Dye‐ligand column chromatography: Albumin adsorption from aqueous media and human plasma with dye‐affinity microbeads

Cibacron Blue F3GA was covalently coupled with poly(ethylene glycol‐dimethacrylate‐2‐hydroxyethylmethacrylate) [poly(EGDMA‐HEMA)] microbeads via the nucleophilic substitution reaction between the chloride of its triazine ring and the hydroxyl groups of the HEMA molecules under alkaline conditions. The affinity sorbent carrying 16.5 μmol Cibacron Blue F3GA/g polymer was then used for bovine serum albumin (BSA) adsorption from aqueous protein solutions and from human plasma in a packed‐bed column. The BSA adsorption capacity of the microbeads decreased with an increase in the recirculation rate. High adsorption rates were observed at the beginning, then equilibrium was gradually achieved in about 60 min. The BSA concentration in the mobile phase was also effective on adsorption. BSA adsorption was first increased with BSA concentration, then reached a plateau that was about 57.3 mg BSA/g. Higher BSA adsorption was observed at lower ionic strength. The maximum adsorption was observed at pH 5.0, which is the isoelectric pH of BSA. Higher human serum albumin adsorption was achieved from human plasma (109.6 mg HSA/g). High desorption ratios (over 94% of the adsorbed albumin) were achieved by using 1.0M NaSCN (pH 8.0) in 30 min. It was observed that albumin could be repeatedly adsorbed and desorbed without a significant loss in adsorption capacity. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 2803–2810, 1999     

Porous dye affinity beads for albumin separation from human plasma

Porous polymeric beads were obtained by the suspension polymerization of 2‐hydroxyethyl methacrylate (HEMA) and ethylene glycol dimethacrylate (EGDMA). Poly(HEMA–EGDMA) beads were characterized by surfacearea measurements, swelling studies, FTIR, scanning electron microscopy (SEM), and elemental analysis. Poly (HEMA–EGDMA) beads had a specific surface area of 56 m²/g. SEM observations showed that the poly(HEMA–EGDMA) beads abounded macropores. Poly(HEMA–EGDMA) beads with a swelling ratio of 55%, and containing different amounts of Reactive Red 120 (9.2–39.8 μmol/g) were used in the adsorption/desorption of human serum albumin (HSA) from aqueous solutions and human plasma. The nonspecific adsorption of HSA was very low (0.2 mg/g). The maximum HSA adsorption amount from aqueous solution in phosphate buffer was 60.1 mg/g at pH 5.0. Higher HSA adsorption value was obtained from human plasma (up to 95.7 mg/g) with a purity of 88%. The equilibrium monolayer adsorption amount, Q_max was determined as 172.4 mg/g. The dimensionless separation factor (R_L) value shows that the adsorption behavior of HSA onto the Reactive Red 120 attached poly(HEMA–EGDMA) beads was favorable (0 < R_L < 1). Desorption of HSA from Reactive Red 120 attached poly (HEMA–EGDMA) beads was performed using 0.1M Tris/HCl buffer containing 0.5M NaCl. It was observed that HSA could be repeatedly adsorbed and desorbed with Reactive Red 120‐attached poly(HEMA–EGDMA) beads without significant loss in the adsorption amount. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Metal chelating properties of Cibacron Blue F3GA‐derived poly(EGDMA‐HEMA) microbeads

