Zdeňka Sedláková

Purification of the specific immunoglobulin G1 by immobilized metal ion affinity chromatography using nickel complexes of chelating porous and nonporous polymeric sorbents based on poly(methacrylic esters). Effect of polymer structure

Ni2+ complexes of the chelating nonporous and porous bead sorbents based on methacrylic esters crosslinked with ethylene dimethacrylate were used in isolation of the horseradish peroxidase-specific immunoglobulin IgG1 from the crude mouse ascitic fluid by immobilized metal ion affinity chromatography (IMAC). Iminodiacetic and aspartic acids were attached to porous poly(glycidyl methacrylate) beads differing in size, morphology and chemical composition. Ethylenediaminetriacetic acid and quinolin-8-ol chelating groups were attached mainly to the surface hydroxyl groups in nonporous poly(diethylene glycol methacrylate) beads through spacers. The latter sorbents exhibited better kinetic characteristics than the former but a very low IgG1 sorption capacity. In a single-step IMAC procedure, the best efficiency in the specific IgG1 purification was obtained with porous sorbents (recovery 92%, purity 73%). Differences in IMAC separations are discussed from the point of view of morphology of polymer beads as well as of the type and concentration of chelating ligands.

Polymer Brushes Interfacing Blood as a Route Toward High Performance Blood Contacting Devices

In the current study, well-defined polymer brushes are shown as an effective surface modification to resist the adhesion of whole blood and its components. Poly[oligo(ethylene glycol)methylether methacrylate] (poly(MeOEGMA)), poly(hydroxyethyl methacrylate) (poly(HEMA)), poly[N-(2-hydroxypropyl) methacrylamide] (poly(HPMA)), and poly(carboxybetaine acrylamide) (poly(CBAA)) brushes were grown by surface initiated atom transfer radical polymerization (SI-ATRP) and subsequently characterized by Fourier-transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), dynamic contact angle measurements, atomic force microscopy (AFM), and surface plasmon resonance (SPR) spectroscopy. All brushes decreased the fouling from blood plasma over 95% and prevented the adhesion of platelets, erythrocytes, and leukocytes as evidenced by SPR and SEM measurements.

Suppressing Pseudomonas aeruginosa adhesion via non-fouling polymer brushes

In the current study, well-defined polymer brushes are shown as an effective surface modification to resist biofilm formation from opportunistic pathogens. Poly[oligo(ethylene glycol)methyl ether methacrylate] (poly(MeOEGMA)) and poly[N-(2-hydroxypropyl)methacrylamide] (poly(HPMA)) brushes were grown by surface initiated atom transfer radical polymerization (SI-ATRP) and subsequently characterized by Fourier-transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and dynamic water contact angle measurements. Their remarkable resistance to protein fouling after long term contact with biological media was evidenced by surface plasmon resonance spectroscopy. Challenging these brushes with an environmental strain of Pseudomonas aeruginosa in mineral media as well as a casein–soja–pepton–agar (CASO) medium resulted in no biofilm formation, while a decrease of the biofilm formation by 70% (poly(HPMA)) and 90% (poly(MeOEGMA)) was observed when the medium was rich in nutrients and proteins (fetal bovine serum). In contrast to the antibiotic sensitive strains, biofilm formation was observed using an antibiotic multi-resistant P. aeruginosa strain on both brushes. Protein fouling was fully prevented on both types of brushes, which might challenge the proposed mechanism of biofilm formation mediated by a pre-formed conditioning film of proteins. The resistance to biofilm formation and the possibility to precisely control their growth and functionalities makes these brushes ((poly(HPMA) and (poly(MeOEGMA)) promising candidates for surface modification of various biomaterials as well as platforms for basic studies into the mechanisms of bacteria fouling.

Grafting of functional methacrylate polymer brushes by photoinduced SET-LRP

Photoinduced surface-initiated single electron transfer living radical polymerization (SET-LRP) is a versatile technique for the preparation of polymer brushes. The vast diversity of compatible functional groups, together with a high end-group fidelity that enables precise control of the architecture, makes this approach an effective tool for tuning the properties of surfaces. We report the application of photoinduced SET-LRP for the surface-initiated grafting of polymer brushes from a wide range of methacrylate monomers for the first time. The living character of the process was demonstrated by the linear evolution of the polymer brush thickness in time, the ability to reinitiate the polymerization for the preparation of well-defined block copolymers, and also by X-ray photoelectron spectroscopy depth profiling. The surface patterning with these brushes could be achieved simply by restricting the irradiated area. The ability of poly(methacrylate) brushes prepared in this way to prevent non-specific protein adsorption is also demonstrated, indicating the suitability of this procedure for advanced applications.

Formation, structure, thermal and dynamic mechanical behaviour of ordered polyurethane networks based on mesogenic diol

Abstract Dynamic mechanical and thermal behaviour of ordered linear and crosslinked polyurethane systems based on a mesogenic diol, 4,4′-bis(11-hydroxyundecyloxy)biphenyl (D), 2(4)-methyl-1,3-phenylene diisocyanate (DI) and poly(oxypropylene)triol (T) was investigated during network formation and in fully cured samples. The networks were prepared at various stoichiometric initial molar ratios of the reactive groups, [OH]T/[NCO]DI/[OH]D ranging from 1/1/0 to 1/12/11; for comparison, linear sample with the ratio 0/1/1 was also investigated. From our measurements it followed: (a) The power-law parameters, which are characteristic of the critical structure at the gel point (the gel strength S and relaxation exponent n), are dependent on the initial ratio of the reactive groups. With increasing content of mesogenic diol in network chain (increasing length of elastically active network chain (EANC)) both, the gel strength S and relaxation exponent n decrease. (b) Introduction of chemical junctions reduces flexibility of the EANCs in fully cured networks and inhibits conformational rearrangements required for ordering. Increasing the content of mesogenic diol in EANCs increases the concentration of permanent physical interactions (trapped entanglements) in the systems and the intensity of the slow relaxation process in the rubbery region.

