修饰硅胶表面印迹牛血红蛋白及其识别性能的研究

本文选用马来酸酐修饰后的硅胶作为载体,丙烯酰胺为功能单体,N,N’-亚甲基双丙烯酰胺为交联剂,牛血红蛋白为模板分子,采用氧化还原悬浮聚合法,合成了具有选择性识别的牛血红蛋白分子印迹聚合物。并用红外光谱(IR)、扫描电子显微镜(SEM)对聚合物进行了表征,结果表明载体表面成功接枝了分子印迹聚合物薄层。同时,选择性吸附实验表明分子印迹聚合物的具有良好的识别性能,能成功的实现水溶液中牛血红蛋白的富集。     

A blood substitute from hydroxyethyl starch and hemoglobin

One method to increase the retention time of hemoglobin (Hgb) is to react it with a hydroxyethyl starch (HES) molecule. To examine this hypothesis, polymer-bound hemoglobin compounds were synthesized by the dialdehyde route. The electrophoretic mobility patterns indicate complete binding of the Hgb. Preliminary exchange-transfusion experiments in rates showed that they could survive for at least 10 h at Hct<10% when transfused with 6% HES-Hgb solutions. The retention time of the Hgb in the urine was increased to 12 h with these new polymers.     

Fluorous-phase soluble polymeric supports

Fluorous phase soluble polymer supports derived from fluoroacrylate polymers are described. N-Acryloxysuccinimide-containing fluoroacrylate polymers were readily prepared from commercially available monomers. The activated acrylates so prepared were then converted into chelating and non-chelating ligands by amidation of the N-acryloxysuccinimide active ester residues. Phosphine ligands attached to these supports were used to prepare neutral and cationic rhodium(I) hydrogenation catalysts as well as palladium(0) catalysts. Similar substitution of pendant active ester groups to form hydroxamic acid ligands for metal sequestration is also feasible. Liquid/liquid extraction readily separated, recycled and reused these polymer-bound ligands and catalysts. While fluorous phase solubility could be attained with polymers containing only heptafluorobutyryl groups, selective solubility in a fluorous phase in contact with an organic phase was only seen with fluoroacrylates that contained larger fluorinated ester groups.     

Ageing,weathering and stabilisation of polymers

The common chemical basis of thermal ageing and weathering are outlined, and the mechanisms of antioxidant action which follow from thermal and photo-oxidation are discussed. The physical behaviour of antioxidants and stabilisers in polymers is assuming increasing importance as the polymer environment becomes more aggressive, and the rationale for the development of polymer-bound antioxidants is discussed.     

Redox electrodeposition polymers: adaptation of the redox potential of polymer-bound Os complexes for bioanalytical applications

The design of polymers carrying suitable ligands for coordinating Os complexes in ligand exchange reactions against labile chloro ligands is a strategy for the synthesis of redox polymers with bound Os centers which exhibit a wide variation in their redox potential. This strategy is applied to polymers with an additional variation of the properties of the polymer backbone with respect to pH-dependent solubility, monomer composition, hydrophilicity etc. A library of Os-complex-modified electrodeposition polymers was synthesized and initially tested with respect to their electron-transfer ability in combination with enzymes such as glucose oxidase, cellobiose dehydrogenase, and PQQ-dependent glucose dehydrogenase entrapped during the pH-induced deposition process. The different polymer-bound Os complexes in a library containing 50 different redox polymers allowed the statistical evaluation of the impact of an individual ligand to the overall redox potential of an Os complex. Using a simple linear regression algorithm prediction of the redox potential of Os complexes becomes feasible. Thus, a redox polymer can now be designed to optimally interact in electron-transfer reactions with a selected enzyme.     

