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1.
Purification of recombinant protein A by aqueous two-phase extraction integrated with affinity precipitation 总被引:3,自引:0,他引:3
Aqueous two-phase extraction incorporated affinity precipitation was examined as a technique for protein purification. An enteric coating polymer, Eudragit S100, was employed as a ligand carrier. Eudragit was specifically partitioned to the top phase in the aqueous two-phase systems. For application of this method to purification of recombinant protein A using human IgG coupled to Eudragit in an aqueous two-phase system, 80% of protein A added was recovered with 81% purity. The purity was enhanced 26-fold by thid method. The IgG-Eudragit could be used repeatedly for the purification process. This seperation method should be applicable to industrial-scale purification as a new purification procedure combining the advantages and compensating for the disadvantages of the aqueous two-phase method and affinity precipitation method. (c) 1992 John Wiley & Sons, Inc. 相似文献
2.
《Biocatalysis and Biotransformation》2013,31(5-6):313-319
AbstractTo prepare a smart biocatalyst, cellulase was immobilized on the reversibly soluble matrix Eudragit L-100 by non-covalent and covalent methods. Covalent immobilization using carbodiimide coupling exhibited superior enzyme loading and reusability compared with non-covalent immobilization, and the covalent loading was increased by almost 20% through the addition of N-hydroxysuccinimide. The temperature optimum of the cellulase was not improved apparently by immobilization but the pH optimum increased from 4.75 to 5.25. Immobilized cellulase was more active than free cellulase above pH 5.0. Immobilized cellulase was more stable than free cellulase during storage at 4°C, room temperature and 50°C. Km values of immobilized and free cellulase were 85.55 and 73.84 g L?1, respectively. About 50% productivity was retained after five cycles for hydrolysis of steam-exploded straw. 相似文献
3.
Yuanyuan Yu Jiugang Yuan Qiang Wang Xuerong Fan Ping Wang Xuejiao Sun 《Engineering in Life Science》2013,13(2):194-200
Cellulases can penetrate into the fiber, causing tensile strength loss of the cellulosic fibers or fabrics. To minimize the tensile strength loss, we have immobilized cellulases on Eudragit S‐100. The characteristics of covalent Eudragit cellulase were evaluated using gel filtration analysis and UV spectra. Gel filtration analysis revealed that the cellulases were covalently bound to the polymer. Covalent Eudragit cellulase was loaded with the enzyme of about 40% and had a relative activity about 80% at a Eudragit S‐100 concentration of 15 g/L. When cellulase is bound to the polymer, the solubility profile becomes similar to the one of Eudragit. In addition, the effects of the enzyme on the cotton yarns and fabric using cellulases have been investigated. Native and immobilized cellulases caused improvements in whiteness and wrinkle recovery angle of the fabric in comparison to the control samples. The bending stiffness results show that native and immobilized cellulase treated cotton fabric has an improved softness than the control samples. It was found that using the immobilized cellulase reduced the weight and tensile strength, because the hydrolytic attack is only limited to the surfaces of cotton fibers. 相似文献
4.
The purpose of this research was to investigate the effects of different concentrations of polymer and sucrose stearate, aluminum
tristearate as dispersing agents on microsphere properties and performance. The yield values of microspheres were over the
78%, and the encapsulation efficiencies were found to be ∼735. Particle sizes of microspheres prepared with aluminum tristearate
were between 76 and 448 μm, while that of the microspheres containing sucrose stearate were between 521 and 2000 μm. Morphological
and physicochemical properties of microspheres were investigated by scanning electron micrography and differential scanning
calorimetry (DSC). DSC analysis indicated that verapamil hydrochloride formed a solid solution with acrylic polymers. In vitro
release studies were performed using the flow-through cell method. While ∼80% of drug was released from the microspheres containing
aluminum tristearate in 480 minutes, the same amount of drug was released from microspheres containing sucrose stearate in
only 60 minutes. Chemical structures and concentrations of the dispersing agents were clearly effective on the physical properties
of microspheres and their drug-release characteristics.
Published: February 24, 2006 相似文献
5.
