Post-immobilization

Certain proteins are imstable and may deteriorate once they are on the sensor surface, even if the immobihzation procedure has worked efficiently. HIV protease, for example, dissociates into its component monomers over time and the gradual reduction in molecular weight on the sensor surface is seen as a basehne drift on the interaction profile. This makes the kinetic analysis of interactions, particularly those involving small molecules, problematic. An extra post-immobilization activation/cross-linking step with EDC/NHS may be considered in order to achieve a stable basehne. The use of cross-hnking must be empirically determined for each interaction and the process must not interfere with the activity of the protein. 

Dehydrogenases are usually multimeric enzymes. Thus, under certain conditions even thermophilic dehydrogenases may be easily inactivated by subunit dissociation, being these enzymes an excellent target for the development of stabilization strategies by immobilization and post-immobilization modification techniques as shown in Fig. 6.4.5. 

Lopez-Callego, F., Betancor, L., Hidalgo, A., Dellatnora-Ortiz, G., Mateo, C., Femandez-Lafuente, R., et al., 2007. Stabilization of different alcohol oxidases via immobilization and post immobilization technique. Enzyme Microb. Technol. 40, 278—284. 

In the field of biosensors, the benefits of diverse pre- and post-immobilization treatments on the activity and stability of enzymes are well known [23-27]. The... 

The proteolytic enzymes, trypsin, chymotrypsin, and chymoral [8076-22-0] in combination, have been used for the treatment of post-operative hand trauma, athletic injuries, and sciatica (214—216). Trypsin has also been used successfully in treating hyaline membrane disease of newborn babies, a condition usually fatal without treatment (217). Immobilized preparations of trypsin are useful in treating acute radiation cystitis following pelvic x-irradiation therapy (218). 

There is an increased risk of post-operative thromboembolic complications in women taking oral contraceptives Ifposs-bte, use of the drug is discontinued at least 4 weeks before a surgical procedure associated with thromboembolism or during prolonged immobilization. 

In this communication a study of the catalytic behavior of the immobilized Rhizomucor miehei lipase in the transesterification reaction to biodiesel production has been reported. The main drawbacks associated to the current biodiesel production by basic homogeneous catalysis could be overcome by using immobilized lipases. Immobilization by adsorption and entrapment have been used as methods to prepare the heterogeneous biocatalyst. Zeolites and related materials have been used as inorganic lipase supports. To promote the enzyme adsorption, the surface of the supports have been functionalized by synthesis procedures or by post-treatments. While, the enzyme entrapping procedure has been carried out by sol-gel method in order to obtain the biocatalyst protected by a mesoporous matrix and to reduce its leaching after several catalytic uses. 

Asymmetric catalysis provides access to several synthetically important compounds, and immobilized catalysts together with solid-supported chiral ligands have been equally instrumental. Chiral ligands immobilized on a solid support provide the advantage of being rapidly removable post-reaction while retaining their activity for further applications [139]. 

As a process analytical solution, these extrinsic reactive approaches necessitate an extrinsic optode (see later discussion), an on-line sample conditioning system or an at-Une solution such as a flow injection analysis (FIA) system or other autonomous solutions. Reaction kinetics, post analysis cleanup such as rejuvenating a substrate (optode, immobilized based immunoassays, etc.) among other complexities are additional considerations for these types real-time analysis methods. ... 

The second method of catalyst incorporation in mesoporous materials involves, generally, multi-step syntheses where organic moieties (i.e. amines, phosphines, thiols) are immobilized followed by post modification toward the final product. Alternatively, the catalyst may be synthesized as the corresponding alkoxysilane complex followed by immobilization into the mesostructured materials. For instance, Kiihn and co-workers demonstrated covalent... 

The amperometric transduction of an immunoreaction consists in the post-labeling of the detected target by an enzyme able to catalyze the production or the consumption of electroactive species. The electrochemical oxidation or reduction of the latter at a constant potential applied to the immunosensor provides thus a current, whose intensity is proportional to the amount of immobilized target. 

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