko, S. P. Tishchenko, E. V. Skopenko, and V. N. Zaitsev
Journal of Analytical Chemistry, 2011, Vol. 66, No. 8, pp. 695700.
The potencies of silica with attached groups of polyoxyethylated isooctyl
phenol (SiO2 TX) as an
adsorbent for the solid phase extraction (SPE)
preconcentration of bovine serum albumin (BSA) in urine are
examined.
SiO2 TX is shown to effectively extract BSA (up to 96%) as an ion associate
with cationic (at pH 8)
and anionic (at pH 1.5) surfactants. The maximal
capacity of SiO2 TX to BSA makes 33 mg/g in the presence
of
octylpyridinium bromide, 27 mg/g in the presence of cetyltrymethylammonium
bromide or sodium dode
cylsulfate with the linearity range in Henris
area up to 23 and 20 mg/g of SiO2 TX, respectively; the distri
bution
coefficients attain 1.8 × 103 mL/g. BSA is eluted quantitatively with 14 mL
of acetonitrile containing
NaOH, which makes possible the use of
adsorbent for the reaction of protein with trifluoroethanol (TFE)
before
its photometric determination by the Lowry method. The influence of
accompanying urine compo
nents is studied, i.e., urea, glucose, Na+, K+,
Mg2+, chlorides, and phosphates, on the efficiency BSA extrac
tion from
model aqueous solutions on SiO2 TX. The detection limit for BSA makes 4 mg/L
and the analytical
range, from 12 to 140 mg/L.
DOI: 10.1134/S1061934811060086
A.O. Suvorova , S.A. Alekseev, V.N. Zaitsev
Chemistry, physics and technology of surfaces 2011, 2(1), 53-60
The fragments of nonionic surfactants Triton X-100, Neonol AF9-10, and Synthanol ALM-10 were grafted on the surface of porous silicon by means of the photoinitiated reaction in presence of iodoform. The materials obtained were studied by means of FTIR spectroscopy and temperature programmed desorption mass spectrometry (TPD MS). A mechanism of thermal decomposition of grafted surfactants, consisting in multistage transformations starting from the destruction of polyoxyethylene chain, was evaluated. The hydrophobic properties and the hydrolytic stability of obtained materials were investigated. Their hydrophobicity can be defined by the nature of grafted surfactant groups and likely depends on the presence of alkyl chains, capable to be packed into the dense hydrophobic structures on the surface.
Sorption concentration of IO3- and I- on anion exchangers AV-17 and silicas modified with tertiary ammonium groups
Zui, M.F., Shvydka, L.V., Kiforuk, L.S., Alekseev, S.A., Gerda, V.I., Zaitsev, V.N.
Journal of Water Chemistry and Technology Volume 33, Issue 4, August 2011, Pages 248-254
We have studied the possibility of using new anion exchangers based on silica with covalently-immobilized trimethyl ammonium propyl and dimethyloctadecyl ammonium propyl groups for sorption concentration of trace amounts of iodine iodide ions followed by their spectrophotometric determination. Sorption properties of new anion exchangers were compared with the properties of the industrial anion exchangers
Studies of Hydrogen Sorption on Mesoporous Carbon Composite Modified with Adsorbed Palladium"
Telbiz G.M., Gerda V.I., Kobylinska N.G., Zaitsev V.M., Fraissard J.
"NATO Science for Peace and Security Series C: Environmental Security. Carbon Nanomaterials in Clean Energy Hydrogen Systems - II, Springer Science+Business Media B.V." , 2011.- V.2, - 499-508
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Head of the laboratory of chemistry for organo-mineral materials Department of analytical chemistry Taras Shevchenko
National University of Kyiv |
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| tel: +380-97-0980693, e-mail: vnzaitsev@gmail.com, http://anchem.knu.ua/ua/main_ukr.html | |
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