Phase transition in swollen gels: 25. Effect of the anionic comonomer concentration on the first-order phase transition of poly(1-vinyl-2-pyrrolidone) hydrogels

Abstract The swelling and mechanical behavior of ionized networks prepared by radiation polymerization of 1-vinyl-2-pyrrolidone, sodium itaconate and of a crosslinker, 3,3′-ethylidenebis(1-vinyl-2-pyrrolidone), was investigated in water/acetone mixtures and aqueous NaCl solutions. In the molar fraction range of the ionic comonomer xs=0.022–0.15, the first-order phase transition (collapse) was found. The extent of the collapse (stepwise change in the gel volume) and the critical acetone concentration in the mixture at collapse slightly increase with increasing xs. The collapse is accompanied by a stepwise change in equilibrium modulus. The expected decrease in the swelling and increase in the modulus with increasing concentration of NaCl in aqueous solutions were found. The earlier suggested theory describing the swelling equilibrium of polyelectrolyte networks was applied to description of the collapse phenomenon in water/acetone mixtures and swelling in dependence on NaCl concentration; satisfactory agreement was obtained when an effective degree of ionization i (i

Thermal and dynamic mechanical behavior of polyurethanes based on diisocyanates and diethanolamine derivatives with mesogenic groups in side chain

Abstract Thermotropic polyurethanes were prepared from three commercial diisocyanates of various flexibility and eight diols (based on diethanolamine derivatives) with mesogenic groups in side chain with stoichiometric ratio of reactive isocyanate and hydroxy groups. Polymers were studied by dynamic mechanical spectroscopy, X-ray scattering, differential scanning calorimetry and polarizing microscopy. The effect of structure changes in the diisocyanates and diols, in particular changes in the end substituents bound to the mesogen, were investigated. Introduction of mesogenic diols into the polymers suppresses the occurrence of mesophases in comparison with neat diols; in the case of simple end substituents (such as hydrogen, nitro and nitrile), the mesophases disappear completely regardless of the structure of diisocyanate. Stiff end substituents (phenyl and alkoxy groups) stabilize the mesophases to such an extent that the negative influence of long polymer chains is compensated and the liquid–crystalline (LC) properties are recovered. Generally, the polymers prepared from the stiffest 2(4)-methyl-1,3-phenylene diisocyanate exhibit a most pronounced LC behavior.

Nanocomposite preparation via in situ polymerization of quaternary ammonium salt ion-bonded to graphite platelets

Here we report a novel method of intercalation of a quaternary ammonium salt bearing a polymerizable group in between graphite galleries. By the exfoliation of the intercalate during its subsequent polymerization with n-butyl methacrylate, a polymer membrane with homogenously dispersed graphene nanostructures was obtained.

Mesogenic polybutadiene diols with thiol side-chain units: synthesis and thermal behaviour

Several types of the chiral thiols with two aromatic rings have been synthesised and grafted on polybutadiene diols backbone. The resulting functional polymers possess the OH end groups for the possible preparation of liquid crystal ordered networks. The thermal and mesomorphic properties of the synthesised side-chain units and resulting polymers have been studied by polarising optical microscopy, differential scanning calorimetry and X-ray scattering. Some of the resulting polymers possess a mesomorphic behaviour. The effects of the side-chain structure, number of the chiral groups and density of grafting on the polybutadiene diols have been studied.

Dynamic Mechanical Behavior of Ordered Off-Stoichiometric Polyurethane Systems at the Gel Point Threshold

Dynamic mechanical and thermal behavior of ordered off-stoichiometric polyurethane (PU) systems, before and after the gel point, based on the mesogenic diol 6,6′;-[ethylenebis(1,4-phenyleneoxy)]dihexan-1-ol (D),2(4)-methyl-1,3-phenylene diisocyanate (DI), and poly(oxypropylene)triol (T) were studied. Polymer samples were prepared at various initial molar ratios of the reactive groups, r = [OH]T/[NCO]DI/[OH]D, ranging from 1/10/9 to 5/10/9 (the ratio [NCO]DI/[OH]D = 10/9 was constant); the total mole ratio of hydroxy (OH) and isocyanate (NCO) groups, rOH = [OH]/[NCO] = ([OH]D)/[NCO]DI,changed from 1 to 1.4. Dynamic mechanical measurements during the curing reaction showed that the power law parameters that characterize the critical gel state (gel strength S and relaxation exponent n) are dependent on the initial composition (the ratio r OH). The gel-point critical ratio of reactive groups rc OH, found during curing in the ordered state of the diol (at low curing temperature), has revealed that the critical gel (CG) structure is determined by a contribution of strong physical interactions as well as chemical junctions and does not correspond to pure chemical gelation (CG structure formed at low temperature exhibits flow at elevated temperatures in the isotropic state). This fact suggests that formation of the mesophase enhances the connectivity of the molecular structure at the gel point. Dynamic mechanical behavior of fully cured chemical networks (r OH < r OH c ) and un-cross-linked (r OH > r OH c ) samples (and a CG sample) has also been investigated. Decreasing the rOH ratio (increasing concentration of chemical cross-links in the systems) inhibits conformational rearrangements required for ordering; at the same time, the intensity of the slow relaxation process in the rubbery region decreases.