Enzymes, biosensors

Twenty years ago. Professor Saverio Mannino and Professor Joseph Wang, published a review article entitled Electrochemical Methods for Food and Drink Analysis. In this 

Nanostructured enzyme electrochemical biosensors were also recently prepared for the determination of polyphenols, the most abundant antioxidants present in diet. One configuration involved immobilization of laccase onto nickel nanoparticles (NiNPs) decorated-carboxylated multiwalled carbon nanotubes (cMWCNTs)/PANI and was applied to the 

Aleurone layer Seed coat Seed vessel 

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Gautier S.M., Blum L.J., Coulet P.R., Fiber-optic sensor with Co-immobilized bacterial bioluminescence enzymes, Biosensors 1989 4 181. 

P. Mulchandani, W. Chen, and A. Mulchandani, Flow injection amperometric enzyme biosensor for direct determination of organophosphate nerve agents. Environ. Sci. Technol. 35, 2562-2565 (2001). 

The fouling and microbial contamination of the surface during operation are main problems in the long-term use of enzyme biosensors. Wang et al. [121] reported for the first time a screen-printed electrode modified with GOD/HRP that was stable up... 

The first enzyme biosensor was a glucose sensor reported by Clark in 1962 [194], This biosensor measured the product of glucose oxidation by GOD using an electrode which was a remarkable achievement even though the enzyme was not immobilized on the electrode. Updark and Hicks have developed an improved enzyme sensor using enzyme immobilization [194], The sensor combined the membrane-immobilized GOD with an oxygen electrode, and oxygen measurements were carried out before and after the enzyme reaction. Their report showed the importance of biomaterial immobilization to enhance the stability of a biosensor. 

A.L. Crumbliss, J.Z. Stonehuerner, R.W. Henkens, J. Zhao, and J.P. O Daly, A carrageenan hydrogel stabilized colloidal gold multi-enzyme biosensor electrode utilizing immobilized horseradish peroxidase and cholesterol oxidase/cholesterol esterase to detect cholesterol in serum and whole blood. Biosens. Bioelectron. 8, 331-337 (1993). 

Immobilized catalases, for textile bleaching effluent treatment, 4 68—69 Immobilized cells, 3 670 Immobilized enzyme biosensors,... 

Imine peroxide, analytical aspects, 744 Imines, dioxirane oxidation, 1153 Immohihzed enzymes, biosensors, 687-8 Immunoassays... 

Many different types of techniques for protein immobilization have been developed using, in most cases, enzyme sensors. Early studies of enzyme biosensors often employed thick polymer membranes (thickness 0.01-1 mm) in which enzymes are physically entrapped or chemically anchored. The electrode surface was covered with the enzyme-immobilized polymer membranes to prepare electrochemical enzyme sensors. Although these biosensors functioned appropriately to... 

Analytes are also used to specify the application. Glucose enzyme sensor is an enzyme biosensor measuring the glucose. Characteristics and commercial varieties of enzyme electrodes, especially using glucose oxidase, have been extensively reviewed by Kuan and Guilbault (17). 

Utilization of whole cells and tissues in biosensor has increasingly been used. Enzyme stability, availability of different enzymes and reaction systems, and characteristics of cell surface are the advantages of using cells and tissues in biosensor designs. Multi-step enzyme reactions in cells also provide mechanisms to amplify the reactions that result in an increase in the detectability of the analytes. The presence of cofactors such as NAD, NADP, and metals in the cells allows the cofactor-dependent reactions to occur in the absence of reagents. (34, 50, 69). However, the diffusion of analytes through cell wall or membrane imposes constraint to this type of biosensors and results in a longer response time compared to the enzyme biosensors. 

Fig. 3.2 General scheme of thermistor-based enzyme biosensor...

The enzyme is immobilized on a nylon mesh, which also acts as a diffuse reflector for the light. The dynamic range of this sensor is between 1(T5 and 10 3M. Although the primary process that determines the steady-state concentration of the p-nitrophenoxide ion is the diffusion-reaction mechanism (which is governed by concentrations of all participating species), the detection of its concentration is again subject to the limitations of optical sensing of ionic species (Section 9.4.1). There are many similar optical enzyme biosensor schemes that utilize detection of... 

Application of electrochemical enzyme biosensors for food quality control... 

C. Martelet, N. Jaffrezic-Renault, Enzyme biosensor for tomatine detection in tomatoes, Anal. Lett., 37 (2004) 1611-1624. 

Z. Guang-Ming, T. Lin, S. Guo-Li, H. Guo-He and N. Cheng-Gang, Determination of trace chromium (VI) by an inhibition-based enzyme biosensor incorporating an electro polymerized aniline membrane and... 

Our research group is working on the development of electrochemical biosensors for the detection of microcystin and anatoxin-a(s), based on the inhibition of protein phosphatase and acetylcholinesterase, respectively. These enzyme biosensors represent useful bioanalytical tools, suitable to be used as screening techniques for the preliminary yes/no detection of the toxicity of a sample. Additionally, due to the versatility of the electrochemical approach, the strategy can be applied to the detection of other cyanobacterial toxins. 

Finally, it is necessary to underline the versatility of the approach. By selecting the appropriate enzyme, biosensors for other toxins can be developed. In this direction, our group has started the development of an enzyme sensor for okadaic acid, a marine toxin produced by toxigenic dinoflagellates and implicated in the diarrheic shellfish poisoning (DSP). 

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