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Entrapment

Entrapment, also called inclusion, occlusion, and lattice entrapment, involves the formation of a highly cross-linked polymer network in the presence of an enzyme, so that the enzyme is trapped in interstitial spaces. Smaller species, such as substrates and products, freely diffuse through the polymer network, while the large [Pg.69]

The resulting cross-linked polyacrylamide possesses characteristics that are determined by the quantities of monomer and cross-linker used. The [monomer]/[cross-linker] ratio determines the pore size in which enzyme is entrapped. The total [monomer] + [cross-linker] quantities used will determine the so-called mechanical properties of the gel its stability and rigidity. [Pg.70]

For example, cholinesterase may be entrapped in a gel prepared from 5% crosslinker and 15% monomer in aqueous solution.21 Under these conditions, 56% of the total enzyme activity was retained. At higher total [monomer] + [cross-linker], the enzyme denatures, while higher [cross-linker] values yielded less entrapped enzyme. [Pg.70]

The entrapment process involves physically entrapping the enzyme with insoluble polymers of synthetic or natural origin. It is a type of gel entrapment in which the lipase is brought into a monomeric solution, which upon polymerization leads to its entrapment. By using this method, the lipase is kept free in solution however, it is also restricted by the polymer (Murty et al., 2002). The advantage of such a technique is that it is simple, the enzyme does not interact with the polymer, denaturation is avoided, and it has a high initial yield. However, the mass transfer limitation, in the form of internal diffusion resistance, is a problem, as the substrate/product diffusion rate across the membrane is a limiting factor (Villeneuve et al., 2000). [Pg.46]

Among the common matrices used for entrapment is a polyacrylamide gel that has been used with the extracellular lipase from Penicillium chrysogenum (Shafei and Allam, 2010). This gel is not suitable for use in food applications due to its toxicity (D Souza, 1999). [Pg.46]


Gel permeation chromatography, exclusion chromatography. gel filtration chromatography. A technique for separating the components of a mixture according to molecular volume differences. A porous solid phase (a polymer, molecular sieve) is used which can physically entrap small molecules in the pores whilst large molecules pass down the column more rapidly. A solvent pressure up to 1000 psi may be used. [Pg.98]

Thin films of fullerenes, which were deposited on an electrode surface via, for example, drop coating, were largely heterogeneous, due to the entrapping of solvent molecules into their domains. Consequently, their electrochemical behaviour displayed different degrees of reversibility and stability depending on the time of electrolysis and the... [Pg.2418]

False minima may entrap the unwary a structure may be mistaken for the ground state that does not represent the most stable conformer. If so, the calculated... [Pg.158]

An uneventful coupling of two hemispherical cavitand molecules — a tetrameth-anethiol and a tetrakis(chloromethyl)precursor (see p. 169) — yielded D.J. Cram s (1988) carcerand . ft entraps small molecules such as THF or DMF, cesium or chloride ions, or argon atoms as permanently imprisoned guests . Only water molecules are small enough to pass through the two small pores of this molecular (prison) cell. [Pg.356]

The stoichiometry must be exact. Coprecipitation by solid-solution formation, foreign ion entrapment, and adsorption are possible sources of error. [Pg.1166]

Fig. 3J4 Entrapment of mercury in a pore network. (Courtesy Androutsopoulos and Mann." )... Fig. 3J4 Entrapment of mercury in a pore network. (Courtesy Androutsopoulos and Mann." )...
Example of copredpitation (a) schematic of a chemically adsorbed inclusion or a physically adsorbed occlusion in a crystal lattice, where C and A represent the cation-anion pair comprising the analyte and the precipitant, and 0 is the impurity (b) schematic of an occlusion by entrapment of supernatant solution (c) surface adsorption of excess C. [Pg.239]

These ideas are readily applied to the mechanism described by reaction (5.F). To begin with, the rate at which ab links are formed is first order with respect to the concentration of entrapped pairs. In this sense the latter behaves as a reaction intermediate or transition state according to this mechanism. Therefore... [Pg.281]

These entrapped pairs, in turn, form at a rate given by the rate at which the two groups diffuse together minus the rate at which they either diffuse apart or are lost by reaction ... [Pg.281]

The concentration of entrapped pairs is assumed to exist at some stationary-state (subscript s) level in which the rates of formation and loss are equal. In this stationary state d[(-A + B-)] /dt = 0 and Eq. (5.6) becomes... [Pg.281]

In discussing mechanism (5.F) in the last chapter we noted that the entrapment of two reactive species in the same solvent cage may be considered a transition state in the reaction of these species. Reactions such as the thermal homolysis of peroxides and azo compounds result in the formation of two radicals already trapped together in a cage that promotes direct recombination, as with the 2-cyanopropyl radicals from 2,2 -azobisisobutyronitrile (AIBN),... [Pg.352]

