The use of monolithic polymeric sorbents to simulate virus-cell interactions

A simple virus-cell complementary model system can be obtained using polymer-analogous reactions of the epoxy groups of glycidyl methacrylate-ethylene glycol dimethacrylate monolithic macroporous polymeric support and of the carboxy groups of styrene-methyl methacrylate polymeric nanospheres. The effect of thus designed microenvironment on the affinity binding parameters of virus-mimicking nanoparticles with the functionalized sorbent surface is studied by high-performance monolithic disk affinity chromatography.     

Monolithic polymeric sorbents for high-performance chromatography of synthetic polymers

A number of macroporous monolithic materials based on copolymers of butyl methacrylate or lauryl methacrylate with ethylene glycol dimethacrylate is obtained via thermal free-radical polymerization. The effect of polymerization conditions on pore parameters of the synthesized sorbents is studied. Polymer stationary phases obtained for the efficient analysis of synthetic polymers are tested for the separation of a multicomponent mixture containing polystyrene samples of various molecular masses.     

Adsorption of water vapor on modified methacrylate polymeric sorbents

Adsorption of water vapor on methacrylate copolymers and terpolymers was studied. An increase in the content of the cross-linking agent gives rise to increase in the limiting adsorption of water vapor at the saturation pressure (a _s) and to decrease in the concentration of primary adsorption centers. Modification of the initial copolymer containing 60 % of 2,3-epoxypropyl methacrylate (EPMA) monomer and 40 % of cross-linking agent, ethylene dimethacrylate, with diethylenetriamine (DETA) results in an increase in thea _s value, while modification with C₁₂ and C₁₈ alkyl, benzyl, and phenyl groups gives rise to decrease in thea _s values for the copolymeric sorbents. The concentration of primary adsorption centers (a _m) increases considerably on modification of the copolymer with DETA and C₁₂ groups and decreases markedly on modification with benzyl and phenyl groups. For terpolymers, containing EPMA and styrene, an increase in the styrene/EPMA ratio reduces thea _s anda _m values. The copolymer modified with DETA groups possesses the most hydrophilic properties, while the copolymer modified with benzyl group exhibits the most hydrophobic properties. The mechanism of adsorption of water molecules on the polymers is discussed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2163–2167, November, 1995.The work was financially supported by the Russian Foundation for Basic Research (Project No. 94-03-09550).     

Strontium(II) sorption by complexing polymeric sorbents with various structures

Optimal conditions for strontium(II) sorption by new complexing polymeric sorbents (CPSs) from aqueous solutions were studied, namely, optimal solution acidity (pH_opt), pH of 50% sorption (pH₅₀), and optimal time and temperature of quantitative sorption. The strontium(II) sorption capacities of the test sorbents (SCSs) were determined, and sorption isotherms were plotted. The strontium(II) sorption parameters determined were used to recognize the most efficient CPSs.     

Thermochemical aspects of interaction of polyimide composites with organic sorbents

Interaction of ITA-31 polyimide binder with a series of industrial sorbents based on styrene and vinylpyridine derivatives was studied.     

Synthesis and properties of polymeric and organo-inorganic amphiphilic sorbents molecularly imprinted with cholesterol

Polymeric and organo-inorganic sorbents molecularly imprinted with cholesterol were synthesized to create selective hemosorbents for efferent therapy of hypercholesterlemia. These sorbents are block copolymers of 2-hydroxyethyl methacrylate and ethylene glycol dimethacrylate and granulated organo-inorganic sorbents in which the imprinting was performed in the layer of the above copolymer on the surface of selenium (Se) nanoparticles stabilized with polyvinyl pyrrolidone. The physicochemical and sorption properties of the sorbents were studied.     

