Glutaraldehyde coimmobilization

In view of the conductive and electrocatalytic features of carbon nanotubes (CNTs), AChE and choline oxidases (COx) have been covalently coimmobilized on multiwall carbon nanotubes (MWNTs) for the preparation of an organophosphorus pesticide (OP) biosensor [40, 41], Another OP biosensor has also been constructed by adsorption of AChE on MWNTs modified thick film [8], More recently AChE has been covalently linked with MWNTs doped glutaraldehyde cross-linked chitosan composite film [11], in which biopolymer chitosan provides biocompatible nature to the enzyme and MWNTs improve the conductive nature of chitosan. Even though these enzyme immobilization techniques have been reported in the last three decades, no method can be commonly used for all the enzymes by retaining their complete activity. 

C.H. Lei and J.Q. Deng, Hydrogen peroxide sensor based on coimmobilized methylene green and horseradish peroxidase in the same montonorillonite-modified bovine serum albumin-glutaraldehyde matrix on a glassy carbon electrode surface. Anal. Chem. 68, 3344—3349 (1996). 

PPy-Pt electrode and the electrode was dried at room temperature. Then the enzyme was cross-linked with 2.5% glutaraldehyde by Dip dry method. Further, 10 pL of HRP (0.2 mg mL ) was coimmobilized on SOD-PPy-Pt electrode. And then the HRP-SOD-PPy-Pt electrode was immersed in 0.2 mM thionine for 24 h and allowed to dry at room temperature. 

The coreticulation described above [3] is simple to perform during multienzymatic immobilization. The required enzymes are mixed with albumin, and enough glutaraldehyde is added to cross-link the various proteins. This method is also used for the coimmobilization of creatinin amidohydrolase, creatin amidinohydrolase and sarcosine oxidase, to construct a creatinin electrode, and for the coimmobilization of a-glucosidase and glucose oxidase for the determination of starch [40]. 

Ukeda H., Kamikado H., Matsumoto K. and Osajima Y. (1989) A new approach of the coimmobilization of alcohol dehydrogenase and NAD on glutaraldehyde activated Sepharose and its application to the enzymatic analysis of ethanol. Agric. Biol. Chem., S3, 25-30. 

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