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Poly(vinyl alcohol) core coated with poly(2-acrylamido-2-methyl-1-propanesulfonic acid-co-N-isopropylacrylamide) shell to produce well-define PVA@P(AMPS-co-NIPAm) core shell nanogels with a core of 25 ± 0.5 nm and shell of 5 ± 0.5 nm. The synthetic approach was produced by a surfactant free emulsion polymerization (SFEP). The specific area was found to be 1685.8 m2/g. The nanogels were studied in a batch adsorption for removal of Pb(II) ions and characterized by SEM, TEM, TGA and BET measurements. The results showed that the adsorption equilibrium data fitted the Langmuir isotherm and the kinetic studies are well described by the pseudo-second-order kinetic model. The Pb(II) maximum adsorption was 510.2 (mg/g) for PVA@P(90AMPS-co-10NIPAm) (wt.: wt%). The PVA@P(AMPS-co-NIPAm) nanogels were applied for extracting of Pb(II) in real different environmental water samples successfully with high recoveries reaches 104.4%.

Core shell-structured poly(vinyl alcohol) @ poly(2-acrylamido-2-methyl-1-propane-sulfonic acid-co-N-isopropylacrylamide) PVA@P(AMPS-co-NIPAm) spheres are synthesized. The well-defined PVA@P(AMPS-co-NIPAm) core shell nanogels with diameter nearly 30 nm enriches Fe(III), and the nanogels are characterized by FT-IR, TEM, SEM and X-ray diffraction (XRD). The many factors affecting adsorption were successfully investigated. The maximum capacity of Fe(III) ions was 320 (mg/g) for PVA@P(90AMPS-co-10NIPAm) (wt.: wt%). The equilibrium data matching well with the Langmuir model and the pseudo-second-order form described the adsorption process better than the pseudo-first-order model. Findings of the present study highlight using a simple synthesis of PVA@P(AMPS-co-NIPAm) nanogels as superior and recyclable nanoadsorbents.

Poly (vinyl alcohol) (PVA) nanoparticle core and poly (acrylamide-co-N-isopropylacrylamide) P(AAm-co-NIPAm) hydrogel shell were fabricated to produce well-defined PVA/P(AAm-co-NIPAm) core–shell nanogels using Surfactant Free Emulsion Polymerization (SFEP). The nanogel was characterized by the FTIR, TEM TGA thermogram and SEM techniques. The adsorbent was utilized for Cu2+ removal from aqueous solution. Batch adsorption process indicated that 0.9 mol% PAAm nanogel exhibited higher adsorption affinity toward Cu2+. The kinetics parameters were investigated according to the pseudo-first-order, pseudo-second-order and intraparticle diffusion rate models. The adsorption equilibrium match with Langmuir adsorption isotherm rather than Freundlich isotherm. The Cu2+ loaded nanogels were effectively desorbed using 0.1 mol/l from HCl as stripping agent.

Polyvinyl acetate nanocomposites were successfully prepared based on silver nanoparticles. First, silver nanoparticles were directly prepared during the in situ emulsion polymerization of vinyl ace...

Article History Tea is the second most popular drink in the world after water, and many studies have highlighted the effects of drinking tea. Therefore, the aim of this study was to explore the effects of white tea extract on the antioxidant enzymes activity including superoxide dismutase (SOD), glutathione peroxidase (GSH-px), and catalase (CAT). A significant decrease was observed in serum and liver SOD, GSH-px, and CAT activities in the diabetic control rats compared with the nondiabetic control ones. However, a significant increase in SOD, GSH-px, and CAT activities (serum and liver) was observed in the diabetic groups treated with white tea extract or Glibenclamide as compared to the diabetic control group. In conclusion, the present findings indicated that white tea extract has an enhancing effect on the antioxidant enzyme activities (SOD, CAT, and GSH-px) in STZ-induced diabetic rats.