Metal chelating properties of Cibacron Blue F3GA‐derived poly(EGDMA‐HEMA) microbeads have been studied. Poly(EGDMA‐HEMA) microbeads were prepared by suspension copolymerization of ethylene glycol dimethacrylate (EGDMA) and hydroxy‐ethyl methacrylate (HEMA) by using poly(vinyl alcohol), benzoyl peroxide, and toluene as the stabilizer, the initiator, and the pore‐former, respectively. Cibacron Blue F3GA was covalently attached to the microbeads via the nucleophilic substitution reaction between the chloride of its triazine ring and the hydroxyl groups of the HEMA, under alkaline conditions. Microbeads (150–200 μm in diameter) with a swelling ratio of 55%, and carrying 16.5 μmol Cibacron Blue F3GA/g polymer were used in the adsorption/desorption studies. Adsorption capacity of the microbeads for the selected metal ions, i.e., Cu(II), Zn(II), Cd(II), Fe(III), and Pb(II) were investigated in aqueous media containing different amounts of these ions (5–200 ppm) and at different pH values (2.0–7.0). The maximum adsorptions of metal ions onto the Cibacron Blue F3GA‐derived microbeads were 0.19 mmol/g for Cu(II), 0.34 mmol/g for Zn(II), 0.40 mmol/g for Cd(II), 0.91 mmol/g for Fe(III), and 1.05 mmol/g for Pb(II). Desorption of metal ions were studied by using 0.1 M HNO₃. High desorption ratios (up to 97%) were observed in all cases. Repeated adsorption/desorption operations showed the feasibility of repeated use of this novel sorbent system. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1397–1403, 1999     

Comparison of metal chelate affinity sorption of BSA onto Dye/Zn (II)-derived poly(ethylene glycol dimethacrylate-hydroxyethyl methacrylate) microbeads

Poly(ethylene glycol dimethacrylate-hydroxyethyl methacrylate) [poly-(EGDMA-HEMA)]microbeads in the size range of 150–200 μm were produced by a modified suspension copolymerization of EGDMA and HEMA. The dyes (Congo red, Cibacron blue F3GA, and alkali blue 6B) were covalently immobilized; then, Zn(II) ions were incorporated within the microbeads by chelation with the dye molecules. The maximum amounts of dye loadings were 14.5 μmol/g, 16.5 μmol/g, and 23.7 μmol/g for Congo red, Cibacron blue F3GA, and alkali blue 6B, respectively. Different amounts of Zn(II) ions(2.9–53.8 mg/g polymer) were incorporated on the microbeads by changing the initial concentration of Zn(II) ions and the pH of the medium. Bovine serum albumin (BSA) adsorption onto dye/Zn(II)-derived microbeads containing Congo red, Cibacron blue F3GA, and alkali blue 6B was investigated. The maximum BSA adsorptions onto the dye/Zn(II)-derived microbeads from aqueous solutions containing different amounts of BSA were 159 mg/g, 122 mg/g, and 93 mg/g for the Congo red, Cibacron blue F3GA, and alkali blue 6B dyes, respectively. The maximum BSA adsorptions were observed at pH 6.0 in all cases. Desorption of BSA molecules was achieved by using 0.025M EDTA (pH 4.9). High desorption ratios (more than 93% of the adsorbed BSA) were observed in all cases. It was possible to reuse these novel metal chelate sorbents without significant losses in their adsorption capacities. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 2085–2093, 1997     

Albumin adsorption from aqueous solutions and human plasma in a packed-bed column with Cibacron Blue F3GA-Zn(II) attached poly(EGDMA-HEMA) microbeads

Affinity dye-ligand Cibacron Blue F3GA, was covalently coupled with poly(EGDMA-HEMA) microbeads via nucleophilic reaction between the chloride of its triazine ring and the hydroxyl groups of the HEMA under alkaline conditions. The microbeads carrying 16.5 μmol Cibacron Blue F3GA per gram polymer was incorporated with Zn(II) ions. Zn(II) loading was 189.6 μmol/g. Cibacron Blue F3GA-Zn(II) attached affinity sorbent was used for albumin adsorption from aqueous solutions and human plasma in a packed-bed column. BSA adsorption capacity of the microbeads decreased with an increase in the recirculation rate. High adsorption rates were observed at the beginning, then equilibrium was gradually achieved in about 60 min. The BSA concentration in the mobile phase also effected adsorption. BSA adsorption was first increased with BSA concentration, then reached a plateau which was about 128 mg BSA/g. The maximum adsorption was observed at pH 5.0 which is the isoelectric pH of BSA. Higher human serum albumin adsorption was observed from human plasma (215 mg HSA/g). High desorption ratios (over 90% of the adsorbed albumin) were achieved by using 1.0 M NaSCN (pH 8.0) in 30 min.     

