Biomedical subjects

Olga Kornysova

Publications and source records attributed to Olga Kornysova.

8 recordsLinked to original sources

PubMed2006

Synthesis and evaluation of polymeric continuous bed (monolithic) reversed-phase gradient stationary phases for capillary liquid chromatography and capillary electrochromatography.

There is a demand of novel high resolution separation media for separation of complex mixtures, particularly biological samples. One of the most flexible techniques for development of new separation media currently is synthesis of the continuous bed (monolithic) stationary phases. In this study the capillary format gradient stationary phases were formed using continuous bed (monolith) polymerization in situ. Different reversed-phase stationary phase gradients were tailored and their resolution using capillary liquid chromatography and capillary electrochromatography at isocratic mobile phase conditions was evaluated. It is demonstrated, that efficiency and resolution of the gradient stationary phases can be substantially increased comparing to the common (isotropic) stationary phases. The proposed formation approach of the gradient stationary phase is reproducible and compatible with the capillary format or microchip format separations. It can be easily automated for the separation optimizations or mass production of the capillary columns or chips.

Benzene Derivatives↗

PubMed2006

Impact of pore structural parameters on column performance and resolution of reversed-phase monolithic silica columns for peptides and proteins.

In this work, monolithic silica columns with the C4, C8, and C18 chemistry and having various macropore diameters and two different mesopore diameters are studied to access the differences in the column efficiency under isocratic elution conditions and the resolution of selected peptide pairs under reversed-phase gradient elution conditions for the separation of peptides and proteins. The columns with the pore structural characteristics that provided the most efficient separations are then employed to optimize the conditions of a gradient separation of a model mixture of peptides and proteins based on surface chemistry, gradient time, volumetric flow rate, and acetonitrile concentration. Both the mesopore and macropore diameters of the monolithic column are decisive for the column efficiency. As the diameter of the through-pores decreases, the column efficiency increases. The large set of mesopores studied with a nominal diameter of approximately 25 nm provided the most efficient column performance. The efficiency of the monolithic silica columns increase with decreasing n-alkyl chain length in the sequence of C18<C8<C4. The resolution of proteins and peptides by reversed-phase gradient liquid chromatography on n-octadecyl, n-octyl, and n-butyl bonded monolithic silica columns is optimized. The results obtained imply the use of acetonitrile concentration gradient up to 75% for n-octadecyl and n-octyl bonded monolithic silica columns, and the use of acetonitrile concentration gradient up to 85% for n-butyl bonded monolithic silica columns. With the respect to the gradient times and flow rates, the optimum conditions are the best with n-octyl and n-butyl bonded monolithic silica columns, where the range of optimum gradient times is up to approximately 30 min and mobile phase flow rates in the range of 0.5-1 ml/min. Consequently, the best performance towards peak resolution is obtained with n-octyl bonded monolithic silica column with the respect to low concentration of organic phase gradient, fast separations and low solvent consumptions due to low flow rates.

Chromatography, Liquid↗

PubMed2006

Preparation of a monolithic capillary column with immobilized alpha-mannose for affinity chromatography of lectins.

A simple method for the preparation of an affinity monolithic (also called continuous bed) capillary column for alpha-mannose-specific lectins is described. 2-Hydroxyethyl methacrylate in combination with (+)-N,N -diallyltartardiamide (DATD) and piperazine diacrylamide (PDA, 1,4-bisacryloyl-piperazine) as crosslinkers, were used as monomers for the monolith. After oxidation of DATD with periodate, alpha-mannose with spacer was bound to the aldehyde groups of the polymeric skeleton via reductive amination to form an affinity column for the separation, enrichment or binding studies of mannose-specific lectins. The permeability of the column was excellent. The porosity of the monolith was investigated by scanning electron microscope (SEM) and inverse size exclusion chromatography (ISEC). The affinity of the monolith was evaluated by frontal analysis (FA) and fluorescence microscopy (FM) using fluorescently labeled concanavalin (Con A). Frontal affinity chromatography showed a specific interaction of two different lectins with the alpha-mannose-modified monolith. According to FM the affinity sites were evenly distributed over the monolithic bed.

Chromatography, Affinity↗

PubMed2006

Application of monolithic (continuous bed) chromatographic columns in phytochemical analysis.

One and a half decade passed since the pioneering work on synthesis and application of non-particulate monolithic stationary phases for liquid chromatography was published by S. Hjertén et al. [S. Hjertén, J.L. Liao, R. Zhang, J. Chromatogr. 473 (1989) 273]. This technique attracted much interest and effort of the researchers developing chromatographic methods and designing chromatographic stationary phases due to several generic qualities of the monolithic (continuous bed) technique. Advantages include: flexibility of the technique in sense of chemistries and functional compositions of the resultant stationary phases; low separation impedance (ratio of pressure drop and efficiency) of monolithic columns; compatibility with micro and nanoformat separations; low time and labour consumption and cost-efficiency. Not surprisingly, these materials attracted interest from phytochemists as plants constitute a complex matrix. However to date, not many successful studies were published in the area of monolithic materials for solving plant metabolomics problems or substituting common particulate materials with monolithic stationary phases in phytochemical analysis. This paper provides an overview.