This study aimed to investigate the biochemical influence of broccoli and beet extracts on selected individual additives NaNO2 or sunset yellow treated rats, in addition to the gene expression of some antioxidant enzymes. Forty-two male rats were assigned to seven groups of six rats in each group. The control group was fed a diet without an additive for four weeks. Group (2) received NaNO2, groups (3) received NaNO2 co-administered with broccoli extract (4) NaNO2 co-administered with beet extracts, Group (5) received sunset yellow, Group (6) received sunset yellow co-administered with broccoli extract, and Group (7) received sunset yellow co-administered with beet extract, for four weeks. At the end of the experiment, blood, liver, kidney, and brain samples were taken for biochemical and/or molecular analysis. The mRNA expression of antioxidant enzymes was determined by reversing transcriptase-polymerase chain reaction (RT-PCR). The obtained results revealed that rats co-administered with beet or broccoli extracts had a significant decrease in serum levels of AST, ALT, ALP, urea, total lipids, and triglycerides, as well as a significant increase in reduced glutathione (GSH), glutathione peroxidase (GSH-px), and superoxide dismutase (SOD) enzyme activities, compared to the normal control group. Oral administration of NaNO2 or sunset yellow caused a significant increase in serum levels of AST, ALT, ALP, urea, total lipids, and triglycerides, as well as a significant decrease in GSH, GSH-px, and SOD compared to the positive group. In conclusion, this study showed that broccoli and beet extracts have a protective effect against NaNO2 or sunset yellow in rat treated groups.

Surface display technology can be defined as that phenotype (protein or peptide) which is linked to a genotype (DNA or RNA) through an appropriate anchoring motif. A bacterial surface display system is based on expressing recombinant proteins fused to sorting signals (anchoring motifs) that direct their incorporation on the cell surface.

An enantioselective l -aspartic acid imprinted chitosan (LAIC) was prepared by cross-linking of chitosan by glyoxal cross-linker, in the presence of l -aspartic acid as an imprinted template molecule and 1% acetic acid solution as a solvent. Non-imprinted cross-linked chitosan (NIC) as control was also prepared by the same procedure in the absence of template molecules. The surface morphology of both LAIC and NIC was examined by scanning electron microscope (SEM). LAIC particles were applied to determine the optimum operational condition for l -aspartic acid separation from dilute aqueous solution. In adsorption step, optimum pH and retention time were 5 and 90 min, while corresponding values in extraction step were 2 and 50 min, respectively. Also, the adsorption isotherms indicated that the maximum adsorption capacities of l- and d -aspartic acid on LAIC were 48 ± 0.7 and 27 ± 1 mg g−1, respectively, while in the case of NIC, both l - and d -aspartic acid present the same maximum adsorption capacity 9 ± 0.8 mg g−1, which confirms that the molecular imprinting technique creates an enantioselectivity of LAIC toward l -aspartic acid. In addition, chiral resolution of l , d -aspartic acid racemic mixture was carried out using column of LAIC.

Background: The oral delivery of proteins and peptide drugs is considered a major challenge. These types of therapeutics are readily degraded, if taken orally, due to the harsh high acidity of stomach and enzymatic attack in the upper small intestinal tract. Methods: Water-soluble copolymers of sodium acrylate (AAs) grafted onto carboxymethyl cellulose (CMC) were prepared and characterized using Fourier transform spectroscopy, differential scanning calorimetry, and X-ray diffraction. The obtained graft copolymers were then used in a combination with sodium alginate to develop a new series of pH-sensitive interpenetrating polymeric network (IPN) hydrogels through ionotropic gelation with divalent ions (Ca 2+ ). Morphology of the developed hydrogels was investigated using SEM. Swelling characteristics, at distinct compositions, were also studied at 37°C in two consecutive buffer solutions of pH 2.1 and 7.4 (similar to that of gastric and intestinal fluids, respectively). The release profiles of bovine serum albumin, as a model protein, from test IPN hydrogel films were studied in simulated gastric and intestinal fluids. In addition, the drug release process was confirmed by means of SEM. Results: Swelling studies of the developed IPN hydrogels at different pH values confirmed their pH-sensitive nature. The equilibrium swelling extents of the hydrogels were found to be dependent on the grafting yield of CMC/AAs graft copolymer. The IPN hydrogels attained equilibrium swelling percentages in the range 445–740%. In addition, the amount of bovine serum albumin released within 2 hours in pH 2.1 was relatively low (less than 18.1%). This amount increased up to 68% after 8 hours in pH 7.4. Conclusions: From the obtained preliminary data, it seems that the IPN hydrogels developed in this contribution can be tailored to act as good potential carriers for oral delivery of protein drugs. These hydrogels showed a promising protection of protein drugs from the harsh acidity of stomach and, at the same time, they conferred sustained drug release in the intestinal fluid.

