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1.
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.  相似文献   

2.
Poly(2-hydroxyethyl methacrylate) [poly(HEMA)] membranes were prepared by UV-initiated photopolymerization of HEMA in the presence of an initiator (α-α′-azobis-isobutyronitrile, AIBN). The triazine dye Cibacron Blue F3GA was attached as an affinity ligand to poly(HEMA) membranes, covalently. These affinity membranes with a swelling ratio of 58% and containing 10.7 mmol Cibacron Blue F3GA/m2 were used in the albumin adsorption studies. After dye-attachment, Zn(II) ions were chelated within the membranes via attached-dye molecules. Different amounts of Zn(II) ions [650–1440 mg Zn(II)/m2] were loaded on the membranes by changing the initial concentration of Zn(II) ions and pH. Bovine serum albumin (BSA) adsorption on these membranes from aqueous solutions containing different amounts of BSA at different pH was investigated in batch reactors. The nonspecific adsorption of BSA on the poly(HEMA) membranes was negligible. Cibacron Blue F3GA attachment significantly increased the BSA adsorption up to 92.1 mg BSA/m2. Adsorption capacity was further increased when Zn(II) ions were attached (up to 144.8 mg BSA m2). More than 90% of the adsorbed BSA was desorbed in 1 h in the desorption medium containing 0.5M NaSCN at pH 8.0 and 0.025M EDTA at pH 4.9. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 657–664, 1998  相似文献   

3.
Lysozyme adsorption onto Cibacron Blue F3GA attached and Cu(II) incorporated poly(2-hydroxyethyl methacrylate–ethylene glycol dimethacrylate) [poly(HEMA-EGDMA)] microspheres was investigated. The microspheres were prepared by suspension polymerization. Various amounts of Cibacron Blue F3GA were attached covalently onto the microspheres by changing the initial concentration of dye in the reaction medium. The microspheres with a swelling ratio of 65%, and carrying different amounts of dye (between 1.4 and 22.5 µmol/g−1) were used in the lysozyme adsorption studies. Lysozyme adsorption on these microspheres from aqueous solutions containing different amounts of lysozyme at different pH values was investigated in batch reactors. The lysozyme adsorption capacity of the dye–metal chelated microspheres (238.2 mg g−1) was greater than that of the dye-attached microspheres (175.1 mg g−1). The maximum lyzozyme adsorption capacities (qm) and the dissociation constant (kd) values were found to be 204.9 mg g−1 and 0.0715 mg ml−1 with dye-attached and 270.7 mg g−1 and 0.0583 mg ml−1 with dye–metal chelated microspheres, respectively. More than 90% of the adsorbed lysozyme were desorbed in 60 min in the desorption medium containing 0.5 M KSCN at pH 8.0 or 25 mM EDTA at pH 4.9. © 1999 Society of Chemical Industry  相似文献   

4.
A series of monodisperse submicron polystyrene (PS) particles with different surface monomethoxy poly(ethylene glycol) (mPEG) densities were prepared and characterized. The effects of the chemically grafted mPEG chains (MW = 2,000) on the adsorption of bovine serum albumin (BSA) molecules onto these negatively charged particles at pHs 5 and 3 were investigated. The native particles at both pH values showed the largest values of q max (maximum amount of BSA adsorbed on the particle surface). The surface mPEG chains were very effective in retarding the BSA adsorption and q max decreased significantly with increasing surface mPEG density. The values of q max were greater for both the native and mPEG-modified particles at pH 5 compared to those counterparts at pH 3, due to the different adsorption mechanisms. Hydrophobic interaction predominated in the adsorption of BSA molecules on the particles at pH 5, whereas electrostatic interaction had a crucial influence on the BSA adsorption at pH 3. At pH 5, the adsorption behaviors were qualitatively explained by the calculated values of the free energy barrier against the BSA adsorption. A schematic model was also proposed to qualitatively describe the conformations of BSA molecules adsorbed on the particle surfaces.  相似文献   

5.
New hydrogel microspheres based on crosslinked dextran containing N,N′‐diethylaminoethyl (DEAE) groups with different chemical structures have been used in adsorption–desorption studies. Bovine serum albumin (BSA) is frequently used in biophysical and biochemical studies. BSA has a well‐known primary structure that has been associated with binding of many different categories of small molecules. Both adsorption kinetics and equilibrium isotherms for the adsorption of BSA on crosslinked DEAE dextran have been determined experimentally. These were only slightly dependent on the initial concentration of BSA but were considerably affected by the pH of the medium. The results fitted the Freundlich–Langmuir isotherm model for pH 6.9. The adsorption capacity factor and the adsorption equilibrium constant were obtained and mathematical modeling of adsorption, adsorption rate constants, and maximum adsorption were determined. Swelling kinetics of crosslinked DEAE dextran and optimum ionic strength, pH, and mass of hydrogel were also investigated. Desorption studies were finally determined under optimum medium conditions. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006  相似文献   