Molecular imprinting on amphiphilic folded polymers for selective molecular recognition in water

We report amphiphilic folded polymers with imprinted nanocavities for selective molecular recognition in water. For this, a molecular imprinting technique is applied to the polymer synthesis: amphiphilic polymer micelles interacting with template molecules are crosslinked in water to fix the folded architecture and memorize the template structure within the polymers; the removal of the templates provides imprint polymers bearing template-specific nanospaces. Here, a hydrophilic dye bearing two anionic groups, Orange G (OG), is used as a model template. For the imprinting, we design amphiphilic random copolymers bearing hydrophilic poly(ethylene glycol) (PEG) chains, hydrophobic olefin groups, and quaternary ammonium groups that can interact with the template. The copolymers were prepared by living radical polymerization and post functionalization. In the presence of OG and methyl blue (MB), the imprinted nanocavity polymers simultaneously capture both of the dyes in water. The total number of encapsulated dyes increased with increasing the number of polymer-bound quaternary ammonium groups. The selectivity of OG against MB increased with the crosslinking density, while imprint polymers encapsulated OG more efficiently than nonimprint polymers. © 2020 Wiley Periodicals, Inc. J. Polym. Sci. 2020 , 58, 215–224     

Synthesis of monomethoxypolyoxyethylene-bound haemoglobins

Monomethoxypolyoxyethylene (M?_w?5000) was chemically modified and activated in order to react with the amino-groups of human haemoglobin. The best active polymeric derivatives were obtained by substituting a carboxymethoxyl group for the hydroxyl function of the polymer and by converting the carboxyl function into a N-hydroxysuccinimide active ester. When such modified polyoxyethylene derivatives were allowed to react with haemoglobin, soluble conjugates were formed with relatively low molecular weights. Some of the polymer-bound haemoglobins exhibit good oxygen-binding properties relative to unbound haemoglobin and could be suitable for use as erythrocyte substitutes.     

Photoelectrochemistry of conducting polymers modified with electron-acceptor moieties

The photoelectrochemical behavior of two polymers of the polythiophene series containing electron-acceptor groups in the main chain was studied and compared to that of the nonmodified polymer, poly(2,2'-bithiophene), PBT. The acceptor groups were 2,2'-bipyridine and biphenyl, which are electron-deficient as compared to the bithiophene unit. All three polymers demonstrated a pronounced photovoltaic effect, which for PBT was consistent with data reported earlier. The introduction of the electron-acceptor moieties was found to significantly enhance the magnitude of the steady-state photocurrent as well as to drastically alter the dependencies of the photocurrent on the polymer film thickness and the external bias. These observations indicated that the mechanism of photocurrent generation in the modified polymers differs from that in nonmodified polymer and involves the electron transfer to the electron-acceptor moieties in the polymer main chain. The values of the external quantum efficiency were estimated in a liquid-cell arrangement to be 0.27 and 0.19% for modified and nonmodified polymers, respectively.     

Nucleosides and nucleotides. Solid-phase synthesis of oligonucleotides on an insoluble, macroporous carrier

Insoluble, macroreticular, highly cross-linked polystyrene with projecting mono-methoxytrityl chloride groups 4 was prepared and condensed with thymidine (TD ) as well as with 1-(2′-deoxy-ß-D-ribofuranosyl)-2(1H)-pyridone (II_d) to give the polymers 5 and 6 respectively, containing approximately 465 μmoles resp. 650 μmoles of bound nucleoside per gram of polymer. A standard procedure for removal of the products from the support is described. Condensation of the polymer-bound nucleosides 5 and 6 , respectively, with 3′-O-acetyl-thymidine-5′-phosphate ( 7 ) in the presence of mesitylenesulfonyl chloride (MS) and subsequent removal from the polymer yielded the dinucleoside phosphates T_d-T_d ( 9 ) and II_d-T_d ( 11 ) respectively. Condensation of the polymer 8 with 3′-O-acetyl-thymidine-5′-phosphate ( 7 ) in the presence of MS and cleavage of the polymer linkage gave the trithymidine diphosphate (T_d-T_d-T_d) ( 13 ). Phosphorylation of the polymer-bound nucleosides 5 and 6 with ß-cyanoethyl phosphate in presence of MS took place in 3′-position. Similarly the polymer-bound dinucleoside phosphates 8 and 10 gave 16 and 17 respectively.     