The graft copolymerization of ethyl acrylate (EA) onto natural wool fibers initiated by potassium persulphate and Mohr's salt redox initiator system in limited aqueous medium was carried out in heterogeneous media. Ester groups of the grafted copolymers were partially converted into hydrazide function groups followed by hydrazone formation through reaction with isatin. Also the application of the modified fibers for metal ion uptake was studied using Cu(II), Hg(II) and Ni(II). The modified chelating fibers were characterized using FTIR spectroscopy, SEM and X-ray diffraction.

Using an EDC/NHS conjugation method, chitosan was chemically modified to incorporate a photosensitive α-cyano-4-hydroxycinnamic acid moiety with various degrees of substitutions. The chitosan α-cyano-4-hydroxycinnamate was fully characterized by FTIR, 1 H NMR and UV–vis spectra. Lipase from Candida rugosa was entrapped in the modified photo-crosslinkable chitosan membranes. Crosslinking was carried out by irradiation in the ultraviolet region. The activities of free and immobilized lipase have been studied. The efficiency of the immobilization was evaluated by examining the relative enzymatic activity of free enzyme before and after the immobilization of lipase. The obtained values were found to reach 98.6%. The results showed that the optimum temperature of immobilized lipase was 40 °C, which was identical to that of the free enzyme, and the immobilized lipase exhibited a higher relative activity than that of free lipase over 40 °C. The optimal pH for immobilized lipase was 8.0, which was higher than that of the free lipase (pH 7.5), and the immobilization resulted in stabilization of enzyme over a broader pH range. The kinetic constant value ( K m ) of immobilized lipase was 1.332 mg ml −1 (1.50 × 10 −3 M), which was higher than that of free lipase. On the other hand, the activity of immobilized lipase decreased slowly against time when compared to that of the free lipase, and could retain 75.5% residual activity after 6 consecutive cycles.

A method has been developed to immobilize horseradish peroxidase (HRP) on modified chitosan beads by means of graft copolymerization of polyethylacrylate in presence of potassium persulphate and Mohr's salt redox initiator. The activity of free and immobilized HRP was studied. FTIR spectroscopy and scanning electron microscopy were used to characterize HRP immobilization. The efficiency of the immobilization was investigated by examining the relative enzymatic activity of free enzyme before and after the HRP immobilization. The obtained values were found to reach 98.4%. The results show that the optimum temperature of immobilized HRP was 45 degrees C, which was identical to that of free enzyme, and the immobilized HRP exhibited a higher relative activity than that of free HRP over 45 degrees C. The optimal pH for immobilized HRP was 10, which was higher than that of the free HRP (pH 9.0), and the immobilization resulted in stabilization of enzyme over a broader pH range. The apparent kinetic constant value (K(m)) of immobilized HRP was 3.784 mmol ml(-1), which was higher than that of free HRP. On the other hand, the activity of immobilized HRP decreased slowly against time when compared to that of the free HRP, and could retain 65.8% residual activity after 6 consecutive cycles.

In order to develop a non toxic and biocompatible hydrogel system with potential ability in biotechnology, modified photo-crosslinkable hydrogel membranes based on chitosan were prepared. Using an EDC/NHS conjugation method, chitosan was chemically modified to incorporate a photosensitive α-cyano-4-hydroxycinnamic acid moiety with various degrees of substitutions. Fourier transform infrared spectra (FTIR), proton nuclear magnetic resonance (1H NMR) and ultraviolet–visible light spectra (UV–vis) were used for structural characterization of modified chitosan, The obtained membranes were crosslinked by irradiation in the ultraviolet region, where the photosensitive monomers showed maximum sensitivity. The prepared photo-crosslinked hydrogel membranes were investigated by thermal gravimetric analysis (TGA) and wide angle X-ray diffraction (WAXD). The swelling behaviors were investigated in terms of pH, time of swelling, and degree of substitution. Also, mechanical properties of the different photo-crosslinked hydrogel membranes were studied in both dry and wet conditions.