Preparation and characterization of comb type polymer coated poly(HEMA/EGDMA) microspheres containing surface-anchored sulfonic acid: Application in γ-globulin separation

Poly(2-hydroxyethyl methacrylate/ethylenglycol dimethacrylate), poly(HEMA/EGDMA) microspheres was prepared via suspension polymerization. After activation of the hydroxyl groups of poly(HEMA/EGDMA) by bromination, surface-initiated atom transfer radical polymerization (ATRP) of glycidylmethacrylate was conducted in dioxane/bipyridine mixture with CuBr as catalyst at 65 °C. The epoxy groups of the poly(glycidylmethacrylate) comb polymer were converted into sulfonic acid groups (as proton-exchange groups) with reaction of sodium sulfite. Synthesized microspheres were characterized by swelling studies, FT-IR spectroscopy, scanning electron microscopy (SEM) and elemental analysis. The microspheres were used as ion-exchange support for adsorption and purification of human γ-globulin (IgG). The maximum γ-globulin adsorption on the ion-exchange adsorbents was observed at between pH 5.0 and 6.0. The IgG adsorption onto the poly(HEMA/EGDMA) microspheres was negligible. The maximum amount of adsorbed γ-globulin was found to be 230.1 mg/g microspheres. The ion-exchange adsorbents allowed one-step separation of IgG from human plasma. The γ-globulin molecules could be repeatedly adsorbed and desorbed with this ion-exchange support without noticeable loss in their IgG adsorption capacity.     

Congo red- and Zn(II)-derivatized monosize poly(MMA-HEMA) microspheres as specific sorbent in metal chelate affinity of albumin

Monosize poly(methylmethacrylate-hydroxyethylmethacrylate) [poly(MMA-HEMA)] microspheres (4 μm in diameter) were produced by dispersion copolymerization of MMA and HEMA in an ethanol-water medium. Congo Red was attached to the poly(MMA-HEMA) microspheres, covalently. These Congo Red-derivatized microspheres were characterized by optical microscopy, Fourier transform infrared spectroscopy, and elemental analysis. Then, Zn(II) ions were incorporated by chelating with the immobilized Congo Red molecules. Different amounts of Zn(II) ions [1.2–17.6 mg of Zn(II)/g of polymer] were conjugated on the microspheres by changing the initial concentration of Zn(II) ions and pH. Bovine serum albumin (BSA) adsorption on these microspheres from aqueous solutions containing different amounts of BSA at different pH and ionic strengths was investigated in batch reactors. The nonspecific BSA adsorption on the plain poly(MMA-HEMA) microspheres was very low (0.7 mg of BSA/g of polymer). Congo Red derivatization significantly increased the BSA adsorption (up to 35.8 mg of BSA/g of polymer). A further increase in the adsorption capacity (up to 61.0 mg of BSA/g of polymer) was observed when Zn(II) ions were incorporated. More than 90% of the adsorbed BSA was desorbed in 1 h in the desorption medium containing 1.0M NaSCN at pH 8.0. © 1997 John Wiley & Sons, Inc.     

Congo red attached poly(EGDMA–HEMA) microspheres as specific sorbents for removal of cadmium ions