Chromatography, Liquid↗

PubMed2004

Homogeneous reversed-phase agarose thermogels for electrochromatography.

A method for the derivatization of agarose by covalent attachment of hydrophobic ligands for reversed-phase (RP) chromatographic separation and ionic groups for generation of electroosmosis under electrochromatographic conditions in the capillaries or microfluidic channels filled with the thermogel of this agarose derivative is described. The product renders a capability of reversible thermogelation. The thermogels formed provide sufficient hydrophobicity and electroosmosis for the separations of the analytes under RP mobile-phase conditions and electric field applied. The gels may be used repeatedly without loss of resolution. They are thermally replaceable and UV transparent (providing possibility in column/in-gel detection), require no covalent attachment to the capillary inner wall (or microchip channel), and are suitable for isocratic or gradient operation in the aqueous-organic mobile phases.

Chromatography, Micellar Electrokinetic Capillary↗

PubMed2004

Continuous beds (monoliths): stationary phases for liquid chromatography formed using the hydrophobic interaction-based phase separation mechanism.

The pioneering research work published by Hjertén et al. [J. Chromatogr. 473 (1989) 273] in 1989 dealing with development and application of the continuous bed (monolithic) technique as an attractive alternative for the classical packed columns in chromatography, stimulated further investigations in this direction. The research data published since that time on the development and application of the continuous beds formed using hydrophobic interaction-based phase separation mechanism are reviewed. Some innovative species of the beds, such as polyrotaxane beds or nonparticulate restricted-access materials for direct analysis of the biological fluids in the capillary format are also discussed. Characteristic features and practical details of the continuous bed technique are revealed. Due to many advantages, the continuous bed technique became a competitor with the traditional packings in capillary or chip-based microanalysis. The importance of the continuous bed morphology on the chromatographic characteristics is shown. The applicability of modern microscopic analysis to evaluate the morphology of the continuous beds is demonstrated.

Chromatography, Liquid↗

PubMed2004

A simplified synthesis of polymeric nonparticulate stationary phases with macrocyclic antibiotic as chiral selector for capillary electrochromatography.

A simplified approach to synthesize nonparticulate (continuous or monolithic) beds with embedded vancomycin chiral selectors for capillary electrochromatography is proposed. In the present approach, N,N'-diallyltartardiamide monomer with diol functionality is used, which can be readily converted to aldehyde groups via periodate treatment. Parallel to the activation of the polymeric matrix for covalent attachment of vancomycin, the periodate treatment has shown secondary effects on the polymeric bed morphology, namely the increase of the average pore size and porosity of the skeleton. Inversed size-exclusion chromatography was applied to characterize porosimetric properties of the capillary columns before and after the periodate treatment. Electroosmotic and enantioselective properties of the nonparticulate beds synthesized are presented. The approach is of more general interest attaching different affinity groups to the polymeric matrix and/or enhancing the accessibility to the active sites, for instance, in the molecular imprinting technique.

Anti-Bacterial Agents↗

PubMed2003

Non-particulate (continuous bed or monolithic) restricted-access reversed-phase media for sample clean-up and separation by capillary-format liquid chromatography.

Restricted-access reversed-phase non-particulate (continuous bed or monolithic) stationary phases of different hydrophobicity synthesized in 100 microm i.d. fused silica capillaries have been evaluated. A specific property of restricted-access media (RAM) is that they interact with small analytes and exclude big molecules, e.g. proteins, from access to the active sites and adsorption on the surface. This dual property facilitates direct injection of biological fluids for drug or drug-metabolite analysis. Different RAM and RAM-precursor capillary columns were tested to assess the influence of chromatographic bed morphology on loadability. Inverse size-exclusion chromatography was used for investigation of pore structural properties of the capillary-format continuous beds. The data obtained were used to discuss the mechanism of separation of the biological samples using capillary columns and to propose a model for the topochemical architecture of the RAM investigated. Different morphology of the non-particulate reversed-phase precursors resulted in two types of RAM material shielded with hydrophilic polymer, classified as homogeneous or heterogeneous topochemistry stationary phases. Capillary columns were applied for chromatography of biological fluids. High resolution was obtained, without the need for column switching, when capillary columns operated in gradient conditions. Extensive evaluation of the chromatographic properties (hydrophobicity, efficiency, separation impedance, and loadability) of the non-particulate reversed-phase materials was performed before and after shielding with hydrophilic polymer to generate restricted-access properties. Minor changes of hydrophobicity, efficiency, or separation impedance were observed after the shielding.

Acetaminophen↗