A method has been developed to immobilize lipase from Candida rugosa on modified natural wool fibers by means of graft copolymerization of poly ethylacrylate in presence of potassium persulphate and Mohr’s salt redox initiator. The activities of free and immobilized lipase have been studied. FTIR spectroscopy, scanning electron microscopy, and the Bradford method were used to characterize lipase immobilization. The efficiency of the immobilization was evaluated by examining the relative enzymatic activity of free enzyme before and after the immobilization of lipase. The results showed that the optimum temperature of immobilized lipase was 40 °C, which was identical to that of the free enzyme, and the immobilized lipase exhibited a higher relative activity than that of free lipase over 40 °C. The optimal pH for immobilized lipase was 8.0, which was higher than that of the free lipase (pH 7.5), and the immobilization resulted in stabilization of enzyme over a broader pH range. The kinetic constant value (km) of immobilized lipase was higher than that of the free lipase. However, the thermal and operational stabilities of immobilized lipase have been improved greatly.

Chitin was extracted from shrimp shell waste and its heterogeneous alkaline deacetylation under phase transfer catalysis (PTC) condition was performed. The reaction followed the first-order kinetics during an initial period. The influences of type and concentration of phase transfer catalyst, type of organic solvent, alkaline concentration, temperature, time and volume of organic phase to the volume of aqueous phase ratio on the N -deacetylation were investigated. The degree of deacetylation (DD) increased mainly with increasing temperature, catalyst concentration and time. In the temperature range of 30–100 °C, the apparent rate constant and the activation energy of the reaction were evaluated in presence and in absence of PTC condition.

Core-shell nanogels adsorbent were investigated for copper (II) removal from aqueous solution, consisting of poly(vinyl alcohol) (PVA) core and poly(acrylamide- N-isopropylacrylamide/) p(AAm-NIPAm) shell particles. Various factors affecting the adsorption capacity, such as swelling, pH, time, initial ion concentration, and different metal ions on the metal ion binding capacity for nanogel, was also tested. The selectivity of the nanogels toward the different metal ions tested was Cu2+> Ni2+ > Pb2+. The results show that the adsorption of nanogels mainly depends on pH, and the maximum adsorption was obtained at a pH of 6.0. The adsorption capacity of Cu+2 was 126 mg/g obtained under simple and fast experimental conditions, the effect of different mole ratios of p(AAm-NIPAm) shells thickness were synthesized, to determine the maximum metal uptake. The core-shell nanogels were characterized by fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and transmission electron microscope (TEM). It was found that adsorbed Cu+2 ions on PVA/p(AAm-NIPAm) nanogels can be effectively desorbed by acid stripping with 0.1 mol/L HCl resulted in 96% Cu+2 recovery for the nanogels; this shows the ability of the nanogels to be reused, upon drying between treatments. The nanogels adsorbent can be regenerated after releasing of Cu+2 and reused three times effectively. All the experimental result exhibited good matches with the Freundlich isotherm and followed pseudo-second-order kinetics. The mechanism of adsorption of Cu+2 onto PVA/p(AAm-NIPAm) nanogels is proposed.

Synthesis and Evaluation of 2-Acrylamido-2-Methyl-1- Propane Sulfonic Acid Based on Core-Shell Nanogels for Preconcentration of Fe (III) Ions from Aqueous Solutions and their Determination in Real Water Samples In the present study, poly(2-acrylamido-2-methyl-1-propanesulfonic acid -co-N-isopropylacrylamide) hydrogels, were synthesized by free- radical crosslinking solution polymerization with different ratios of monomers to form colloidal hydrogels shell around poly(vinyl alcohol) core through epichlorohydrine, in order to obtain well-define PVA(AMPS-NIPAm) core/shell nanogels with diameter nearly 30 nm. The prepared nanogels were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Transmission electron microscopy (TEM) and Scanning electron microscopy (SEM). These Nanogels were used effectively for removal of Fe(III) ions from aqueous solutions. The factors affecting adsorption such as pH, contact time, initial concentration, temperature, ionic strength, desorption, interfering ions, and analytical application for real water samples were succefully investigated. The maximum capacity of Fe(III) ions was 320, 202 and 98 (mg/g) for PVA/p(90AMPS-10NIPAm), PVA/ p(50AMPS-50NIPAm) and PVA/p(10AMPS-90NIPAm), (wt.:wt. %), respectively. The adsorption isotherms and kinetics were determined; the equilibrium data matched well with the Langmuir model. The pseudo second-order model described the adsorption process better than the pseudo first-order model. Thermodynamic parameters revealed that a spontaneous and exothermic nature is identified in all cases of adsorption process.

