Entrapment method

The entrapment method is based on confining the enzyme within the lattice of a polymeric matrix. Polyacrylamide gels have successfully yielded stable enzyme films with a high retention of activity... 

Agents Entrapment method Suggested action against target/disease... 

This sol-gel procedure is an elaboration on well established entrapment methods [29], but with the added advantage of stability and better flow properties. Interestingly, none of the examples presented thus far demonstrate competitive behavior between multiple ligands (i.e. displacement) in the FAC analysis of trimethoprim and pyrimethamine a reversed order of elution based on is described, but this could simply be due to the shift towards an on-rate limited situation for higher affinity compounds, as described earlier. Erosion of dynamic competition between ligands could occur if the sol-gel allows convective mixing of the entrapped protein however the bimodal pore structure of these materials would... 

When entrapment methods are being used for heterogenization, the size of the metal complex is more important than the specific adsorptive interaction. There are two different preparation strategies. The first is based on building up catalysts in well-defined cages of porous supports. This approach is also called the ship in a bottle method [29]. The other approach is to build up a polymer network around a preformed catalyst. 

The gel volume is dependent on the solvent composition. When the solvent composition in the gel is changed by enzymatic reaction, the gel is expected to undergo the volume phase transition. This is another approach of chemicals-induced volume phase transition [22]. Rabbit liver esterase was immobilized in the gel by an entrapped method. The esterase catalyses the following reaction. 

When immobilizing biocatalysts within polymer gels using physical entrapment methods, we may take advantage of the great resistance to the diffusion of macromolecular substances due to the gel porosity. However, this limited diffusion within the gel phase also causes a reduced mass transfer rate for low... 

However, Yokoyama et al. (1994) reported that a ratio between the chemically conjugated and physically entrapped ADR (i.e., DOX) was not determined, and considerable amounts of adriamycin derivatives formed and were incorporated in the micelles. Yokoyama et al. (1998) quantitatively measured the ADR incorporated in the inner core using the improved synthetic method, and analyzed the effects of the ADR contents (both by chemical conjugation and physical entrapment) on micelle stability andn vivo antitumor activity. The copolymer used by Yokoyama et al. (1998) was polyethylene glycol)-fepoly(aspartic acid) block copolymer (PB P(Asp)). The chemical conjugation and physical entrapment methods can be referred to in the earlier section of preparation of polymeric micelles. 

Figure 17.3, the reactant was fed into the solvent, while the product was extracted in water. The lipase was immobilized by entrapment method on asymmetric PAN hollow-fiber membranes. The process was run for several years with modules for the production plant of 60 m2 of active membrane area. 

The entrapment method of immobilization is based on the localization of an enzyme within a polymer membrane matrix. It is done in such a way as to retain biocatalyst, while allowing penetration of substrate. 

Table 1. Various factors affecting the degree of immobilization in the physical entrapping method...

In this polymerization, the biofunctional component (enzyme) can be concentrated in an interfacial area between the frozen ice crystal and the supercooled monomer phase, and immobilized by molecular entanglement between the enzyme and polymer molecules. This is a different procedure for fixation from the usual entrapping method with a crosslinked structure in a gel. Therefore, we may call this procedure the adhesion-method to distinguish it from the usual entrapping. This term was extended to cover the use of the usual synthetic polymers including hydrophobic polymers as the supports. One of the characteristic properties of products obtained in this way was that there is a maximum activity at a certain monomer concentration. The maximum activity is observed when the increased inner surface area is balanced by the increased leakage of enzyme and these occur with a decrease of monomer concentration. Immobilization by physical entrapping was also studied by Rosiak [26], Carenza [27] and Ha [28]. 

The main disadvantage is that entrapping methods can often be used for the conversion of low-molccular-weight substrates only, and there is always the possibility for losses of the enzyme to the surrounding environment. 

Entrapment methods have been used almost exclusively to immobilize plant cells (17). They can be classified into three general groups (24,25) a. gel formation by ionic crosslinking of a charged polymer (ionotropic) b. gel formation by cooling of a heated polymer (thermal), and c. gel formation by chemical reaction (cross-linking, radical polymerization). 

No chemical modification of the enzyme is required. The methods utilize gender conditions as compared to covalent binding and entrapment methods. Entrapment in alginate or K-carragenans is a fairly gende... 

Entrapment methods of immobilization of bioreceptors utilized the lattice structure of particular base material. They include such methods as entrapment behind the membrane, covering the active surface of biosensors, entrapment within a self-assembled monolayers on the biosensor surface, as well as on freestanding or supported bilayer lipid membranes, and also entrapment within a polymeric matrix membranes, or within bulk material of sensor. All these mentioned methods are widely employed in design of biosensors. The essential condition of success of these methods of immobilization is preservation of sufficient mobility of substrate or products of biochemical reaction, involved in sensing mechanism, as matrix may act as a barrier to mass transfer with significant implications for... 

Unfortunately, there are few studies available in which a systematic comparison of the encap-snlation efficiency depending on the entrapment method has been reported. Therefore, experiments... 

Electrochemical polymerization is another entrapment method which can be used to immobilize a detector molecule into a conductive, redox, or insulating film on a transducer (see chapter 6). For example, glucose oxidase (GOD) was immobilized into a poly(m-phenylenediamine) film formed by potentiostatic electropolymerization of the monomer on gold-coated glass slides... 

SOFC POWDER SYNTHESIS BY THE ORGANIC STERIC ENTRAPMENT METHOD... 

THE ORGANIC-INORGANIC STERIC ENTRAPMENT METHOD OF POWDER SYNTHESIS... 

Since complicated multicomponent ceramic materials with precise levels of doping are required for some of the new materials that show promise in solid oxide fuel cells, we aim to use the relatively low-cost, simple steric entrapment method to synthesize several solid oxide fuel cell materials, and evaluate some of their characteristics. We have selected lanthanum gallates doped with strontium and magnesium, samarium doped ceria and a promising non-stoichoimetric composition composed of strontium iron and cobalt. 

Rosczyk B.R., Kriven W.M., Mason T.O., Solid oxide fuel cell materials synthesized by an organic steric entrapment method, 2003, V.24, N.3, p.287-292. 

The viability of the yeast cells, and thus the reduced toxicity of the entrapment method, can be demonstrated by cell growth In the matrix, which gives rise to a corresponding activity Increase for ethanol production from glucose (J) This behavior Is shown In Figure A. The factor of activity Increase compared to the Initial value Increases with decreasing Initial loading however. 

Two general types of methods are available for estimating human exposure to pesticides. First, direct entrapment methods involve the use of some mechanism to entrap the toxic material as it comes in contact with the person during an exposure period. The amount of entrapped toxicant, as determined by chemical analysis, is then a direct measure of the particular exposure under study. Further calculations using the kinetics of dermal absorption for the compound and formulation under study are required to arrive at the actual ateorbed dose. For the oral and inhalation routes, exposure and absorbed dose are more closely equivalent than for the dermal route. However, for precise data, absorption must be taken into account for these routes, also. Second, indirect methods are based on measurement of some effect of the compound on the exposed individual (such as blood... 

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