6.
《分离科学与技术》2012,47(17):2227-2244
Abstract

Equilibrium isotherms for adsorption of BSA on DEAE-dextran have been determined experimentally. They were little affected by the initial concentration of BSA but were considerably affected by pH. They were correlated by the Langmuir equation when pH ≥ 5.05 and by the Freundlich equation at pH 4.8 (≈ pI). The maximum amounts of inorganic anion exchanged for BSA were 1 and 0.4% of the exchange capacity of the ion exchanger at pH 6.9 and 4.8, respectively. When NaCl coexisted in the solution, the shape of the isotherm was similar to the Langmuir isotherm but was shifted to the right. When the concentration of NaCl was 200 mol/m3, BSA was not adsorbed on the resin. When BSA was dissolved in pure water, the saturation capacity of BSA on HPO4 2? -form resin was about 3.5 times larger than that with buffer (pH 6.9). The amount of BSA adsorbed on univalent-form resin decreased when the liquid-phase equilibrium concentration of BSA was increased.  相似文献   

7.
《分离科学与技术》2012,47(8):1270-1278
In this work, Reactive Blue 15 dye functionalized poly(HEMA) nanoparticles were synthesized for reversible adsorption of lysozyme from its aqueous solution. For this, nano-sized poly(HEMA) nanoparticles were synthesized by the surfactant free emulsion polymerization. Reactive Blue 15 dye then covalently attached to the polymeric structure. These novel dye attached poly(HEMA) nanoparticles were used for the adsorption of lysozyme. Characterization of dye attached nanoparticles was carried out by using FTIR, AFM, and elemental analysis. Incorporation of the dye onto the polymeric structure was demonstrated by FTIR and elemental analysis, while the size and the shape of the nanoparticles were shown by AFM. The incorporated amount of the dye was found to be 70.3 μmol/g nanoparticle with sulphur stoichiometry and it was found that the prepared nanoparticles were in a spherical form and were about 100 nm diameter. Lysozyme adsorption studies were carried out with different conditions (pH, lysozyme concentration, temperature, and ionic strength) and maximum lysozyme adsorption was found to be 630.7 mg/g nanoparticle at pH 7.0 in 25°C medium temperature. Adsorbed lysozyme was desorbed by 1.0 M of NaCl with 96% recovery and synthesized dye-attached nanoparticles were used 10 times without any decrease in their adsorption capacity.  相似文献   

8.
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  相似文献   

9.
Two poly(hydroxo aluminum) intercalated Wyoming bentonites were prepared starting from two different aluminum pillaring solutions. The sorption mechanism of Laurentian fulvic acid (FA) onto these poly(hydroxo aluminum) intercalated bentonites was investigated at different pH values and at different ionic strengths (NaCl or CaCl2). Three mechanisms contribute to the FA adsorption, depending on the pH and the nature (NaCl or CaCl2) and ionic strength of the background electrolyte. In the presence of NaCl the FA sorption onto poly(hydroxo aluminum) intercalated bentonites can be mainly ascribed to ligand exchange between the amphoteric poly(hydroxo aluminum) hydroxyl groups and the deprotonated carboxylic groups of the FA. The FA adsorption due to ligand exchange reactions decreases with increasing pH. In presence of Ca2+ ions the FA adsorption is enhanced, compared to the presence of Na+, due to Ca2+ bridging between negatively charged groups on the FA molecules and the poly(hydroxo aluminum) intercalated bentonite. The FA adsorption due to Ca2+ bridging increases with increasing pH. A third mechanism is enhanced FA adsorption ascribed to FA-Ca-FA bridging and was detected from the FA adsorption in presence of Ca2+ at the zero point of charge of the poly(hydroxo aluminum) bentonite (pH 5).  相似文献   

10.
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‐coN‐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  相似文献   