Chloromethylated polystyrene was reacted with vanillin under phase transfer catalyzed conditions. This reaction was performed under different conditions, including variations of the phase transfer catalysts, the reaction solvent, the type of base, the reaction time and temperature. In addition, the effect of the reaction technique (i.e., solid–liquid–liquid and solid–liquid–solid systems) on the reaction conversion was studied. Polymer-supported vanillin was evaluated for its utilization in polymer analogue conversions by performing condensation reactions of the aldehyde functionality with malononitrile, ethyl cyanoacetate, cyanoacetamide, cyanothioacetamide, 2-aminophenol, hydrazine hydrate and hydroxylamine hydrochloride. In all cases, the reactions were followed up by means of FTIR spectroscopic analysis.

The present work studied factors which may affect phase transfer-catalyzed (PTC) nucleophilic displacement reactions, including chloromethylated polystyrene as polymer-supported alkylating agent and 4-hydroxybenzaldehyde as an O-nucleophilic reagent in presence of representatives for phase transfer catalysts. Some polymer-analogue conversions using the resulting polymer-supported aldehyde have been carried out.

The behavior of polymer-supported ambident anions derived from indane-1,3-dione towards alkylation under various conditions has been studied. Particularly, factors that may affect the yields of isolated products and their compositions have been considered. Almost exclusively the di- C -alkylation product could be isolated after relatively long reaction time. This unusual tendency toward di- C -alkylation is extensively discussed on the basis of the effect of reduced reaction time on the composition of resulting products in addition to a comparative study of mono- C -versus di- C -alkylation in indane-1,3-dione with the acyclic analogous dibenzoylmethane.

Photoinduced graft copolymerization of acrylamide (AM) onto two types of acrylonitrile-butadiene-styrene (ABS) copolymers was extensively investigated in homogeneous media. The grafting process was conducted in chloroform in presence of 4-acetyldi-phenyl (4-AD). Ultraviolet (UV) irradiation was used in the range of 310 to 460 nm. The UV spectrum of 4-AD has sλmax at 285 nm and shows n-π∗ transitions. The grafting parameters, such as weight conversion, grafting percentage, and grafting efficiency, were determined as a function of the irradiation time and the concentrations of monomer, initiator, and substrate. A reverse effect was observed between the grafting percentage and the butadiene content in ABS copolymers. The rates of graft copolymerization of AM onto the two types of ABS copolymers were determined. A Trommsdorf effect was observed in certain systems. The IR spectrum of ABS-g-AM graft copolymer shows the appearance of a new peak at 1685 cm-1 that declares the presence of poly-acrylamide-...

Homogeneous photoinduced graft copolymerization of 4-vinyl pyridine (4-VP) onto ethyl cellulose (EC) in the presence of three photosensitizers such as 1-acetonaphthone (1-An), 2-acetonaph-thone (2-An), and biacetal (Bi) in benzene solution was extensively investigated. Ultraviolet (UV) irradiation in the range 310 to 460 nm was used. The U V spectra of the mentioned photosensitizers showed n-π∗ transitions. Grafting parameters such as grafting percentage (GP) and grafting efficiency (GE) were determined as functions of the irradiation time and the concentrations of monomer, substrate, and initiator. The IR spectrum of the EC-g-4-VP copolymer shows the appearance of new peaks between 1600 and 1690 cm-1 indicating the presence of poly-4-vinyl pyridine (p-4-VP) grafted chains. The rate of copolymerization of 4-VP onto EC in the presence of 1-An, 2-An, and Bi was determined as 0.98% min-1, 0.88% min-1 and 0.042% min-1, respectively. A good correlation was observed between the change in absorbance at ...

Some hydrogels of different chemical composition were synthesized using 2-hydroxyethyl methacrylate, methacrylic acid, acrylic acid, and acrylamide in different ratios and crosslinked by ethylene dimethacrylate. Effects of the copolymer composition as well as the type of monomers on some hydrogel characteristics were evaluated. Some characteristic properties, namely soluble fraction percentage, swelling degree, solution uptake, and salt uptake were found to be markedly affected by the hydrogel composition. Hydrogele verschiedener Zusammensetzung wurden aus Hydroxyethylmethacrylat, Methacrylsaaure, Acrylsaaure und Acrylsaaureamid und dem Vernetzer Ethylendimethacrylat in unterschiedlichen Molverhaaltnissen hergestellt. Der Einflus der Zusammensetzung der Copolymeren und die Struktur der Monomeren bestimmen die typischen Eigenschaften der einzelnen Hydro9gelproben. Es wurde gefunden, das besonders der laosliche Anteil, der Quellungsgrad und die Laosungs-und Salzaufnahme durch die Struktur der einzelnen Hydrogelproben bestimmt wird.