Poly[ethyleneglycoldimethacrylate (EGDMA)–hydroxyethylmethacrylate (HEMA)] microspheres (150–200 μm in diameter) were produced by suspension copolymerization of EGDMA and HEMA in an aqueous medium. Toluene was included in the formulations in order to produce water-swellable microspheres. Poly(vinyl alcohol) and benzoyl peroxide were used as stabilizer and initiator, respectively. Congo red was chemically attached to the microspheres as a metal chelating ligand for specific adsorption of heavy metal ions. These sorbents were characterized by an optical microscopy and a FTIR. Adsorption/desorption of cadmium (Cd²⁺) ions from aqueous solutions on these sorbents were investigated in batch equilibrium experiments by using an atomic absorption spectroscopy with a graphite furnace atomizer. The maximum cadmium adsorption on to the dye-attached microspheres (i.e., by complex formation) was about 18.3 mg Cd²⁺ ions/g polymer, which was observed at pH 6.8. While adsorption onto the plain poly(EGDMA–HEMA) microspheres (i.e., nonspecific adsorption) was about 0.93 mg Cd²⁺ ions/g polymer at the same conditions. More than 90% of the adsorbed cadmium was desorbed in 1 h by using 2M NaCl as an eluant. The resorption capacity of the sorbent did not significantly decrease during repeated sorption–desorption cycling. © 1996 John Wiley & Sons, Inc.     

Preparation of a novel metal‐chelate affinity beads for albumin isolation from human plasma

In this study, we developed a novel approach to obtain a high protein‐adsorption capacity utilizing 2‐methacryloylamidohistidine (MAH) as a biollgand. MAH was synthesized by reacting methacryloyl chloride and histidine. Spherical beads, with an average size of 150–200 μm, were obtained by the radical suspension polymerization of MAH, ethyleneglycol dimethacrylate (EGDMA), and 2‐hydroxyethyl methacrylate (HEMA) conducted in an aqueous dispersion medium. p(EGDMA–HEMA–MAH) beads had a specific surface area of 17.6 m²/g. The synthesized MAH monomer was characterized by NMR. p(EGDMA–HEMA–MAH) beads were characterized by a swelling test, FTIR, and elemental analysis. Then, Cu(II) ions were incorporated into the beads and Cu(II) loading was found to be 0.96 mmol/g. These beads, with a swelling ratio of 65% and containing 1.6 mmol MAH/g, were used in the adsorption/desorption of human serum albumin (HSA) from both aqueous solutions and human serum. The adsorption of HSA onto p(EGDMA–HEMA–MAH) was low (8.8 mg/g). Cu(II) chelation onto the beads significantly increased the HSA adsorption (56.3 mg/g). The maximum HSA adsorption was observed at pH 8.0 Higher HSA adsorption was observed from human serum (94.6 mg HSA/g). Adsorptions of other serum proteins were obtained as 3.7 mg/g for fibrinogen and 8.5 mg/g for γ‐globulin. The total protein adsorption was determined as 107.1 mg/g. Desorption of HSA was obtained using a 0.1M Tris/HCI buffer containing 0.5M NaSCN. High desorption ratios (to 98% of the adsorbed HSA) were observed. It was possible to reuse Cu(II)‐chelated p(EGDMA–HEMA–MAH) beads without significant decreases in the adsorption capacities. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2840–2847, 2003     

Cu(II)‐incorporated,histidine‐containing,magnetic‐metal‐complexing beads as specific sorbents for the metal chelate affinity of albumin

N‐Methacryloyl‐(L )‐histidine methyl ester (MAH) was synthesized from metharyloyl chloride and histidine. Spherical beads with an average size of 150–250 μm were obtained by the suspension polymerization of ethylene glycol dimethacrylate and MAH in an aqueous dispersion medium. Magnetic poly(ethylene glycol dimethacrylate‐co‐N‐Methacryloyl‐(L )‐histidine methyl ester) [m‐p(EGDMA‐co‐MAH)] microbeads were characterized with swelling tests, electron spin resonance, elemental analysis, and scanning electron microscopy. The specific surface area of the beads was 80.1 m²/g. m‐p(EGDMA‐co‐MAH) microbeads with a swelling ratio of 40.2% and 43.9 μmol of MAH/g were used for the adsorption of bovine serum albumin (BSA) in a batch system. The Cu(II) concentration was 4.1 μmol/g. The adsorption capacity of BSA on the Cu(II)‐incorporated beads was 19.2 mg of BSA/g. The BSA adsorption first increased with the BSA concentration and then reached a plateau, which was about 19.2 mg of BSA/g. The maximum adsorption was observed at pH 5.0, which was the isoelectric point of BSA. The BSA adsorption increased with decreasing temperature, and the maximum adsorption was achieved at 4°C. High desorption ratios (>90% of the adsorbed BSA) were achieved with 1.0M NaSCN (pH 8.0) in 30 min. The nonspecific adsorption of BSA onto the m‐p(EGDMA‐co‐MAH) beads was negligible. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2669–2677, 2004     

