N. A. Ulakhovich

Impedimetric Aptasensor for Ochratoxin A Determination Based on Au Nanoparticles Stabilized with Hyper-Branched Polymer

An impedimetric aptasensor for ochratoxin A (OTA) detection has been developed on the base of a gold electrode covered with a new modifier consisting of electropolymerized Neutral Red and a mixture of Au nanoparticles suspended in the dendrimeric polymer Botlorn H30®. Thiolated aptamer specific to OTA was covalently attached to Au nanoparticles via Au-S bonding. The interaction of the aptamer with OTA induced the conformational switch of the aptamer from linear to guanine quadruplex form followed by consolidation of the surface layer and an increase of the charge transfer resistance. The aptasensor makes it possible to detect from 0.1 to 100 nM of OTA (limit of detection: 0.02 nM) in the presence of at least 50 fold excess of ochratoxin B. The applicability of the aptasensor for real sample assay was confirmed by testing spiked beer samples. The recovery of 2 nM OTA was found to be 70% for light beer and 78% for dark beer.

Synthesis of Hyperbranched Polyester Polymaleic Acids Third Generation

The third generation hyperbranched polyesterpolyol has been modified with maleic anhydride at various ratios of the polyol to the modifying agent, from 1: 6 to 1: 18. The prepared modified polyols are capable of the complex formation with copper(II), cobalt(II), and nickel(II) ions.

Electrochemical properties of crown-containing N-(thio)phosphoryl(thio)ureas and their complexes with 3d transition metals

The electrochemical behavior of crown-containing N-(thio)phosphoryl(thio)ureas and their complexes with 3d transition metals was studied by dc voltammetry on a graphite electrode in acetone. Crown-containing N-(thio)phosphoryl(thio)ureas are not reduced but are oxidized on solid electrodes in the examined range of potentials; the electrons are transferred via the (thio)urea group. Electrooxidation of macrocyclic Co(II), Ni(II), and Cu(II) complexes probably occurs via formation of M(III) complex species. Electroreduction of these metal complexes involves stepwise electron transfer, with the oxidation state of the metal atom decreasing to 0, followed by dissociation of the electrochemical reaction products.

Synthesis and properties of hyperbranched polyester polyacrylic acids and their metal complexes

New polydentate ligands based on the hyperbranched third generation polyesters containing terminal acrylic acid fragments were synthesized. The ionization and complexation parameters of new compounds in solution were estimated by spectrophotometry and pH-metric titration followed by experimental data processing using mathematical simulation by the CPESSP program. The procedure for the synthesis was proposed. The polynuclear cobalt(II), nickel(II), and copper(II) complexes with polyester polycarboxylates were synthesized.

Aminosilyl Derivatives of Hyperbranched Polyethers and Their Metal Complexes

Surface modification of nano-sized hyperbranched polymers with the fragments capable of effective complexation makes it possible to synthesize coordination compounds with practically useful properties. It was demonstrated previously that the modification is possible of non-toxic hyperbranched polyether polyols with acid fragments followed by the synthesis of the appropriate metal complexes possessing biochemical activity [1, 2]. Modification of hyperbranched polyether polyols with aminosilyl groups will provide multifunctional compounds that combine the ability to effective complex formation with the hydrogen bonding with biosubstrates. A similar approach was found very useful in creating next-generation drugs [3] and developing advanced optoelectronic systems [4]. The hyperbranched polyether polyols of the second generation were used by us as precursors of non-toxic, water-soluble polyether polyalkoxysilylamines. Modification of the terminal hydroxy groups of aminosilane was performed as follows: DOI: 10.1134/S1070363211050227

Polynuclear copper(II) complexes with polydentate nanoligands on the basis of aminoderivatives of the hyperbranched polyesters

Coordinationally active polydentate nanoplatforms on the basis of amino-modified hyperbranched polyesters containing 7 terminal amino fragments are synthesized. Synthetic procedure is developed and polynuclear Cu(II) complexes with polyesteropolyamines are prepared. Their composition and stability of the complex forms in DMSO-water solutions are evaluated. It is found that all the compounds obtained exhibit biological activity with respect to the induced asparagine proteinase of Candida albicans.

