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排序方式: 共有392条查询结果,搜索用时 15 毫秒
91.
Harvey SD Mong GM Ozanich RM McLean JS Goodwin SM Valentine NB Fredrickson JK 《Analytical and bioanalytical chemistry》2006,386(2):211-219
A novel, affinity-augmented, bacterial spore-imprinted, bead material was synthesized, based on a procedure developed for
vegetative bacteria. The imprinted beads were intended as a front-end spore capture/concentration stage of an integrated biological
detection system. Our approach involved embedding bead surfaces with Bacillus thuringiensis kurstaki (Bt) spores (as a surrogate for Bacillus anthracis) during synthesis. Subsequent steps involved lithographic deactivation using a perfluoroether; spore removal to create imprint
sites; and coating imprints with the lectin, concanavalin A, to provide general affinity. The synthesis of the intended material
with the desired imprints was verified by scanning electron and confocal laser-scanning microscopy. The material was evaluated
using spore-binding assays with either Bt or Bacillus subtilis (Bs) spores. The binding assays indicated strong spore-binding capability and a robust imprinting effect that accounted for 25%
additional binding over non-imprinted controls. The binding assay results also indicated that further refinement of the surface
deactivation procedure would enhance the performance of the imprinted substrate. 相似文献
92.
Synthetic materials capable of recognizing proteins are important in separation, biosensors and biomaterials. In this study,
bovine serum albumin-imprinted soft-wet polyacrylamide gel beads were prepared via inverse-phase suspension polymerization,
using acrylamide and N,N′-methylene diacrylamide as polymeric matrix components and methacrylic acid as functional monomer. The adsorption study showed,
through the imprinting process, that the imprinted gel beads had much higher adsorption capacity than the nonimprinted gel
beads, and that the matching of the surface zeta-potential between the templates and the imprinted gel beads can enhance the
imprinting effect. Adsorption kinetics indicated that the adsorption process could be described as an apparent first-order
kinetic process for the gel beads. From the adsorption isotherm curve, we found that the adsorption of the imprinted gel beads
was in agreement with the Langmuir adsorption model. Moreover, selectivity testing of the imprinted gel beads showed that
imprinted gel beads exhibited good recognition for BSA as compared to the control protein. We speculate that the formation
of complementary shapes and multiple-point electrostatic interactions between the imprinting cavities and the template proteins
are the two factors that lead to the imprinting effect.
相似文献
93.
A technique for separating and detecting enzyme inhibitors was developed using CE with an enzyme microreactor. The on‐column enzyme microreactor was constructed using NdFeB magnet(s) to immobilize alkaline phosphatase‐coated superparamagnetic beads (2.8 μm diameter) inside a capillary before the detection window. Enzyme inhibition assays were performed by injecting a plug of inhibitor into a capillary filled with the substrate, AttoPhos. Product generated in the enzyme microreactor was detected by LIF. Inhibitor zones electrophoresed through the capillary, passed through the enzyme microreactor, and were observed as negative peaks due to decreased product formation. The goal of this study was to improve peak capacities for inhibitor separations relative to previous studies, which combined continuous engagement electrophoretically mediated microanalysis and transient engagement electrophoretically mediated microanalysis to study enzyme inhibition. The effects of electric field strength, bead injection time and inhibitor concentrations on peak capacity and peak width were investigated. Peak capacities were increased to ≥20 under optimal conditions of electric field strength and bead injection time for inhibition assays with arsenate and theophylline. Five reversible inhibitors of alkaline phosphatase (theophylline, vanadate, arsenate, L ‐tryptophan and tungstate) were separated and detected to demonstrate the ability of this technique to analyze complex inhibitor mixtures. 相似文献
94.
Francisco Barahona Esther Turiel Peter A. G. Cormack Antonio Martín‐Esteban 《Journal of polymer science. Part A, Polymer chemistry》2010,48(5):1058-1066
In this work, two different surface imprinting formats have been evaluated using thiabendazole (TBZ) as model template. The first format is a thin film of molecularly imprinted polymer (MIP) grafted from preformed silica particles using an immobilized iniferter‐type initiator (inif‐MIP). The second format is molecularly imprinted polymer microspheres with narrow particle size distribution and core‐shell morphology prepared by precipitation polymerization in a two‐step procedure. For the latter format, polymer microspheres (the core particles) were obtained by precipitation polymerization of divinylbenzene‐80 (DVB‐80) in acetonitrile. Thereafter, the core particles were used as seed particles in the synthesis of MIP shells by copolymerization of DVB‐80 and methacrylic acid in the presence of TBZ in a mixed solvent porogen (acetonitrile/toluene). The materials were characterized by elemental microanalysis, nitrogen sorption porosimetry and scanning (and transmission) electron microscopy. Thereafter, the imprinted materials were assessed as stationary phases in liquid chromatography. From this study it can be concluded that grafted MIP beads can be obtained in a simple and direct manner, consuming only a fraction of the reagents used typically to prepare imprinted particles from a monolithic imprinted polymer. Such materials can be used in the development of in‐line molecularly imprinted solid‐phase extraction methods. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1058–1066, 2010 相似文献
95.