Rapid analysis of proteins and peptides by reversed-phase chromatography with polymeric micropellicular sorbents

Peptides and proteins were separated by reversed-phase chromatography on a 30 x 4.6 mm I.D. column packed with non-porous crosslinked polystyrene particles having a mean particle diameter of 3 micron and a rugulose surface. The polymeric support did swell slightly in organic solvents, but the estimated 5-8% change in particle diameter did not adversely affect the efficiency of the column which was used repeatedly with gradient elution from water to organic solvent under conditions typically employed in reversed-phase chromatography. In these experiments, the pH of the eluent was varied in a wide range in order to compare the effect of acidic and alkaline eluents on the separation of protein and complex peptide mixtures. The column showed no deterioration even after extensive exposure to alkaline mobile phases. The retention behavior of sixteen proteins having widely different pI values was studied as a function of the eluent pH. The chromatographic system exhibited large selectivity differences upon changing the pH of the eluent from 2 to 11. Analytical information about peptide and protein mixtures could therefore be enhanced by using eluents at the pH extremes. At the pH extremes of 2 and 11 peak sharpness and protein mass recovery were found to be superior to those obtained with neutral eluents. Usually the column temperature was held at 80 degrees C and typical analysis times ranged from 30 s to 10 min as illustrated by chromatograms of protein mixtures and by peptide maps. With regular use under such conditions the column showed no deterioration after three months.     

Development and application of molecularly imprinted polymers as solid-phase sorbents for erythromycin extraction

Six molecularly imprinted polymers (MIPs) of erythromycin (ERY) were prepared by noncovalent bulk polymerization using methacrylic acid (MAA) as the functional monomer. On the basis of binding analysis, the MIPs with 1:2 optimum ratio of template to MAA were selected for subsequent scanning electron microscopy and Brunauer–Emmett–Teller analyses, which indicated that the MIPs had more convergent porous structures than the nonimprinted polymers. The equilibrium binding experiments showed that the binding sites of MIPs were heterogeneous, with two dissociation constants of 0.005 and 0.63 mg mL⁻¹, respectively. Furthermore, the performance of the MIPs as solid-phase extraction (SPE) sorbents was evaluated, and the selectivity analysis showed that the MIPs could recognize ERY with moderate cross-reactivity for other macrolides. The overall investigation of molecularly imprinted SPE for cleanup and enrichment of the ERY in pig muscle and tap water confirmed the feasibility of utilizing the MIPs obtained as specific SPE sorbents for ERY extraction in real samples. Figure Schematic diagram of the preparation and application of the erythromycin imprinted molecularly imprinted polymers Suquan Song and Aibo Wu contributed equally to this work.     

Mass transfer effects in preparative chromatography of eremomycin on polymeric sorbents

This work is devoted to the study of the regularities of the sorption of the new antibacterial antibiotic eremomycin on carboxylic sorbents. The main sorption kinetic equilibrium and dynamic parameters for realization of one-act preparative chromatographic process were determined and the difference between gel-like and structurally segregated carboxylic cation exchangers was analyzed. The optimal conditions for sorption and complete desorption of eremomycin were found.     

Hydrophilic hypercrosslinked polymeric sorbents for the solid-phase extraction of polar contaminants from water

Three new hypercrosslinked polymers with hydrophilic character arising from hydroxyl moieties in their skeletons have been prepared in microsphere format and applied to the off-line solid-phase extraction (SPE) of polar compounds from water samples. For sample volumes of 1000 ml, the recoveries of various polar pesticides, such as oxamyl, methomyl, selected phenolic compounds, as well as some pharmaceuticals, were close to 90%. The HXLPP-polar polymer with the best performance characteristics was applied to real samples. Its performance was also compared to commercially available sorbents, such as LiChrolut EN (hydrophobic, hypercrosslinked), Oasis HLB (hydrophilic, macroporous) and Isolute ENV+ (hydrophilic, hypercrosslinked); the new sorbent out-performed the commercially available sorbents. The polymer was applied successfully in off-line SPE of river water samples followed by liquid chromatography and ultraviolet detection, providing a good linear range and detection limits of 0.2 μg l⁻¹ for the majority of the compounds, with the exception of oxamyl, methomyl, guaiacol and salicylic acid where the detection limit was 0.5 μg l⁻¹.     

Use of theory of multimolecular adsorption at heterogenous surfaces to describe the adsorption of hydrocarbon on polymeric sorbents

Theoretical and Experimental Chemistry -     

Study of structure properties of organized silica sorbents synthesized on polymeric templates

Mesoporous silica materials were synthesized by applying Pluronic type polymers as pore creating agents. The composition of a reacting mixture and the process conditions were changed in a synthesis procedure. These changes differentiated the characteristics of porous structure of obtained sorbents. The parameters characterizing the pore structure were estimated and the changes of pore arrangement of obtained materials being a result of different synthesis conditions were investigated. The small-angle XRD results indicate that F cubic structure was formed what confirms the cage-like ordering of the synthesized silicas.     

