Immobilization with Support Materials

Improved tolerance of cells from substrate and end-product inhibition Improved genetic stability. 

Cell immobilization techniques Cell immobilization techniques are classified into two major groups immobilization with support materials, and selfimmobilization. It is crucial to determine which technique is most suitable for a given biomanufacturing process with a specific cell line. For example, gel entrapment may not be suitable for producing primary metabolites, which is coupled with cell growth [1] self-immobilization of cells is more appropriate for the production of low-value bulk products, such as biofuels. 

On the other hand, understanding different techniques for cell immobilization may help develop new applications of a certain approach. For example, self-flocculation is commonly used to separate yeast cells from culture broth in the brewery industry, which provides a clue for developing a cost-effective harvesting technology for microalgae biomass production. 

Apart from the method itself, the selection of support materials is another crucial decision to be made in the course of preparing cell immobilization. Ideally, the support materials should meet the following criteria  

Other criteria, such as physical properties (e.g., porosity, swelling, and compression) as well as possibility for microbial growth, biodegradabUity, and solubility, are more application-specific [11]. During the past years, many different types of cell-supporting materials for immobiUzation have been developed. This include 

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Techniques of attachment, entrapment, and encapsulation are most widely used for cell immobilization with support materials, which are illustrated in Figure 7.1. These techniques can be applied to essentially all the viable or nonviable wholecell systems of potential interest microorganisms, plant cells, and mammalian and insect cells [2]. Although most of the principles associated with enzyme immobilization are directly applicable to cell immobilization, due to the complete difference in size and biochemical properties between enzymes the cells, the relative importance of these methods is considerably different [10]. 

Techniques used for cell immobilization, for example, those with support materials (surface attachment, entrapment, or encapsulation) or self-immobilized ... 

On the other hand, several oxidases are known to generate hydrogen peroxide, acting as an oxidant in the CL system, from corresponding substrates. IMERs in which the oxidases are immobilized on adequate supporting materials such as glass beads have been developed. IMERs are often used for flow injection with CL detection of uric acid and glucose, and are also applicable to the CL determination of acetylcholine, choline, polyamines, enzyme substrates, etc., after online HPLC separation. 

The principle of a three-phase membrane extraction is illustrated in Figure 1.28. An organic solvent is immobilized in the pores of a porous polymeric support consisting of a flat filter disc or a hollow fiber-shaped material. This supported liquid membrane (SLM) is formed by treating the support material with an organic solvent that diffuses into its pores. The SLM separates an aqueous... 

Immobilization of the bilayer membranes as thin solid films is required when the bilayer membranes are used as novel functional materials. Casting method is a simple way to immobilize the bilayer membrane on a solid support from an aqueous solution by drying. Polymer film is easily prepared when the cast film of polymerizable bilayer membrane is polymerized. A free standing polymer film prepared by photo polymerization of the cast film of diacetylene amphiphiles was reported by O Brien and co-workers [34]. Composition with macromolecular materials is another way of polymer film preparation. Bilayer membranes are immobilized as polymer composites by the following physical methods ... 

In this chapter we shall focus on the synthesis and adsorption characteristics of a CMS, prepared by a co-condensation or sol-gel route following the S°I° (S°, a neutral amine 1°, a neutral inorganie preeursor) pathway [3,6]. Immobilization of some cobalt(III) oxo clusters on CMS support, characterization of the resultant supported materials, and the use of these Co(III)-CMS materials in eatalytie oxidation rmder enviromnentally friendly conditions are also described. Related results available in the published literatine are also included at appropriate places with a view to broadening the scope of oin discussion. 

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