Immobilization efficiency

Figure 15.4(A) shows the effect of the R = Zn2+/Al3+ ratio, which determines the charge density of the LDH layer, on the Freundlich adsorption isotherms. K values are far higher than those measured for smectite or other inorganic matrices. The increase in Kf with the charge density (Kf= 215, 228, 325mg/g, respectively, for R = 4, 3 and 2) is supported by a mechanism of adsorption based on an anion exchange reaction. The desorption isotherms confirm that urease is chemically adsorbed by the LDH surface. The aggregation of the LDH platelets can affect noticeably their adsorption capacity for enzymes and the preparation of LDH adsorbant appears to be a determinant step for the immobilization efficiency. [ZnRAl]-urease hybrid LDH was also prepared by coprecipitation with R = 2, 3 and 4 and Q= urease/ZnRAl from 1 /3 up to 2.5. For Q < 1.0,100 % of the urease is retained by the LDH matrix whatever the R value while for higher Q values an increase in the enzyme/LDH weight ratio leads to a decrease in the percentage of the immobilized amount.

While immobilization and detection are important features, the choice of a suitable electrochemical substrate is also of great significance in determining the overall performance of the analytical electrochemical-based device, especially regarding the immobilization efficiency of DNA. 

Niemeyer CM, Boldt L, Ceyhan B, Blohm D. DNA-Directed immobilization Efficient, reversible, and site-selective surface binding of proteins by means of covalent DNA-streptavidin conjugates. Anal Biochem 1999 268(1) 54—63. 

Undoubtedly, the best immobilized complex attained was Dowex-lX4-200/invertase, because all its immobilization efficiency parameters (AI, IC, and protein retention) were equal to 100% (Table 1). Therefore, this complex was chosen for characterization assay purposes. 

Immobilization efficiency describes the percent of enzyme activity that is observed ... 

Two methods for the covalent immobilization of single-stranded DNA onto fused silica optical fibres using various linkers for the development of biosensors were reported by Krull and co-workers [22]. One method involved a hydrophobic and the other a hydrophilic spacer arm and it was determined which linker would provide the best immobilization efficiency, hybridization kinetics, and minimal non-specific adsorption to the surface. 

Nitrocellulose Hi-Flow plus membrane is often used widely. Nitrocellulose membranes are completely neutral, and their binding properties are independent of the pH of the immobilization solution (although pH can have an effect on both the solubility and immobilization efficiency of a particular protein). The immobilization buffer with pH 7.0-7.2 is chosen. Sometimes the surfactants and detergents such as Tween-20 and Triton-XlOO in very low concentration are added in the buffer to reduce the background and nonspecific binding. 

Recently, the functionalization of clays has been used to increase the immobilization efficiency of enzymes and other biomolecules [63]. The clay surface may be modified through reactions with various functional groups, such as thiol,... 

Fig. 2 The effects of recirculation flow rate on cell immobilization efficiency in a packed-bed bioreactor. Cell density=50 g/L...

In our study (6), porcine pancreas lipase (PPL) immobilized on silica particles (narrow distributed micron particles) was employed for ring-opening polymerization of TMC. No evidence of decarboxylation occurring during the polymerization. The results showed that silica microparticles improved immobilization efficiency much more. The most preferable polymerization temperature of TMC was 100 °C during 24h polymerization. The M of the resulting polymers was significantly increased compared with that catalyzed by... 

Candida molischiana 35M5N p-glucosidase was immoblized to Duolite A-568 resin with a very high immobilization efficiency (86%) [4]. The immobilization of the P-glucosidase permitts the obtention of a biocatalyst of potential interest for the control of organoleptic properties wine. Moreover, the industrial use of immobilized enzyme is an evident confirmation that the costs of production are smaller than in convential processes. The most important benefit derived from immobilisation is the easier separation of the... 

Photoimmobilization of IgGs was achieved by performing photoirradiation for 30 min to examine the efficiency of the immobilization process. The relative efficiencies of the photoimmobilization processes on the different azopolymers were plotted as a function of their azobenzene contents, as shown in Fig. 9.15. The immobilization efficiencies of both the CN- and H-azopolymers. increased with azobenzene content up to 30 wt% and then became saturated, although the saturated values were different between the CN- and H-azopolymers. This result indicates that an azobenzene moiety that exhibits photoisomerization is essential to immobilize IgGs on azopolymers when using a photoimmobilization process. 

Next, the authors confirmed the relationship between the immobilization of IgG and the deformation efficiency of the azopolymer. The relative immobilization efficiencies were plotted as a function of indent depth, as shown in Fig. 9.16. Incremental changes in the immobilization efficiency were observed by increasing the depth of the indents. However, the immobilization efficiency of the H-azopolymers was higher than that of the CN-azopolymers across the whole range, and this is also shown in Fig. 9.15. This difference shows that the degree of photoimmobilization is not only affected by the deformation capability but is also a property of the surface of the azopolymer and is related to the chemical structure of the azobenzene that is incorporated in the azopolymer. Whitesides and coworkers have also reported that immobilization is influenced by the properties of the surface (Ostuni et al., 2001). 

Figure 9.15. Dependence of the relative immobilization efficiency of Cy-5-labeled antibodies on azopolymer content. The solid diamonds and open circles represent CN- and H-azopolymers, respectively. CN-39 was used as the standard polymer, as shown by the solid diamond in an open diamond. Source Narita, 2007. Reprinted with permission.

Therefore, the authors attempted to examine the efficiency of the adsorption of antibodies onto the surfaces of the azopolymers. The adsorption efficiency for antibodies was determined by the efficiency of the immobilization process without photoirradiation. The value that was obtained for the CN-39 azopolymer was used as a baseline for the relative efficiency of the adsorption of antibodies. The relative adsorption efficiency of Cy-5-IgG on the azopolymers is shown in Fig. 9.17. The relative adsorption efficiency was lower than the relative photoimmobilization efficiency, which also demonstrates that photoirradiation is an important process if one wishes to firmly immobilize most of the antibodies. The relationship between the relative adsorption efficiency and the relative immobilization efficiency of Cy-5-IgG on each of the azopolymers showed that they were almost the same. Although the adsorption efficiency of the H-azopolymer was slightly higher than that of the CN-azopolymer, the difference was not sufficient to explain the differences in the immobilization efficiencies. 

From these experiments a conclusion can be drawn that the redox indicator is physically adsorbed on the surface as well as inside pores of the PETP microporous foil but the binding forces are not strong enough. The additional PVC layer should enhance the immobilization efficiency of the dye by its encapsulation. We have investigated the influence of the amount of PVC added to the bath dye solution, which governs the thickness of the covering layer. Figure 11 presents time characteristics for PETP membrane in function of PVC addition. 

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