Porous dye affinity beads for nickel adsorption from aqueous solutions: A kinetic study

We investigated a new adsorbent system, Reactive Red 120 attached poly(2‐hydroxyethyl methacrylate ethylene dimethacrylate) [poly(HEMA–EDMA)] beads, for the removal of Ni²⁺ ions from aqueous solutions. Poly(HEMA–EDMA) beads were prepared by the modified suspension copolymerization of 2‐hydroxyethyl methacrylate and ethylene dimethacrylate. Reactive Red 120 molecules were covalently attached to the beads. The beads (150–250 μm), having a swelling ratio of 55% and carrying 25.5 μmol of Reactive Red 120/g of polymer, were used in the removal of Ni²⁺ ions. The adsorption rate and capacity of the Reactive Red 120 attached poly(HEMA–EDMA) beads for Ni²⁺ ions was investigated in aqueous media containing different amounts of Ni²⁺ ions (5–35 mg/L) and having different pH values (2.0–7.0). Very high adsorption rates were observed at the beginning, and adsorption equilibria were then gradually achieved in about 60 min. The maximum adsorption of Ni²⁺ ions onto the Reactive Red 120 attached poly(HEMA–EDMA) beads was 2.83 mg/g at pH 6.0. The nonspecific adsorption of Ni²⁺ ions onto poly(HEMA–EDMA) beads was negligible (0.1 mg/g). The desorption of Ni²⁺ ions was studied with 0.1M HNO₃. High desorption ratios (>90%) were achieved. The intraparticle diffusion rate constants at various temperatures were calculated as k_20°C = 0.565 mg/g min^0.5, k_30°C = 0.560 mg/g min^0.5, and k_40°C = 0.385 mg/g min^0.5. Adsorption–desorption cycles showed the feasibility of repeated use of this novel adsorbent system. The equilibrium data fitted very well both Langmuir and Freundlich adsorption models. The pseudo‐first‐order kinetic model was used to describe the kinetic data. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100:5056–5065, 2006     

A poly(2-hydroxyethyl methacrylate)-based immobilized metal affinity chromatography adsorbent for protein purification

Poly(HEMA) microbeads were prepared by suspension polymerization of 2-hydorxyethylmethacrylate and ethyleneglycoldimethacrylate (EGDMA). The water content, ligand density, and selectivity for poly(His)-tagged d-hydantoinase of the poly(HEMA)-based adsorbents were affected by the concentration of EDGMA used during polymerization. The Ni(II)-loaded poly(HEMA) adsorbent exhibited an adsorption capacity of 1.0 mg/g for poly(His)-tagged d-hydantoinase under optimal conditions with buffer containing 100-300 mM NaCl at pH 6.0. One-step purification protocol with the adsorbent gave a purity of at least 92%. The adsorption capacity of adsorbent declined by 54% after 7 cycles, due to the leaching of Ni(II) from the adsorbent. However, upon regeneration the adsorption capacity can be restored. Given the ease of preparation and the chemical and microbial resistance, the poly(HEMA)-based IMAC adsorbent could be a promising substitute for the polysaccharide-based IMAC adsorbents.     

