Glutaraldehyde, covalent bonding

AOD was successfully immobilized on aminopropyl-functionalized glass beads by covalent bonding through glutaraldehyde with an average retention efficiency of 95.14% (see Table 2). The method used for enzyme immobilization showed good reproducibility with a relative SD of 2.85%. 

The stability of covalent bonds formed in method A have been tested by washing off the immobilized enzyme with detergents.40 This study indicated that glutaraldehyde reacts quickly with the APTS surface with the formation of stable bonds. The enzymes adsorb to the activated surface, with the majority being adsorbed within the first minute. Stable covalent bonds are formed between the glutaraldehyde and the enzyme. 

The experimental conditions for the covalent bonding of fluorescent molecules and antibodies to the spheres by means of the cyanogen bromide, carbodiimide and glutaraldehyde methods. 

Forccd flow mode. Invertase, an enzyme, can be chemically immobilized to the surfaces of ceramic membrane pores by the technique of covalent bonding of silane-glutaraldehyde [Nakajima et al., 1989b]. The substrate (reactant), during the sucrose conversion process, enters the membrane reactor in a crossflow mode. Under suction from the other side of the membrane, the substrate flows into the enzyme-immobilized membrane pores where the bioconversion takes place. Both the product and the unreacted substrate indiscriminately pass through the membrane pores. Thus, no permselective properties are utilized in this case. The primary purpose of the membrane is to provide a well-engineered catalytic path for the reactant, sucrose. 

Natural polymer-based networks have also been investigated. The proteins etc comprising antibodies represent the largest group [164, 166, 169, 189] but this is of course a specialised area. Poly(saccharides), in particular starch [60], dextran [161], dextrin [161] and maltohexose [161], and also natural polypeptides, mainly enzymes [162-165], embody the more accessible biopolymers. In some instances imprinting is achieved through formation of covalent bonds, with crosslinkers like cyanuric chloride or glutaraldehyde. Likewise chitin derivatives similarly crosslinked have been exploited [136]. 

A number of methods are being tested for enzyme immobilization. The method selected depends on the operating details of the enzyme system employed and the nature of the solvent to be used, which is usually water. Enzyme, or inactivated cells, may be encapsulated in a film, or encased in a gel, which is permeable to both the substrate and product, but not to enzyme [77]. Porous glasses or insoluble polymers such as a derivatized cellulose may be used as a support onto which enzyme is adsorbed. Pendant functional groups of a polymer, such as those of the ion-exchange resins, can be used either to ionically bind the enzyme to the resin active sites or to covalently bond the enzyme to the resin [79]. The enzyme may be bonded to a polymer backbone chain using a bifunctional monomer such as glutaraldehyde to react with enzyme sites that do not affect its catalytic activity [80]. 

Immobilized Enzyme. Figure 3.100 is a schematic of a continuous immobilized enzyme membrane reactor. Here the enzyme is immobilized within the sponge wall of UF hollow fibers. The membrane skin, on the inner wall of the fiber, acts as a retentive barrier to enzyme transport into the lumen of the fiber. This means it is not necessary to immobilize the enzyme onto the membrane surface unless deactivation results. (If immobilization is desirable, glutaraldehyde may be used to crosslink the enzyme or cyanogen bromide may be used to covalently bond the enzyme in place.)... 

The final immobilisation procedure that have been used is cross-linking and involves joining the enzymes to each other forming a large, three-dimensional complex structure, achieved by physical or chemical methods. The chemical methods of cross-linking involve covalent bond formation between the protein molecules by means of a bi- multifunctional res ent such as glutaraldehyde and toluene diisocyanate. ... 

Covalent bonding of bacteria to surfaces is typically accomplished by the use of glutaraldehyde or similar cross-linking agents. It is difficult to predict the effect of bonding of bacteria onto various surfaces. However, cells of various types have been successfully bound to polyethylene, carboxymethyl cellulose, and amine glass beads. 

Gasnier et al. [138] also reported the catalytic determination of reduced nicotinamide adenine dinucleotide (NADH) at very low potentials (-0.25V), with excellent sensitivity and stability by using a G CE modified with PEI functionalized with Do and glutaraldehyde as a linker (PEI-Glu-Do). The presence of Do covalently bonded to PEI promotes hydrophobic x-interactions with the CNT walls conferring better stability and mechanical strength to the dispersion compared with nonmodified PEI. 

PTFE tube enzymes were reacted with crosslinker agents, paraformaldehyde, and glutaraldehyde to facilitate enzyme-enzyme covalent bonding on PTFE tube Trypsin, chymotrypsin, alkaline phosphatase Multidigestion of cytchrome C, and pepsin A [123]... 

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