Preparation and characterization of Eudragit Retard nanosuspensions for the ocular delivery of cloricromene 总被引:1,自引:0,他引:1
Pignatello R Ricupero N Bucolo C Maugeri F Maltese A Puglisi G 《AAPS PharmSciTech》2006,7(1):E192-E198
The purpose of this study was to improve the stability of cloricromene (AD6) in ophthalmic formulations and its drug availability
at the ocular level. To this end, AD6-loaded polymeric nanoparticle suspensions were made using inert polymer resins (Eudragit
RS100 and RL100). We modified the quasi-emulsion solvent diffusion technique by varying some formulation parameters (the drug-to-polymer
ratio, the total drug and polymer amount, and the stirring speed). The chemical stability of AD6 in the nanosuspensions was
assessed by preparing some formulations using (unbuffered) isotonic saline or a pH 7 phosphate buffer solution as the dispersing
medium. The formulations were stored at 4°C, and the rate of degradation of AD6 was followed by high performance liquid chromatography
(HPLC). The obtained nanosuspensions showed mean sizes and a positive surface charge (ζ-potential) that make them suitable
for an ophthalmic application; these properties were maintained upon storage at 4°C for several months. In vitro dissolution
tests confirmed a modified release of the drug from the polymer matrixes. Nanosuspensions prepared with saline solution and
no or lower amounts of surfactant (Tween 80) showed an enhanced stability of the ester drug for several months, with respect
to an AD6 aqueous solution. Based on the tecnological results, AD6-loaded Eudragit Retard nanoparticle suspensions appear
to, offer promise as a means to improving the shelf life and bioavailability of this drug after ophthalmic application.
Published: March 24, 2006 相似文献
6.
Nguyen CA Konan-Kouakou YN Allémann E Doelker E Quintanar-Guerrero D Fessi H Gurny R 《AAPS PharmSciTech》2006,7(3):E54-E60
The aim of the present study was to prepare surfactant-free pseudolatexes of various methacrylic acid copolymers. These aqueous
colloidal dispersions of polymeric materials for oral administration are intended for film coating of solid dosage forms or
for direct manufacturing of manoparticles. Nanoparticulate dispersions were produced by an emulsification-diffusion method
involving the use of partially water-miscible solvents and the mutual saturation of the aqueous and organic phases prior to
the emulsification in order to reduce the initial thermodynamic instability of the emulsion. Because of the self-emulsifying
properties of the methacrylic acid copolymers, it was possible to prepare aqueous dispersions of colloidal size containing
up to 30% wt/vol of Eudragit RL, RS, and E using 2-butanone or methyl acetate as partially water-miscible solvents, but without
any surfactant. However, in the case of the cationic Eudragit E, protonation of the tertiary amine groups by acidification
of the aqueous phase was necessary to improve the emulsion stability in the absence of surfactant and subsequently to prevent
droplet coalescence during evaporation. In addition, a pseudolatex of Eudragit E was used to validate the coating properties
of the formulation for solid dosage forms. Film-coated tablets of quinidine sulfate showed a transparent glossy continuous
film that was firmly attached to the tablet. The dissolution profile of quinidine sulfate from the tablets coated with the
Eudragit E pseudolatex was comparable to that of tablets coated with an acetonic solution of Eudragit E. Furthermore, both
types of coating ensured similar taste masking. The emulsification-evaporation method used was shown to be appropriate for
the preparation of surfactant-free colloidal dispersions of the 3 types of preformed methacrylic acid copolymers; the dispersions
can subsequently be used for film coating of solid dosage forms.
Published: July 28, 2006 相似文献
7.
Yeon-Kye Kim 《Carbohydrate research》2010,345(8):1065-1007
Waxy maize starch (100% amylopectin) granules were modified by reaction of the granules with glucoamylase in a minimum amount of water to give 29% (w/w) d-glucose inside the granules [Kim, Y.-K.; Robyt, J. F. Carbohydr. Res.1999, 318, 129−134]. These granules were made into beads by dropping an ethanol slurry of starch and different amounts of Eudragit L100-55 in a constant ratio of 100:1 from a pipette onto Whatman 3MM filter paper. The starch beads were air dried and then repeatedly sprayed 0-12 times with 2.0% (w/v) Eudragit L100-55 in ethanol, with drying between each spraying, to coat the surface of the starch beads, giving different amounts of Eudragit L100-55 coating. Seven different kinds of beads, with different amounts of Eudragit L100-55 binding and coating agent, were obtained. The rates of release of d-glucose into water from the seven kinds of beads were inversely proportional to the amount of binding and coating agent. Bead type I, which was without any binding and coating gave a fast 100% release of d-glucose in 30 min. Beads II and III also gave a fast 100% release in 60 min and 90 min, respectively. Bead IV gave a near linear release of 97% d-glucose in 150 min; Bead V gave a 50% release in 120 min followed by the remaining 50% in 60 min; and Beads VI and VII gave a slow release of 10% and 4%, respectively, from 0 to 120 min, followed by a rapid 100% release from 120 to 180 min. 相似文献
8.