11.
Bovine serum albumin (BSA) adsorption onto novel and feasible magnetic polyvinylbutyral‐based microbeads was investigated. The microbeads were made of Mowital® B30HH, a commercial product, in the range 125–250 μm by a modified solvent evaporation technique. Magnetite particles were embedded in the polymer structure for favorable magnetic properties, 4.80 emu/g microbeads of saturation magnetization at 6000 Gauss magnetic field. Glutaraldehyde (GA) was used as a bonding agent to increase stability and as a ligand for protein adsorption. The amount of adsorbed BSA was optimized by changing the medium pH and the initial concentrations of GA and BSA. Dynamic adsorption data of batch runs fitted best to Langmiur kinetics. The parameters qmax, kf and kr of the model were estimated through nonlinear regression analysis as 138 mg BSA/g adsorbent, 0.058 ml/(mg BSA · min) and 0.002 min−1, respectively, for magnetic microbeads at pH 5.0 and 25°C. The adsorbed BSA was eluted successfully at pH 8.0 and 25°C. Possibly due to surface roughness and magnetic properties, qmax was found higher than the other adsorbents reported in the literature. The results denote that these microbeads can be an alternative protein adsorbent due to high adsorption capacity and rate, as well as remarkable separation characteristics. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 707–715, 2001  相似文献   

12.
BACKGROUND: Quantum dots (QDs) have attracted much attention in biological and medical applications. In particular, the interaction of QDs with bovine serum albumin (BSA) is crucial, and has been systematically investigated by various spectroscopic techniques under the physiological conditions. RESULTS: The effects of ionic strength and pH on the interaction of CdTe QDs with BSA were studied by changing NaCl concentration and pH in mixed solution and making fluorescence spectroscopic measurements. The Stern‐Volmer quenching constant (Ka) of different ionic strength and pH were calculated, and information on the structural features of BSA were discussed by means of circular dichroism (CD) spectrum. CONCLUSION: Both fluorescence (FL) and circular dichroism (CD) results indicated that hydrophobic and electrostatic interactions play a major role in the binding reaction, and the nature of quenching is static, resulting in forming QDs‐BSA complexes. Copyright © 2012 Society of Chemical Industry  相似文献   

13.
Magnetic nanoparticle composite with a cobalt ferrite (CoFe2O4, (CF)) core and an apatite (Ap) coating was synthesized using a biomineralization process in which a modified simulated body fluid (1.5SBF) solution is the source of the calcium phosphate for the apatite formation. The core–shell structure formed after the citric acid–stabilized cobalt ferrite (CFCA) particles were incubated in the 1.5 SBF solution for 1 week. The mean particle size of CFCA-Ap is about 750 nm. A saturation magnetization of 15.56 emug-1 and a coercivity of 1808.5 Oe were observed for the CFCA-Ap obtained. Bovine serum albumin (BSA) was used as the model protein to study the adsorption and release of the proteins by the CFCA-Ap particles. The protein adsorption by the CFCA-Ap particles followed a more typical Freundlich than Langmuir adsorption isotherm. The BSA release as a function of time became less rapid as the CFCA-Ap particles were immersed in higher pH solution, thus indicating that the BSA release is dependent on the local pH.  相似文献   

14.
An empirical model modified from the Langmuir isotherm model to account for the effects of ionic strength on the equilibrium characteristics of protein adsorption onto ion exchange/affinity adsorbents has been proposed and tested against experimental and literature data. The equilibrium isotherms for BSA adsorption onto a polystyrenic anion exchanger, Diaion HPA25, were established for five different NaCl concentrations at 25°C, pH 7.0. The apparent Langmuir parameters in the new model (qm′ and Kd′), which replace the Langmuir parameters (qm and Kd) in the original Langmuir model, were determined by non-linear curve fitting. The proposed model has been shown to be applicable to various protein/adsorbent systems.  相似文献   

15.
周笑鹏  白姝  孙彦 《化工学报》2005,56(1):130-134
采用孔扩散模型, 模拟不同盐浓度和不同蛋白质初始浓度条件下,吸附牛血清白蛋白(BSA)的动态吸附曲线并获得孔扩散系数;考察了离子强度和溶质浓度对蛋白质在阴离子交换剂Q Sepharose FF中吸附动力学的影响.结果表明,蛋白质的孔扩散系数随初始浓度的增大而下降;在氯化钠浓度小于0.10 mol•L-1的范围内,蛋白质的孔扩散系数随着盐浓度的增加而增大,但当盐浓度增大到0.15 mol•L-1时又有所降低,表明存在着一个最佳的离子强度,使蛋白质的孔扩散系数最大.  相似文献   