Emulsion Adhesives. The most widely used emulsion-based adhesive is that based upon poly(vinyl acetate)—poly(vinyl alcohol) copolymers formed by free-radical polymerization in an emulsion system. Poly(vinyl alcohol) is typically formed by hydrolysis of the poly(vinyl acetate). The properties of the emulsion are derived from the polymer employed in the polymerization as weU as from the system used to emulsify the polymer in water. The emulsion is stabilized by a combination of a surfactant plus a coUoid protection system. The protective coUoids are similar to those used paint (qv) to stabilize latex. For poly(vinyl acetate), the protective coUoids are isolated from natural gums and ceUulosic resins (carboxymethylceUulose or hydroxyethjdceUulose). The hydroHzed polymer may also be used. The physical properties of the poly(vinyl acetate) polymer can be modified by changing the co-monomer used in the polymerization. Any material which is free-radically active and participates in an emulsion polymerization can be employed. Plasticizers (qv), tackifiers, viscosity modifiers, solvents (added to coalesce the emulsion particles), fillers, humectants, and other materials are often added to the adhesive to meet specifications for the intended appHcation. Because the presence of foam in the bond line could decrease performance of the adhesion joint, agents that control the amount of air entrapped in an adhesive bond must be added. Biocides are also necessary many of the materials that are used to stabilize poly(vinyl acetate) emulsions are natural products. Poly(vinyl acetate) adhesives known as "white glue" or "carpenter s glue" are available under a number of different trade names. AppHcations are found mosdy in the area of adhesion to paper and wood (see Vinyl polymers). [Pg.235]

Chemical Applications. Courtaulds has developed a series of acryHc-based fibers for controUed release of chemical reagents. The trade name of these fibers is Actipore. The reagents are entrapped within the fiber and slowly released at a rate dependent on the exact porosity of the fiber (102). [Pg.285]

Fibrillated Fibers. Instead of extmding cellulose acetate into a continuous fiber, discrete, pulp-like agglomerates of fine, individual fibrils, called fibrets or fibrids, can be produced by rapid precipitation with an attenuating coagulation fluid. The individual fibers have diameters of 0.5 to 5.0 ]lni and lengths of 20 to 200 )Jm (Fig. 10). The surface area of the fibrillated fibers are about 20 m /g, about 60—80 times that of standard textile fibers. These materials are very hydrophilic an 85% moisture content has the appearance of a dry soHd (72). One appHcation is in a paper stmcture where their fine fiber size and branched stmcture allows mechanical entrapment of small particles. The fibers can also be loaded with particles to enhance some desired performance such as enhanced opacity for papers. When filled with metal particles it was suggested they be used as a radar screen in aerial warfare (73). [Pg.297]

Froth flotation (qv) is a significant use of foam for physical separations. It is used to separate the more precious minerals from the waste rock extracted from mines. This method reHes on the different wetting properties typical for the different extracts. Usually, the waste rock is preferentially wet by water, whereas the more valuable minerals are typically hydrophobic. Thus the mixture of the two powders are immersed in water containing foam promoters. Also added are modifiers which help ensure that the surface of the waste rock is hydrophilic. Upon formation of a foam by bubbling air and by agitation, the waste rock remains in the water while the minerals go to the surface of the bubbles, and are entrapped in the foam. The foam rises, bringing... [Pg.431]

Pyridine herbicides are not strongly sorbed to soils and ate readily leached. The mobiUty of flutoxypyt [69377-81-7] has been found to decrease with increasing incubation time (399) this is attributed to entrapment of the herbicide within the soil organic matter. [Pg.53]

Functionalized conducting monomers can be deposited on electrode surfaces aiming for covalent attachment or entrapment of sensor components. Electrically conductive polymers (qv), eg, polypyrrole, polyaniline [25233-30-17, and polythiophene/23 2JJ-J4-j5y, can be formed at the anode by electrochemical polymerization. For integration of bioselective compounds or redox polymers into conductive polymers, functionalization of conductive polymer films, whether before or after polymerization, is essential. In Figure 7, a schematic representation of an amperomethc biosensor where the enzyme is covalendy bound to a functionalized conductive polymer, eg, P-amino (polypyrrole) or poly[A/-(4-aminophenyl)-2,2 -dithienyl]pyrrole, is shown. Entrapment of ferrocene-modified GOD within polypyrrole is shown in Figure 7. [Pg.46]

Fig. 8. Entrapment of mediator-modified enzymes within a conductive polymer film where ( ) represents the mediator ferrocene and (B) the active site... Fig. 8. Entrapment of mediator-modified enzymes within a conductive polymer film where ( ) represents the mediator ferrocene and (B) the active site...

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Active Re Clusters Entrapped in ZSM-5 Pores

Additives entrapment

Adhesive entrapment mechanism

Air Entrapment

Alkaline flooding entrapment

Atoms or Molecular Substances Entrapped by Cocondensation at the Colloidization Step