Graft copolymerization of chitosan with acrylonitrile (AN) was carried out by free radical polymerization using KMnO4 and oxalic acid as a combined redox initiator system. Graft copolymerization was confirmed by Fourier transform infrared spectra (FTIR), proton nuclear magnetic resonance spectra (1H-NMR), thermal gravimetric analysis (TGA) measurements, and wide angle X-ray diffraction (WAXD). In addition, further modification of the cyano groups of the grafted copolymers was performed by partial hydrolysis into carboxylic function groups with various extents. The extent of hydrolysis was monitored using FTIR spectroscopy. The potential of the hydrolyzed and unhydrolyzed grafted copolymers as polymeric carriers for drug delivery systems was extensively studied by preparation of tablets incorporated with methyl orange (MO) as a drug model. In vitro drug release was carried out in simulated gastric and intestinal conditions. The effects of grafting percentage (GP) and the extent of hydrolysis on the release kinetics were evaluated. Release continued up to 24 h for both hydrolyzed and unhydrolysed chitosan-g-PAN copolymers. The nature of drug transport through the polymer matrices was studied by comparing with power law or Kormeyer-Peppas equation. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Cross-linked magnetic chitosan-isatin Schiff's base resin (CSIS) was prepared for adsorption of metal ions. CSIS obtained was investigated by means of FTIR, 1 H NMR, wide-angle X-ray diffraction (WAXRD), magnetic properties and thermogravimetric analysis (TGA). The adsorption properties of cross-linked magnetic CSIS resin toward Cu 2+ , Co 2+ and Ni 2+ ions were evaluated. Various factors affecting the uptake behavior such as contact time, temperature, pH and initial concentration of the metal ions were investigated. The kinetic parameters were evaluated utilizing the pseudo-first-order and pseudo-second-order. The equilibrium data were analyzed using the Langmuir, Freundlich, and Tempkin isotherm models. The adsorption kinetics followed the mechanism of the pseudo-second-order equation for all systems studied, evidencing chemical sorption as the rate-limiting step of adsorption mechanism and not involving a mass transfer in solution. The best interpretation for the equilibrium data was given by Langmuir isotherm, and the maximum adsorption capacities were 103.16, 53.51, and 40.15 mg/g for Cu 2+ , Co 2+ and Ni 2+ ions, respectively. Cross-linked magnetic CSIS displayed higher adsorption capacity for Cu 2+ in all pH ranges studied. The adsorption capacity of the metal ions decreased with increasing temperature. The metal ion-loaded cross-linked magnetic CSIS were regenerated with an efficiency of greater than 88% using 0.01–0.1 M ethylendiamine tetraacetic acid (EDTA).

Polymere prepare a partir de l'acide 1,2-O(vinyl-4 phenyl) boronate L-mandelique en presence d'une base polymerisable telle que la vinyl-2(4) pyridine

L-Mandelic acid-1,2-O-(4-vinylphenyl)boronate (2) was copolymerized with divinylbenzene to yield a highly crosslinked macroporous polymer. 59% of incorporated L-mandelic acid (used as template) could be split-off on hydrolysis. The resulting polymer, with phenylboronic acid groups in the chiral cavities of type P1, was equilibrated in a batch process with D,L-mandelic acid in acetonitrile. The change of covering percentage, and that of the efficiency for racemic resolution, with time were followed by acidimetric titration and measurement of the optical rotation. A reasonable mechanism for the polymer-substrate interaction could de deduced. The selectivity terms for each of the forward and reverse reaction could be separately evaluated. Diffusional limitations significantly affect the observed efficiency of racemic resolution. Thermodynamically controlled separation, attainable by a suggested exchange reaction, required much more time than the considerably less effective kinetically controlled separation.