Enantioface differentiation by chiral polymers having (+)-5,6-exo-bornanediol moieties. II. Asymmetric reduction of prochiral ketones by chiral polymers containing (+)-5,6-exo-bornanediol derivatives

The asymmetric reduction of prochiral aromatic ketones with modified reagents prepared from sodium borohydride and carboxylic acids in the presence of both chiral polymers and relating low molecular weight compounds having (+)-5,6-exo-dihydroxybornyl derivatives was carried out. The enantioface differentiation took place effectively by raising the reaction temperature, and the highest enantiomeric excess was achieved at 10°C (24.3%) in the presence of the chiral polymers. A higher optical yield (87.8%) can be obtained in the asymmetric reduction by using the low molecular weight (+)-5,6-exo-diol compounds. The effect of the reaction temperature, solvents, and the advantages of the chiral polymer-bound reagents were also discussed.     

Coenzyme models. 32. Catalytic activity of polymer-bound thiazolium ions as estimated by flavin trapping technique

Three thiazolium-containing polymers, Th-7, Th-33, and Th-18-Py [where Th-x and Py mean x mol % thiazolium unit and pyridinium unit (54 mol %), respectively], were synthesized from partially p-chloromethylated polystyrene. The catalytic activities of these polymer catalysts in acyloin condensation of aldehydes and decarboxylation of α-keto acids were estimated kinetically by oxidative trapping of the key intermediate by flavin (flavin-trapping technique). In aqueous solution at 30°C, the catalytic activity of Th-18-Py and Th-33 in condensation of p-chlorobenzaldehyde was comparable with that of the cationic-micelle-bound thiazolium ion, whereas Th-7 and a monomeric thiazolium compound (N-benzylthiazolium bromide) scarcely exhibited any catalytic activity. The catalysis of the polymer-bound thiazolium ions was sensitively suppressed by increased ionic strength. These results suggest that the pendent thiazolium ion is activated by the relatively high charge density along the polymer chain: the cationic environment is able to facilitate dissociation of the thiazolium ion to the ylid form and deprotonation of the thiazolium-aldehyde adduct to the key intermediate.     

Macromolecular metal complexes as catalysts with improved stability

Polymer-bound tertiary amine–copper complexes and polymer-bound phosphite–rhodium complexes were studied as catalysts for oxidative coupling of phenols and hydroformylation of alkenes, respectively. The activity and stability of these catalysts could be tuned or optimized by adapting the structure of the ligands and by changing the distance between adjacent ligands along the polymer chains. The latter effect has been described in terms of strain in the intermediate chain segments in the copper complexes or enhancement of the effective local ligand concentration around the rhodium complexes. So-called immobilized homogeneous catalysts were obtained by end-grafting of both types of macromolecular catalysts on to inert and insoluble silica particles. These immobilized polymeric catalysts could easily be separated and recovered. Under proper conditions a grafted polymerbound imidazole–copper complex and a new type of polymer-bound triphenyl–phosphite–rhodium complex showed excellent stability in continuous processes.     

Effects of differences in charge and hydrophobicity of surface amino acids of hemoglobins on high-performance gel-permeation chromatography