Benzoin Condensation with Entrapped Benzaldehyde Lyase

Binding Energy Entrapment

Biopolymer entrapment

Brachial Entrapment

Candida tropicalis entrapped

Capillary entrapment

Catalysis chemically entrapped catalysts

Catalyst entrapped

Catalysts entrapment

Catalysts entrapment chemical

Catalysts entrapment physical

Cell entrapment

Cell entrapment immobilized biocatalysts

Charge Polarization and Entrapment

Chemically Entrapped Catalysts

Compliance due to Entrapped Gas

Conducting polymer films entrapment

Cysteine entrapping

Deep Entrapment

Dense packed entrapment

Differential entrapment

Drain entrapment

Drug entrapment

Drug entrapped in liposomes

Drug-entrapment strategies, based

Drugs small molecule entrapment

Electroaffinity Modulation Valance Entrapment

Electrochemical entrapment

Electronic Origin Charge Entrapment and Polarization

Electrons Entrapment and Polarization

Enantiomers entrapment

Energy Entrapment

Entrapment Without Polarization

Entrapment alginate

Entrapment and Encapsulation

Entrapment and Polarization

Entrapment as a Pre-and Post-Immobilization Strategy

Entrapment carrageenan

Entrapment cross-section

Entrapment efficiency

Entrapment enzyme aggregates

Entrapment functionalization

Entrapment in Gel Matrixes

Entrapment medium

Entrapment membrane

Entrapment methods

Entrapment model

Entrapment of Probe Species

Entrapment of Proteins in Soybean

Entrapment of petroleum

Entrapment of platelet

Entrapment of proteins

Entrapment of rings

Entrapment polyacrylamide

Entrapment polyacrylate

Entrapment polymer network

Entrapment precipitation

Entrapment protein membrane

Entrapment salen ligands

Entrapment solution

Entrapment steric

Entrapment technique

Entrapment within electrochemically

Entrapment, biomaterials

Entrapment, free-energy

Entrapped air

Entrapped chemicals

Entrapped complexes

Entrapped dendrimers

Entrapped ethylene

Entrapped gas

Entrapped glucose oxidase

Entrapped materials, multiple

Entrapped materials, multiple emulsions

Entrapped porosity

Entrapped sol-gel complexes

Entrapped voids

Entrapped water

Entrapped water volume

Entrapping method

Entrapping molecules

Entrapping properties

Entrapping technology

Enzyme Immobilization and Entrapment

Enzyme biosensors physical entrapment

Enzyme by entrapment

Enzyme entrapment

Enzyme entrapped

Enzyme immobilization entrapment

Enzyme using entrapment technique

Enzymes immobilising entrapment method

Femoral Entrapment

Gel entrapment

Gel entrapped multistep

Gel entrapped multistep systems

Giant Phospholipid Vesicles Entrapping

Glucose entrapment

Gold nanoparticles dendrimer-entrapped

Grafting vs. Mechanical Entrapment

High entrapment efficiency

Hydrocarbon accumulation and entrapment in hydrodynamic sedimentary basins

Hydrocarbon accumulation and entrapment under hydrodynamic conditions

Hydrocarbon accumulation and entrapment under hydrostatic conditions

Hydrocarbon accumulation, entrapment and preservation

Hydrogel entrap enzymes

Hydrogel entrap particles

Hysteresis, entrapment, and contact angle

Immobilization entrapment

Immobilization techniques enzyme entrapment

Insect entrapment

Lattice-type entrapment

Lipase immobilization entrapment/encapsulation

Liposome entrapment

Liposome entrapment efficiency

Liposome vaccine entrapment

Liposomes large molecule entrapment

Liposomes small molecule entrapment

Materials and Modifiers Entrapped in Porous Matrices

Matrix entrapment

Mechanical entrapment

Mechanical entrapment of polymer

Mediator-modified enzymes, entrapment

Mesoporous enzyme entrapment

Metal zeolite-entrapped

Microbial physical entrapment

Microcapsule-type entrapment

Mold powder entrapment

Molecular physically entrapped (adsorbed

Molecules entrapment

Monolayer Skin Entrapment Without Polarization

Nerve Entrapment Syndromes

Oil entrapment

Oligonucleotides entrapment

Organic Steric Entrapment

Organometallic catalysts, entrapment

Pesticide matrix entrapment

Physical Entrapment of Proteins into Hydrogels General Principles and Release Mechanisms

Physical entrapment

Physical entrapment methods

Physical entrapment, enzyme stabilization

Physical entrapment, enzyme stabilization method

Physically Entrapped Catalysts

Plant cells entrapment

Polyacrylamide-entrapped cells

Polymer Entrapment

Popliteal arterial entrapment syndrome

Popliteal entrapment syndrome

Porphyrin entrapment

Post-entrapment modification of He and Ar isotopes

Protein entrapment

Protein entrapped

Quatum Entrapment with Polarization

Reverse micellar entrapment

Reversed micelle-entrapped colloidal

Saccharomyces cerevisiae entrapment

Silica-Entrapped Reactants

Silica-entrapped reagents

Silver atoms entrapped

Sol-gel entrapment

Sol-gel entrapped catalysts

Substances Adsorbed or Entrapped at the Gelation Step

Surface Skin-Resolved Quantum Entrapment

TEMPO silica-entrapped

The Entrapped Water Volume

Thiol, silica-entrapped

Thrombus entrapment

Two-Stage Approach to Biopolymer Entrapment

Vesicles entrapment

Voids mechanical entrapment

Water entrapment

Water entrapment hypothesis

Workfunction Polarization or Entrapment

Zeolite-Entrapped Metal Complexes

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