16.
Adsorption of bovine serum albumin (BSA) onto positively charged core‐shell latex particles with a polystyrene core and a rich poly(N‐isopropylacrylamide) (NIPAM)) shell layer was investigated as a function of pH, ionic strength and temperature. Adsorption of BSA protein onto such cationic and thermosensitive particles was found negligible below the LCST of poly(NIPAM), whereas it was much higher above it. In addition, the pH and the salinity dependence of the adsorbed amount at the plateau reflected the role of electrostatic interactions. Protein adsorption behaviour was discussed by taking into account the changes in the interfacial properties of polymer particles (structure of the shell, hydrophilic–hydrophobic balance, charge density) versus temperature, suggesting that coulombic forces are mostly operating in this process. A desorption study showed that the BSA release efficiency was dependent upon the incubation time of the preliminary adsorbed step, and the effect of pH and ionic strength confirmed the contribution of electrostatic interactions. Copyright © 2004 Society of Chemical Industry  相似文献   

17.
A novel chitosan (Ch)-based polyampholyte hydrogel was prepared from Ch dissolved in a 1:1 (v/v) mixture of 10% aqueous acetic acid and N-methyl-2-pyrrolidinone (NMP) by simple crosslinking using 1,2,3,4-butanetetracarboxylic dianhydride (BTCA). The detailed structure of the hydrogel was determined via FTIR and solid-state 13C NMR spectroscopic analyses. The swelling behavior of the hydrogels was strongly dependent on the BTCA feed ratio, and the hydrogels exhibited a pH-responsive swelling ratio that was influenced by the presence of both cationic NH3+ and anionic COO? groups within their molecular structures. The Ch hydrogels also exhibited bovine serum albumin (BSA) adsorption capacity, which was maximal at pH 4.5, consistent with the isoelectric point of BSA (4.7). In addition, the BSA adsorption capacity of the hydrogel decreased with the increasing ionic strength of the adsorption medium, indicating that the capacity of the hydrogel to adsorb BSA is facilitated by hydrophobic as well as electrostatic interactions between the hydrogels and the BSA molecules. In addition, a high desorption ratio (89%) of BSA was achieved in aqueous solutions at pH 2.0.  相似文献   

18.
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.  相似文献   

19.
Using an environmental transmission electron microscope (ETEM), we show that a significant amount of water, far exceeding the multilayers caused by surface adsorption, is reversibly associated prior to deliquescence with substrate-supported NaCl particles (dry diameters of ~ 40 nm to 1.5 μ m; ~ 18°C). We hypothesize that the water is present as an aqueous solution containing dissolved Na and Cl ions. Water uptake occurs at relative humidities (RH) as low as 70%, and the resulting liquid layer coating the particles is stable over extended times if the RH is held constant. We exposed CaSO 4 and CaSO 4 · 2H 2 O particles to elevated RH values in the ETEM to show that chemically nonspecific condensation of gas-phase water on the TEM substrate does not explain our observations. Furthermore, damage to the NaCl surface induced by the electron beam and small fluctuations in RH do not seem to contribute to or otherwise affect water uptake. We have similar observations of water association for other alkali halide particles, including NaBr and CsCl, prior to deliquescence. To explain the observations, we derive the phase rule for this geometry and show that it allows for the coexistence of liquid, solid, and vapor for the binary NaCl/H 2 O system across a range of RH values. The derivation includes the effects of heterogeneous pressure because of the Laplace-Young relations for the subsystems. Furthermore, in view of the lever rule and the absence of similar observations for free-floating pure NaCl aerosol particles, we hypothesize that the surface energy necessary to support these effects is provided by sample-substrate interactions. Thus, the results of this study may be relevant to atmospheric systems in which soluble compounds are associated with insoluble materials.  相似文献   

20.
In the present study, a series of ionic poly(N-t-butylacrylamide-co-acrylamide) [P(NTBA-co-AAm)] hydrogels were synthesized by free-radical crosslinking copolymerization of N-t-butylacrylamide (NTBA) and acrylamide (AAm) monomers in fixed amount, but changing amount of maleic acid (MA) comonomer in methanol using N,N-methylene-bis-acrylamide (BAAm) as the crosslinker, ammonium persulfate (APS) as the initiator, and N,N,N′,N′-tetramethylethylenediamine (TEMED) as the activator. The swelling behavior of these hydrogels was analyzed in buffer solutions at various pHs. The prepared hydrogels also were investigated swelling-deswelling transition in water depending on the temperature. For the bovine serum albumin (BSA) adsorption, the effect of pH, temperature, initial protein concentration and adsorption rate were investigated. Maximum BSA adsorption was observed at pH 5.0 which is close to the isoelectric pH of BSA (pH 4.8). The highest adsorption rate was achieved in about 12 h. and also, maximum BSA adsorption was found at +5°C.  相似文献   

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