Production and characterization of poly(ethylene glycol dimethacrylate-styrene-glycidyl methacrylate) microbeads

Nonswellable and swellable poly(ethyleneglycol dimethacrylate)-based microbeads that could react directly with the biological molecules were produced by a suspension polymerization procedure. For this purpose, ethyleneglycol dimethacrylate (EGDMA) was copolymerized with glycidyl methacrylate (GMA) in an aqueous suspension medium. Benzoyl peroxide and poly(vinyl alcohol) were used as the initiator and the stabilizer, respectively. The copolymerization provided nonswellable, tranparent, and spherical copolymer microbeads in the size range of 100–300 μm. On the other hand, swellable copolymer microbeads in the aqueous medium were obtained by using toluene as a diluent in the same copolymerization recipe. In a separate group of polymerizations, styrene (St) monomer was also included within the monomer phase to regulate the hydrophobicity of resulting microbeads. Nonswellable and swellable poly-(EGDMA-St-GMA) microbeads were obtained by changing the type and concentration of the ingredients within the monomer phase. The effects of glycidyl methacrylate, styrene, and toluene concentrations on the microbead yield, the average size, and the swellability of microbeads were investigated. In the second part of the study, the interaction of produced microbeads with a selected enzyme (i.e., chymotrypsin) was investigated. The most stable chymotrypsin immobilization was achieved with the swellable poly(EGDMA)-based microbeads including styrene. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:1319–1334, 1998     

Antibody purification using porous metal–chelated monolithic columns

A novel monolithic material was developed to obtain efficient and cost‐effective purification of IgG from human plasma. The porous monolith was obtained by bulk polymerization in a glass tube of 2‐hydroxyethyl methacrylate (HEMA) and N‐methacryloyl‐(L )‐histidine methyl ester (MAH). The poly(HEMA‐MAH) monolith had a specific surface area of 214.6 m²/g and was characterized by swelling studies, porosity measurement, FTIR, scanning electron microscopy, and elemental analysis. Then the monolith was loaded with Cu²⁺ ions to form the metal chelate. Poly(HEMA‐MAH) monolith with a swelling ratio of 74% and containing 20.9 μmol MAH/g was used in the adsorption/desorption of IgG from aqueous solutions and human plasma. The maximum adsorption of IgG from an aqueous solution in phosphate buffer was 10.8 mg/g at pH 7.0. Higher adsorption was obtained from human plasma (up to 104.2 mg/g), with a purity of 94.1%. It was observed that IgG could be repeatedly adsorbed and desorbed with the poly(HEMA‐MAH) monolith without significant loss of adsorption capacity. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 395–404, 2006     

Preparation of Zn2+‐chelated poly(HEMA‐MAH) cryogel for affinity purification of chicken egg lysozyme

Supermacroporous poly(2‐hydroxyethyl methacrylate) [poly(HEMA)]‐based monolithic cryogel column was prepared by radical cryocopolymerization of HEMA with N‐methacryloyl‐L ‐histidine methyl ester (MAH) as functional comonomer and N,N′‐methylene‐bisacrylamide (MBAAm) as crosslinker directly in a plastic syringe for affinity purification of lysozyme from chicken egg white. The monolithic cryogel containing a continuous polymeric matrix having interconnected pores of 10–50 μm size was loaded with Zn²⁺ ions to form the metal chelate with poly(HEMA‐MAH) cryogel. Poly(HEMA‐MAH) cryogel was characterized by swelling studies, FTIR, scanning electron microscopy, and elemental analysis. The equilibrium swelling degree of the poly(HEMA‐MAH) monolithic cryogel was 5.62 g H₂O/g cryogel. Poly(HEMA‐MAH) cryogel containing 45.8 μmol MAH/g was used in the adsorption/desorption of lysozyme from aqueous solutions. The nonspecific adsorption of lysozyme was very low (7.5 mg/g). The maximum amount of lysozyme adsorption from aqueous solution in phosphate buffer was 209 mg/g at pH 7.0. It was observed that lysozyme could be repeatedly adsorbed and desorbed with the poly(HEMA‐MAH) cyogel without significant loss of adsorption capacity. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Pseudospecific magnetic affinity beads for immunoglobulin‐G depletion from human serum