In most of the currently developed electrochemical DNA hybridization sensors short single-stranded probe DNA is immobilized on an electrode and both the hybridization and detection steps are carried out on the electrode surface. Here we use a new technology in which DNA hybridization is performed on commercially available magnetic beads and detection on solid electrodes. Paramagnetic Dynabeads Oligo(dT)25 (DBT) with covalently bound (dT)25 probe are used for the hybridization with target DNA containing adenine stretches. Target DNA is modified with osmium tetroxide,2,2′-bipyridine (Os,bipy) and the immunogenic DNA-Os,bipy adduct is determined by the enzyme-linked immunoassay with electrochemical detection. Electroinactive 1-naphthyl phosphate is used as a substrate and the electroactive product (1-naphthol) is measured on the carbon electrodes. Alternatively Os,bipy-modified target DNA can be determined directly by measuring the osmium signal on the pyrolytic graphite electrode (PGE). A comparison between determinations of the 67-mer oligodeoxynucleotide on carbon electrodes using (a) the guanine oxidation signal, (b) direct determination of the DNA-Os,bipy adduct and (c) its electrochemical immunoassay showed immunoassay to be the most sensitive method. In combination with DBT, the DNA hybridization of long target deoxyoligonucleotides (such as 67- and 97-mers) and a DNA PCR product (226-base pairs) have been detected by immunoassay at high sensitivity and specificity. 相似文献
96.
Q. Ching Wang Frantiek vec Jean M. J. Frchet 《Journal of polymer science. Part A, Polymer chemistry》1994,32(13):2577-2588
The porous structure of monodisperse macroporous beads can be controlled by using soluble polymers with well-defined structural characteristics as part of the porogenic mixture. In general, the use of linear polystyrene as a porogen in the preparation of poly (styrene-co-divinylbenzene) beads shifts the pore size distribution towards larger pores. While a direct correlation between pore size and molecular weight of the porogen has been established, the chemical composition of the polymer porogen has no effect on the porous and chromatographic properties of the beads. These findings suggest that the average molar volume of the porogenic system is important while the miscibility of the polymer porogen with the crosslinked polymer that is formed is of little relevance. © 1994 John Wiley & Sons, Inc. 相似文献
97.
Agarose acrobeads were produced by encapsulating polyacrolein microspheres (acrobeads) of 0.2 μm average diameter within an
agarose matrix. Crosslinked agarose acrobeads of diameters ranging from 0.5 to 0.8 mm were found to be optimal spheres for
specific hemoperfusion purposes. Agarose provides the biocompatibility and mechanical strength of the agarose acrobeads. Acrobeads
contain a high aldehyde-group content through which various amino ligands, i.e., proteins, antigens, antibodies, enzymes,
and so on, can be covalently bound in a single step under physiological pH (or other pH). Thus, antibodies, antigens, or toxic
materials may be directly removed from whole blood by hemoperfusion. During in vitro and in vivo hemoperfusion trials, the
content of erythrocytes, leukocytes, and thrombocytes was essentially unaltered. Likewise, a battery of the soluble blood
components (Cl-, K+, Na+, Ca2+, PO
4
-
), total proteins, albumin, and C
4
′
component of the complement cascade, as well as the enzymes SGOT, LDH, and alkaline phosphatase, remained constant within
narrow limits during the hemoperfusion procedure. The chemical and physical structure of the beads is stable; neither acrolein
nor bead fragments were detected in hemoperfusion trials. Similarly, leakage of antibody bound to the agarose acrobeads into
the blood is insignificant.
Thus far, we have demonstrated the efficacy of the crosslinked agarose acrobeads for extracorporeal removal of “unwanted”
substances from whole blood in the following systems: (a) removal of specific antigens (digoxin or paraquat removal with antidigoxin
or antiparaquat antibodies bound to the acrobeads, respectively), (b) removal of specific antibody (antiBSA) removal with
BSA bound to the beads), (c) removal of immune complexes (BSA-antiBSA complex removal with C1q bound to acrobeads), and (d)
removal of specific metals (removal of iron with deferoxamine bound to the agarose acrobeads). 相似文献
98.
A procedure is described for the immobilization of benzylpenicillin acylase from Escherichia coli within uniformly spherical, porous polyacrylamide gel beads. Aqueous solutions of the enzyme and sodium alginate and of acrylamide monomer, N,N'-methylene-bis-acrylamide, N,N,N,N'-tetramethylethylenediamine (TEMED) and sodium alginate are cooled separately, mixed, and dropped immediately into ice-cold, buffered calcium formate solution, pH 8.5, to give calcium alginate-coated beads. The beads are left for 30-60 min in the cold calcium formate solution for polyacrylamide gel formation. The beads are then treated with a solution of glutaraldehyde and the calcium alginate subsequently leached out with a solution of potassium phosphate. Modification of the native enzyme with glutaraldehyde results in a slight enhancement in the rate of hydrolysis of benzylpenicillin at pH 7.8 and 0.05M substrate concentration. The enzyme entrapped in porous polyacrylamide gel beads shows no measurable diffusional limitation in stirred reactors, catalyzing the hydrolysis of the substrate at a rate comparable to that of the glutaraldehyde-modified native enzyme. The immobilized enzyme preparation has been used in batch mode over 90 cycles without any apparent loss in hydrolytic activity. 相似文献
99.
Miroslav Petro Frantisek Svec Jean M. J. Frchet Shah A. Haque Hsien C. Wang 《Journal of polymer science. Part A, Polymer chemistry》1997,35(7):1173-1180
High-performance liquid chromatography (HPLC) has been used to complement size-exclusion (gel permeation) chromatography (SEC) for the characterization of functional polymers. Whereas SEC is unable to detect compositional changes, HPLC in an appropriate interacting medium can provide detailed information on compositional changes occurring during chemical modification of a polymer. The method has been demonstrated using a normal-phase column consisting of porous monodisperse 10 μm poly(2,3-dihydroxypropyl methacrylate-co-ethylene dimethacrylate) beads that have a homogeneous coverage of aliphatic hydroxyl groups for the analysis of brominated poly(isobutylene-co-4-methylstyrene). Differences of well below 1 mol % of bromomethylstyrene units are easily detected and quantified. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1173–1180, 1997 相似文献
100.