Synthesis and spectral characteristics of a hyperbranched polyester poly(phenylcarbamate)

Synthesis of new hyperbranched polymers attracts both theoretical and practical interest due to broad spectrum of their applications [1, 2]. Hyperbranched aliphatic polyesters polyols (HBPO) are widely used in the materials chemistry, in particular for the preparation of polymers for biomedical purposes and polymers with improved mechanical performance, as well as for modification of membrane properties and drug delivery control [3–5]. Modification of hyperbranched aliphatic polyesters polyols with certain organic fragments could extend the scope of their application. The nature of the terminal group modifier determines the set of useful properties, while functionalization procedure is an independent problem in the field of organic synthesis. Taking into account the above stated, we have synthesized a hyperbranched polyester polycarbamate and studied its physicochemical properties with a view to subsequent use as hybrid complexing agent. Carbamates are known as good chelators for metal ion extraction–sorption systems [6]. A combination of the hyperbranched polyester polyol scaffold with terminal carbamate fragments could give rise to a new hybrid modifier for the development of sorption systems. In this communication we describe a procedure for the synthesis of a hyperbranched polyester polycarbamate via electrophilic addition [7, 8] of phenyl isocyanate to HBPO H20 (1) containing 16 terminal hydroxy groups. The resulting hyperbranched polymer 2 contained phenylcarbamate fragments at the terminal positions. Polymer 2 was isolated as a light brown amorphous substance which was insoluble in water and diethyl ether and soluble in acetone, dioxane, tetrahydrofuran, DMSO, and DMF. The IR spectrum of 2 displayed a medium-intensity absorption band at 3319 cm due to NH stretching vibrations, amide II band (δ NH) at 1534 cm, and amide III bands (νC–N) at 1315 and 1082 cm. Stretching vibrations of aromatic and aliISSN 1070-4280, Russian Journal of Organic Chemistry, 2015, Vol. 51, No. 10, pp. 1499–1501.

Hyperbranched polyesterpolyols as components of amperometric monoamine oxidase biosensors based on electrodes modified with nanomaterials for determination of antidepressants

The use of hyperbranched polyesterpolyols of different generations favors firmer fixation of carbon nanotubes and silver nanoparticles as components of composite materials on the electrode surface (0.028 mg cm–2), which improves the operation characteristics of monoamine oxidase biosensors. The size of silver nanoparticles (18–52 nm) depends on the conditions for preparing hyperbranched polyesterpolyols, and their use as electrode modifiers influences the analytical possibilities of amperometric biosensors. Silver nanoparticles (18 nm, data of atomic force microscopy) in polyesterpolyols of third generation (pH 10.0) as components of the developed biosensors extend the interval of determinable concentrations to 1 × 10–4–1 × 10–8 M and decrease the lower limit of determination to 3 × 10–9 M, compared to the unmodified sensors, owing to enhancement of the analytical signal. The developed biosensors were tested in monitoring of drugs (antidepressants) in Coaxil and Auroriks drug forms with the relative standard deviation on the level of 0.052.

Synthesis and spectral characteristics of 2,2-bis(hydroxymethyl)propionic acid derivatives as model compounds for the estimation of properties of modified hyperbranched polyesters polyols

New amino and carboxy derivatives of methyl 2,2-bis(hydroxymethyl)propionate have been synthesized as models of terminal fragments of hyperbranched polyester polyamines and polyesters polycarboxylic acids, and their spectral characteristics have been studied.

Hyperbranched polyester poly(3-diethylamino)propionates and their copper(ii) complexes

Novel polydentate ligands were obtained from second and third generation hyperbranched polyesters containing terminal (3-diethylamino)propionate groups. Polynuclear CuII complexes with these ligands were synthesized. The degree of diethylamination of the polyesters increases when moving from the second to the third generation (from 56 to 81%). In polynuclear complexes, the ratios of Cu to hyperbranched ligand are 6 : 1 and 13 : 1 for second and third generation polyester polyamines, respectively. It was demonstrated using IR and ESR spectroscopy that each coordination polyhedron in the complexes is an isolated paramagnetic center of the formula CuN2O2Solv2 (Solv = H2O, DMSO).