Magnetic poly(ethylene glycol dimethacrylate‐N‐methacryloyl‐(L )‐histidine methyl ester) [m‐poly(EGDMA‐MAH)] beads were prepared by suspension polymerization for the affinity depletion of immunoglobulin‐G (IgG) from human serum in a batch system. Elemental analysis of the magnetic beads for nitrogen was estimated as 70 μmol MAH/g polymer. IgG adsorption onto the m‐poly(EGDMA) was negligible. Higher adsorption value (up to 46.8 mg/g) was obtained in which the m‐poly(EGDMA‐MAH) beads were used. IgG adsorption capacity of the magnetic beads increased with an increase in the concentration of IgG. The maximum IgG adsorption was observed at pH 6.5 for MOPS buffer. IgG molecules could be repeatedly adsorbed and eluted with these adsorbents, without noticeable loss in their IgG adsorption capacity. Adsorption capacity decreased for both increasing salt concentration and temperature. In this study, we show that m‐poly(EGDMA‐MAH) beads (wherein IgG molecules bind directly with the matrix) can be used directly for affinity depletion without further modification. Higher adsorption value was obtained from human serum (up to 85.7 mg/g). The elution results demonstrated that the adsorption of IgG to the adsorbent was reversible. The depletion efficiencies for IgG were above 85% for all studied concentrations. Eluted portion was analyzed for testing the IgG removal efficiency by two dimensional gel electrophoresis. Eluted proteins include mainly IgG, and a small number of nonalbumin proteins such as apolipoprotein A1, serotransferrin, haptoglobulin, and α1‐antitrypsin. IgA was not identified in eluted fraction. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

HSA immobilized novel polymeric matrix as an alternative sorbent in hemoperfusion columns for bilirubin removal

HSA immobilized poly(2-hydroxyethylmethacrylate), HSA-P[HEMA], cryogel monolith was examined as an alternative sorbent to be used in hemoperfusion columns for bilirubin removal from serum. The cryogel monolith synthesis was performed by free radical polymerization using MBAA as crosslinker, APS and TEMED as redox pair. Cyanogen bromide (CNBr) was used as a matrix-activating agent for the preparation of immobilized cryogels. Control cryogel monolith, P[HEMA], and HSA-P[HEMA] were characterized by swelling test, SEM images, porosity and surface area measurements, and blood compatibility tests. Activation and immobilization processes were optimized. The removal of bilirubin from plasma samples overloaded with bilirubin was performed using P[HEMA] cryogel monoliths containing different amounts of immobilized HSA in continuous mode. Several factors affecting adsorption capacity of the matrix such as incubation time, HSA concentration, bilirubin concentration in plasma and temperature were analysed. The maximum bilirubin removal from plasma was 25.4 mg/g at 37.5 °C. The desorption agent was 0.1 M NaOH and 1.0 M NaCl containing solution. The reusability was tested for 10 consecutive adsorption–desorption cycles. The adsorption isotherm models and kinetics of process were also studied.     

Dye‐affinity microbeads for removal of phenols and nitrophenols from aquatic systems

Alkali Blue 6B attached poly(2‐hydroxyethyl methacrylate) (PHEMA) microbeads were investigated as dye‐affinity adsorbents for the removal of phenol and nitrophenols (i.e., 2‐nitrophenol, 4‐nitrophenol, and 2,4‐dinitrophenol) from aqueous solutions. PHEMA microbeads were prepared by radical‐suspension polymerization of HEMA in the presence of azobisisobutyronitrile as the initiator. These microbeads with a swelling ratio of 55% and carrying 23.6 μmol Alkali Blue 6B/g polymer were then used in the removal of phenol and nitrophenols from aqueous media. The adsorption was fast in all cases (20‐min equilibrium time). The maximum adsorptions of phenols onto the microbeads carrying Alkali Blue 6B were 145.2 μmol/g for phenol, 87.8 μmol/g for 2,4‐dinitrophenol, 112.6 μmol/g for 4‐nitrophenol, and 104.3 μmol/g for 2‐nitrophenol. The affinity order was phenol > 4‐nitrophenol > 2‐nitrophenol > 2,4‐dinitrophenol. The adsorption of nitrophenols decreased with increasing pH. Desorption of nitrophenols was achieved using a 30% (v/v) methanol solution. The microbeads carrying Alkali Blue 6B are suitable for repeated use for more than five cycles without a noticeable loss of adsorption capacity. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2411–2418, 2002     