Als Ausgangssubstanzen zur Einfuhrung von funktionellen Gruppen in Polymere in vorgegebener Nachbarschaftsbeziehung wurden eine Reihe von polymerisierbaren D-Glycerinsaurederivaten synthetisiert, u. a. D-Glycerinsaure-(p-vinylanilid)-2,3-O-(p-vinylphenylboronat) (1a) sowie von 1a abgeleitete Homologe mit einer Athylengruppe zwischen der Amido- bzw. der Boronatgruppe und dem Benzolring (6, 7 und 8). Auserdem wurden die p-Vinyl-phenylboronate der D-Glycerinsaureester des Methanols (11a), des n-Octanols (11b), des Benzylalkohols (11c) und des p-Nitrobenzylalkohols (11d) dargestellt. Polymers of Enzyme-Analogous Structure, III On the Synthesis of Polymerizable Derivatives of D-Glyceric Acid As starting materials for the introduction of functional groups into polymers in a given spatial relationship a number of polymerizable derivatives of D-glyceric acid were prepared, including D-glyceric (p-vinylanilide) 2,3-O-(p—vinylphenylboronate) (1a). In addition compounds derived from 1a have been prepared in which the amido and the boronate groups are separated from the benzene ring by a spacer of a ethylene group (6,7, and 8). Furthermore the p-vinylphenylboronates of D-glyceric acid esters of methanol (11a), n-octanol (11b), benzyl alcohol (11c), and p-nitrobenzyl alcohol (11d) have been prepared.

By copolymerization of 4-nitrophenyl α-D-mannopyranoside-2,3;4,6-di-O-(4-vinylphenylboronate) (1) with ethylene dimethacrylate and methyl methacrylate macroporous polymers were obtained, in which after cleavage of the template, 4-nitrophenyl α-D-mannopyranoside (2), chiral cavities with two boronic acid groups are present. From the dependence of the specificity for the resolution of racemates on the covering percentage of the cavities the frequency distribution of the specificity of the cavities could be deduced. With the distribution curve at hand the factors are discussed, which govern the conservation and the loss of specificity.

The photodegradation of the synthetic rubbers cis -1,4-polybutadiene, polystyrenebutadiene and polyisoprene was studied. The chemical structure of the polymers as well as the effect of changing the solvent and the additive were particularly taken into consideration. The polychloroprene rubber in this study was irradiated either as a film or in solution. The presence of methylene blue affects the endothermic peaks observed in its differential scanning calorimetry diagrams. Methylene blue acts as a photostabilizer dye in solutions and films of polychloroprene. Mixtures of methylene blue, β-carotene as a singlet oxygen quencher and Fmbanox as a known anti-oxidant showed synergystic behaviour.

D-N-(4-vinylphenyl)carbamoylethylenedioxy(4-vinylphenyl)borane (1) with D-glyceric acid as template was copolymerized with technical divinylbenzene by a radical mechanism in the presence of various amounts of acetonitrile as an inert solvent. The resulting differences in the structure and swellability of the polymers are discussed in relation to the specificity of the polymers for the racemic resolution of D,L-glyceric acid. Some of these polymers were found to be able to bind glyceric acid with high optical enrichment by a covalent amide bond. To prevent the formation of the covalent amide bond during the intake reaction, the amide bond in the monomer is replaced by an ion pair relation. For this intention, the synthesis of an appropriate monomer 4-vinyltrimethylanilinium 2-(4-vinylphenyl)-1,3,2-dioxaborolan-4-carboxylate (2) and the investigation of the resulting polymers are described.

The binding ability of a macroporous polymer-supported phenylboronic acid for mandelic acid increases markedly in the presence of various N -bases. Based on a correlation between the relative increase of binding ability and the base strength, the existence of co-operative binding of the types P7 and P9 , through polymer-bound phenylboronic acid groups and freely interacting N -bases, could be deduced. A remarkable improvement of the efficiency for racemic resolution of d,l -mandelic acid on such polymers was achieved if both of the co-operating functionalities were introduced in a fixed stereochemical arrangement within the chiral polymeric cavities with a specific shape corresponding to the chemical structure of a template molecule, i.e. l -mandelic acid. Thus l -mandelic acid-1,2- O -(4-vinylphenyl)boronate ( 2 ) was copolymerized with a molar quantity of 4-vinylpyridine to highly crosslinked macroporous polymers ( P10 ). The resulting polymers, after removal of the template, exhibit separation factors of up to 1.29. The reason for specific binding is discussed and compared with that of polymers with chiral cavities of the type P1 , prepared from 2 according to Scheme 1.