Bi-Langmuir isotherms' applicability for description of interaction of ion-exchange sorbents with protein mixtures

The sorption of a protein pair on carboxylic cation exchangers with various contents of ionogenic groups is examined. The bi-Langmuir isotherm calculation is carried out from sorption data for single-component systems. It is shown that good agreement of calculated and experimental data is reached only when protein-sorbent interaction weakens because of implementation of the competitive sorption mechanism.     

The possible mechanism of binding interaction of insulin molecule with its receptor.

Detailed structural comparisons and investigation of DPI, 2 Zn insulin and some other derivatives of insulin were performed by the least-squares superimposition technique and the graphics technique. It is pointed out in this paper that the binding interaction with the receptor molecule should take place mainly on an amphipathic surface of the insulin molecule. In the middle, there is a hydrophobic surface with an area of about 150 A2 consisting of many hydrophobic residues; while the polar or charged groups distributing around the hydrophobic surface construct a hydrophilic zone. The hydrophobic surface is usually covered by the extended B-chain C-terminal peptides with great mobility and protected from the solvent molecules. The angle between the amphipathic surface and the surface of dimerization is about 20 degrees. The results from the detailed structural comparison between Al-(L-Trp) insulin and Al-(D-Trp) insulin have provided a very good explanation to their great difference in biological activity, and confirmed our proposed binding interaction model of the insulin molecule with its receptor as well.     

Development of principles of controlled synthesis of monolithic polymeric sorbents for ion chromatography

A series of monolithic macroporous sorbents based on glycidyl methacrylate and ethylene glycol dimethacrylate were prepared by free radical copolymerization. The effect of polymerization conditions and composition of reaction mixture on the pore structure of the monolithic material was studied by IR spectroscopy, intrusion mercury porosimetry, and scanning electron microscopy.     

A small molecule discrimination map of the antibiotic resistance kinome

Kinase-mediated resistance to antibiotics is a significant clinical challenge. These enzymes share a common protein fold characteristic of Ser/Thr/Tyr protein kinases. We screened 14 antibiotic resistance kinases against 80 chemically diverse protein kinase inhibitors to map resistance kinase chemical space. The screens identified molecules with both broad and narrow inhibition profiles, proving that protein kinase inhibitors offer privileged chemical matter with the potential to block antibiotic resistance. One example is the flavonol quercetin, which inhibited a number of resistance kinases in vitro and in vivo. This activity was rationalized by determination of the crystal structure of the aminoglycoside kinase APH(2″)-IVa in complex with quercetin and its antibiotic substrate kanamycin. Our data demonstrate that protein kinase inhibitors offer chemical scaffolds that can block antibiotic resistance, providing leads for co-drug design.     

Classical interaction model for the water molecule

The authors propose a new classical model for the water molecule. The geometry of the molecule is built on the rigid TIP5P model and has the experimental gas phase dipole moment of water created by four equal point charges. The model preserves its rigidity but the size of the charges increases or decreases following the electric field created by the rest of the molecules. The polarization is expressed by an electric field dependent nonlinear polarization function. The increasing dipole of the molecule slightly increases the size of the water molecule expressed by the oxygen-centered sigma parameter of the Lennard-Jones interaction. After refining the adjustable parameters, the authors performed Monte Carlo simulations to check the ability of the new model in the ice, liquid, and gas phases. They determined the density and internal energy of several ice polymorphs, liquid water, and gaseous water and calculated the heat capacity, the isothermal compressibility, the isobar heat expansion coefficients, and the dielectric constant of ambient water. They also determined the pair-correlation functions of ambient water and calculated the energy of the water dimer. The accuracy of theirs results was satisfactory.     

Configuration interaction calculations on the nitrogen molecule

A contracted Gaussian basis set capable of describing about 63% of the correlation energy of N₂ has been used in a detailed configuration-interaction calculation. Second-order perturbation theory overestimated the correlation energy by 23–50% depending on how H⁰ was chosen. Pair-pair interaction affects the correlation energy by about 20% while quadruple excitations have an 8% effect.