Vinyl triazole carrying metal‐chelated beads for the reversible immobilization of glucoamylase

Poly(ethylene glycol dimethacrylate–1‐vinyl‐1,2,4‐triazole) [poly(EGDMA–VTAZ)] beads with an average diameter of 100–200 μm were obtained by the copolymerization of ethylene glycol dimethacrylate (EGDMA) with 1‐vinyl‐1,2,4‐triazole (VTAZ). The copolymer hydrogel bead composition was determined by elemental analysis and was found to contain 5 EGDMA monomer units for each VTAZ monomer unit. The poly(EGDMA–VTAZ) beads were characterized by swelling studies and scanning electron microscopy (SEM). The specific surface area of the poly(EGDMA–VTAZ) beads was found 65.8 m²/g. Cu²⁺ ions were chelated on the poly(EGDMA–VTAZ) beads. The Cu²⁺ loading was 82.6 μmol/g of support. Cu²⁺‐chelated poly(EGDMA–VTAZ) beads with a swelling ratio of 84% were used in the immobilization of Aspergillus niger glucoamylase in a batch system. The maximum glucoamylase adsorption capacity of the poly(EGDMA–VTAZ)–Cu²⁺ beads was 104 mg/g at pH 6.5. The adsorption isotherm of the poly(EGDMA–VTAZ)–Cu²⁺ beads fitted well with the Langmuir model. Adsorption kinetics data were tested with pseudo‐first‐ and second‐order models. The kinetic studies showed that the adsorption followed a pseudo‐second‐order reaction model. The Michaelis constant value for the immobilized glucoamylase (1.15 mg/mL) was higher than that for free glucoamylase (1.00 mg/mL). The maximum initial rate of the reaction values were 42.9 U/mg for the free enzyme and 33.3 U/mg for the immobilized enzyme. The optimum temperature for the immobilized preparation of poly(EGDMA–VTAZ)–Cu²⁺–glucoamylase was 65°C; this was 5°C higher than that of the free enzyme at 60°C. The glucoamylase adsorption capacity and adsorbed enzyme activity slightly decreased after 10 batch successive reactions; this demonstrated the usefulness of the enzyme‐loaded beads in biocatalytic applications. The storage stability was found to increase with immobilization. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Preparation of poly(acrylamide) grafted onto crosslinked poly (HEMA-MMA-EGDMA) beads for the removal of phenol

ABSTRACT

Poly(acrylamide) (PAAM) was grafted onto crosslinked poly(hydroxy ethyl methacrylate) (HEMA)-based beads for the removal of phenol from aqueous solution. A beaded polymer with a PAAM surface shell was prepared in two steps: synthesis of crosslinked poly (HEMA (50% mol) - MMA (40% mol) - EGDMA (10% mol)) terpolymers spherical beads (200–420 µm) (resin 1) via the suspension polymerization method; and the grafting of PAAM was carried out by redox initiation from hydroxyl groups on resin1 by using cerium (IV) ammonium nitrate as the initiator.

The resulting polymeric sorbent (resin 2) with about 82 wt.% grafted PAAM has been demonstrated to be efficient to remove phenol from water. Moreover, phenol sorption capacities of resin 1 and resin 2 were compared and sorption experiments were performed depending on the initial phenol concentration and pH. Kinetic measurements and models were studied for resin 1 and resin 2.