We studied the elution properties of the carboxy and deoxy forms of hemoglobins A, S, and C in gel-permeation high-performance liquid chromatography using TSK-GEL-SW-type columns. Since these hemoglobins have the same molecular mass but different amino acids at the beta 6 position, they are ideal for studies of the effect of charge and hydrophobicity on elution patterns in high-performance gel-permeation chromatography. Although there was a linear relationship between elution volume and logarithm of molecular mass of various proteins, the elution volumes of carboxyhemoglobins were found to be slightly greater than the expected volumes calculated from the molecular mass. The elution volumes of hemoglobins increased in the order of hemoglobins F, A, C, and S in 0.1 M phosphate buffer, pH 7.4, at room temperature. The elution volume of these hemoglobins was also dependent on pH and salt concentration. These results indicate that elution of these hemoglobins was affected by the electrostatic and hydrophobic interactions between hemoglobin molecules and polar sites of silica gel (with silanol groups) of the resin matrix of TSK-G2000-SW. This study may serve as a useful reference for separation and determination of molecular masses of proteins in the native state using gel-permeation liquid chromatography.     

Thermally responsive chromatographic materials using functional polymers

Functional polymers that respond to small changes in environmental stimuli with large changes in their structure and properties are often called "intelligent" polymers. We have modified material surfaces with such polymers and used them in separation systems. Silica beads were modified with the temperature-responsive polymer poly(N-isopropylacrylamide) (PNIPAAm). PNIPAAm-grafted surfaces exhibited temperature-driven alterations of hydrophilic-hydrophobic surface-properties. Using this feature, PNIPAAm and related temperature-responsive polymers have been used to generate temperature-sensitive stationary phases for chromatographic separations. We attached several different functional polymers, including temperature- and pH-responsive polymers, to silica beads. These temperature-responsive stationary phases are useful in development of separation methods since adjusting the temperature represents an extra tool for optimizing the selectivity. Applications of thermally responsive columns for separations in the HPLC mode are demonstrated.     

Photochemical synthesis of aldehydes in the solid phase

A substituted anthraquinone (AQ), previously shown to photochemically generate benzaldehyde in methanol solution, was attached to a commercially available resin via an 11 carbon tether and an amide bond. Photolysis of the polymer-bound AQ with visible or 350 nm UV light resulted in the formation of benzaldehyde in yields of 50-55% as determined by HPLC. The phenolic positions in the polymer were then alkylated using benzyl bromide and 1-iodo-3-(4-nitrophenyl)propane in a coupling reaction with K(2)CO(3) as a base and a solution-phase proton shuttle. Photolysis of these alkylated polymers resulted in the formation of benzaldehyde (54-89%) and 3-(4-nitrophenyl)-propanal (58-67%). The yields of both aldehydes dropped considerably with subsequent realkylation and photolysis, and the polymer beads began to show signs of deterioration. This is the first time that aldehydes have been made photochemically on a solid-supported phase.     

Ligand-receptor interactions in tethered polymer layers

The binding of small proteins to ligands that are attached to the free ends of polymers tethered to a planar surface is studied using a molecular theory. The effects of changing the intrinsic binding equilibrium constant of the ligand-receptor pair, the polymer surface coverage, the polymer molecular weight, and the protein size are studied. The results are also compared with the case where ligands are directly attached to the surface without a polymer acting as a spacer. We found that within the biological range of binding constants the protein adsorption is enhanced by the presence of the polymer spacers. There is always an optimal surface coverage for which ligand-receptor binding is a maximum. This maximum increases as the binding energy and/or the polymer molecular weight increase. The presence of the maximum is due to the ability of the polymer-bound proteins to form a thick layer by dispersing the ligands in space to optimize binding and minimize lateral repulsions. The fraction of bound receptors is unity for a very small surface coverage of ligands. The very sharp decrease in the fraction of bound ligand-receptor pairs with surface coverage depends on the polymer spacer chain length. We found that the binding of proteins is reduced as the size of the protein increases. The orientation of the bound proteins can be manipulated by proper choice of the grafted layer conditions. At high polymer surface coverage the bound proteins are predominantly perpendicular to the surface, while at low surface coverage there is a more random distribution of orientations. To avoid nonspecific adsorption on the surface, we studied the case where the surface is covered by a mixture of a relatively high molecular weight polymer with a ligand attached to its free end and a low molecular weight polymer without ligand. These systems present a maximum in the binding of proteins, which is of the same magnitude as when only the long polymer-ligand is present. Moreover, when the total surface coverage in the mixed layers of polymers is high enough, nonspecific adsorption of the proteins on the surface is suppressed. The use of the presented theoretical results for the design of surface modifiers with tailored abilities for specific binding of proteins and optimal nonfouling capabilities is discussed.     