With the aid of a chiral template molecule functional groups could be placed in a highly crosslinked polymer in such a way that they are present in a chiral cavity in a given stereochemistry. By this method methyl, resp. 4-nitrophenyl α-D-mannopyranoside-2,3; 4,6-di-O-(4-vinylphenylboronate) (1a, resp. 1b) were copolymerized to macroporous polymers from which the templates methyl, resp. 4-nitrophenyl α-D-mannopyranoside (2a, resp. 2b) could be split off in return. It could be shown that such polymers with two boronic acid groupings within the chiral cavity possess a good ability for the resolution of racemates of the template used. In the case of the separation of the enantiomers of 2b separation factors up to 2,27 could be obtained. The overall optical enrichment in a chromatographic separation amounted to 87%.

With the aid of D-glyceric acid as a template, an amino- and a boronic acid group, respectively, were introduced in a defined steric arrangement into polymers. For this, the monomer D-N-(4-vinylphenyl)carbamoylethylenedioxy(4-vinylphenyl)borane (1) was copolymerized into macroporous polymers under various conditions. The template D-glyceric acid was split off from the polymer with 20% HCl in methanol. The specificity of the polymers obtained with one amino- and one boronic acid group, respectively, per cavity was derived from their ability to resolve racemic glyceric acid. Racemic resolution was also observed on equilibration of the polymers with D,L-methyl glycerate and D,L-glyceraldehyde.

Three derivatives of diamagnetic diacetyl-monooxime benzoylhydrazone nickel(II) chelates were evaluated as uv stabilisers for cis -1,4-polybutadiene (BR) in solution and in films. In the presence of methylene blue (MB) as singlet oxygen sensitiser, such chelates inhibit the effect of singlet oxygen formed during irradiation by visible light. The photo-stabilising mechanism of the chelates is discussed in terms of their action as singlet oxygen quencher as well as their action as uv absorbers. Further, a stabilising mechanism which involves the trapping of alkyloxy and/or alkylperoxy radicals has also been suggested for two of the chelates. Combination of the most effective chelate and β-carotene as singlet oxygen quencher exhibits synergistic behaviour. The polymer samples which were irradiated in its presence were examined using the Differential Scanning Calorimeter (DSC) technique. The results obtained also demonstrate the photo-stabilising effect of the chelate.

Two different types of network were synthesized. Semi-IPN macrogel type PVA@P(AMPS- co -AAc) (SIMT) and PVA- EPC@P(AMPS- co -AAc) (100 nm) nanogel (CCPNT). Poly (vinyl alcohol) (PVA) was used as matrix and copolymerized 2-acrylamido-2-methyl-1-propane- sulfonic acid (AMPS), Acrylic acid (AAc) based materials were used in the removal of methylene blue (MB). Epichlororhydrine (EPC) was used as crosslinker to link the CCPNT. The maximum removal for MB was observed at (10AAc- co -90AMPS) (wt.:wt. %) monomer ratio for both networks. The prepared macro and nanogel materials were characterized by SEM, BET, TEM and DLS. The adsorption followed pseudo-second-order kinetics and fit Langmuir-type isotherm. The adsorption capacity was found to be equal to 416.6 mg/g, 181.8 mg/g for CCPNT and SIMT, respectively.

Glutathione S-transferases have been purified (18-fold) in 65-70% yield from the liver of one humped camel using affinity chromatography on glutathione-linked agarose. Chromatofocusing technique resolves the glutathione S-transferases into seven distinct isoenzymes with apparent pI of 8.7, 8.4, 8.0, 7.8, 7.3 and 6.5. The major isoenzyme (pI 8.7) which accounted for over 95% of the total activity was composed of two identical subunits of molecular mass 24,000 and was immunologically similar to the other six isoenzymes. The substrate specificities and the effect of various inhibitors on the activity of the abundant camel liver isoenzyme were also examined.

Enantioselective synthesis of homoallylic alcohols by nucleophilic addition of chirally modified allylboron reagents to aldehydes was investigated. Reaction of enantiopure N -sulfonylamino alcohols ( 1a, 1b, 3a, 4a ) with triallylborane gave the chiral allylboration reagents. Aldehydes were converted to enantioenriched homoallylic alcohols with the reagents. Polymer-supported chiral allylboron reagents were also prepared from triallylborane and crosslinked polymers having chiral N -sulfonylamino alcohol moieties ( 5–8 ). These polymeric reagents reacted with aldehydes to give optically active homoallylic alcohols in high chemical yield with high enantioselectivities. Optical yield up to 92% ee was obtained by the use of polymeric chiral ligand 7 derived from d -camphor. The potential of this type of approach in asymmetric synthesis is discussed.