Summary Xylanase from Scytalidium thermophilum was immobilized on Eudragit L-100, a pH sensitive copolymer of methacrylic acid and methyl methacrylate. The enzyme was non-covalently
immobilized and the system expressed 70% xylanase activity. The immobilized preparation had broader optimum temperature of
activity between 55 and 65 °C as compared to 65 °C in case of free enzyme and broader optimum pH between 6.0 and 7.0 as compared
to 6.5 in case of free enzyme. Immobilization increased the t1/2 of enzyme at 60 °C from 15 to 30 min with a stabilization factor of 2. The Km and Vmax values for the immobilized and free xylanase were 0.5% xylan and 0.89 μmol/ml/min and 0.35% xylan and 1.01 μmol/ml/min respectively. An Arrhenius plot showed an increased value of activation energy for immobilized xylanase (227 kcal/mol)
as compared to free xylanase (210 kcal/mol) confirming the higher temperature stability of the free enzyme. Enzymatic saccharification
of xylan was also improved by xylanase immobilization. 相似文献
9.
Golam Kibria Monzurul Amin Roni Mohammad Shahriarul Absar Reza-ul Jalil 《AAPS PharmSciTech》2008,9(4):1240-1246
The present study was designed to investigate the effect of two plasticizers, i.e., triethyl citrate (TEC) and polyethylene
glycol 6000 (PEG 6000) on the in vitro release kinetics of diclofenac sodium from sustained-release pellets. Ammonio methacrylate copolymer type B (Eudragit RS
30 D) is used as the release-retarding polymer. Both plasticizers were used at 10% and 15% (w/w) of Eudragit RS 30 D. Pellets were prepared by powder layering technology and coated with Eudragit RS 30 D by air suspension
technique. Thermal properties of drug and drug-loaded beads were studied using differential scanning calorimeter (DSC). DSC
thermogram represented the identity of raw materials and exhibited no interaction or complexation between the active and excipients
used in the pelletization process. Dissolution study was performed by using USP apparatus 1. No significant difference was
observed among the physical properties of the coated pellets of different batches. When dissolution was performed as pure
drug, about 8.22% and 90% drug was dissolved at 2 h in 0.1 N HCl and at 30 min in buffer (pH 6.8), respectively. From all
formulations, the release of drug in acid media was very negligible (maximum 1.8 ± 0.08% at 2 h) but in buffer only 12% and
30% drug was released at 10 h from coated pellets containing TEC and PEG 6000, respectively, indicating that Eudragit RS 30
D significantly retards the drug release rate and that drug release was varied according to the type and amount of plasticizers
used. The amount of TEC in coating formulation significantly effected drug release (p < 0.001), but the effect of PEG 6000 was not significant. Formulations containing PEG 6000 released more drug (98.35 ± 2.35%)
than TEC (68.01 ± 1.04%) after 24 h. Different kinetic models like zero order, first order, and Higuchi were used for fitting
drug release pattern. Zero order model fitted best for diclofenac release in all formulations. Drug release mechanism was
derived with Korsmeyer equation. 相似文献
10.
The aim of this study was to investigate the effect of Eudragit RS 30D, talc, and verapamil hydrochloride on dissolution and mechanical properties of beads coated with "drug-layered matrices". This was accomplished with the aid of a three-factor multiple-level factorial design using percent drug release in 1 and 2 h, T(50), tensile strength, brittleness, stiffness and toughness as the responses. Beads were coated in a fluidized-bed coating unit. Surface morphology and mechanical properties were evaluated by surface profilometry and texture analysis, respectively. No cracks, flaws and fissures were observed on the surfaces. The mechanical properties were dependent on the talc/polymer ratio. The release of verapamil from the beads was influenced by matrix components. Increasing the level of both talc and Eudragit decreased the percent drug released from 67% to 4.8% and from 80.7% to 6.7% in 1 and 2 h, respectively, and increased T(50) from 0.8 to 25.7 h. It was concluded that beads could be efficiently coated with "drug-layered matrices". The release of drug, however, depends on a balance between the levels of drug, talc, and polymer, whereby desired dissolution and mechanical properties could be controlled by the talc/polymer ratio and the level of drug loading. 相似文献