Pulse injection analysis of the binding of serum proteins to porous polymer gels modified with formyl groups

Highly porous spherical polymer gels were modified with formyl groups by a modified Friedel-Crafts reaction and the interaction of serum proteins with the modified gels were examined by pulse injection analysis. The introduction of formyl groups into the polymer greatly increases its protein-binding capacity, and the protein bound to the gel is not eluted by washing with acid, alkali or urea solution. The effects of temperature and the percentage of formyl group substitution on the binding capacity indicate that the binding process can be interpreted as initial approach of the protein to the polymer surface, caused by the hydrophobic interaction, followed by formation of a stable Schiff base between the polymer gel and the protein. Theoretical treatment of the elution behaviour of the protein from the polymer-packed column is also examined, with the assumption that there are three kinds of binding site in the polymer gel: surface, macropore and micropore regions. These polymers are shown to be useful for the removal of proteins from biological samples in clinical assays using immobilized enzymes.     

Association of poly-N-[tris(hydroxymethyl)methyl] acrylamide with a water soluble β-cyclodextrin polymer

An acrylic polymer with pendent adamantyl groups was synthesized and its properties in an aqueous solution with a β-cyclodextrin (βCD) epichlorhydrin polymer examined. Viscosity properties of precursor and modified polymers show differences at low concentrations, but not at higher concentration probably due to very important hydrogen bonds which prevent the formation of intermolecular hydrophobic bonds. The association of both complementary polymers through the inclusion of adamantyl groups is evidenced by phases separation occurrence. Phase diagrams were established at two different concentrations of polymers. We have shown a maximal association of both polymers at these two concentrations, for the same ratio βCD moles/adamantyl groups: 2.4. Salt addition favors this association and displaces the two phases zone to smaller concentrations of modified polymer. Further, 4-nitrophenol can be extracted by the concentrated phase resulting from mixture of solutions of guest and host polymers, pointing out the availability of the associated phase to trap organic molecules.     

Surface structure of polymers for biomedical applications

Biological reactions with synthetic polymers are strongly influenced by the surfaces of those materials. The surfaces are often substantially different in composition and structure from the bulk. By using contemporary surface analysis methods, we can understand polymer surfaces. The surfaces of polymers can also be modified to generate desired biological responses. These points are illustrated with examples involving polyurethanes and RF plasma-deposited films.     

Synthesis and characterization of a fire-retardant polyester: Copolymers of ethylene terephthalate and 2-carboxyethyl(phenylphosphinic) acid

This article describes the synthesis and characterization of a polymer-bound nonhalogen fire retardant (NHFR). The reactive fire retardant used in this study is 2-carboxyethyl(phenylphosphinic) acid (CEPP); the polymer is poly(ethylene terephthalate) (PET). Fire-retardant and other modifiers of polymer properties must be bound to the polymer for use in fiber, medical, and food contact applications. Copolymers containing very high levels of CEPP have been prepared. Although fire retardancy in PET is achieved at relatively low levels of CEPP, our ability to produce copolymers with high levels of phosphorous makes them very attractive as polymeric nonfugitive fire retardants for other polymers, such as polycarbonate, nylon, acrylonitrile–butadiene–styrene (ABS), poly(butylene terephthalate) (PBT), and various polymer blends. This article also describes NHFR polyester compositions containing 4,4′-biphenyl dicarboxylic acid and CEPP. It is shown that an increase in aromaticity gained by incorporating the 4,4′-biphenyl dicarboxylic acid leads to higher limiting oxygen index values. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3119–3128, 1999