Electron-mediated biosensor

Procedure-Electron-Mediated Biosensor. 1,3-DAB was electropolymerized onto the graphite from a 3 mM solution in phosphate buffer using cyclic voltammetry. The potential was cycled from 0.00 V to +0.80 V and back to 0.00 V (vs SCE) at 5 mV/s for twelve scans. l,r-dimethylferrocene (1,1 -DMF) was adsorbed onto an inverted electrode. Three successive drops of a saturated solution (10 pL each) were added to the surface and each was allowed to air dry before applying the next drop. The electrode was rinsed with water after application of each drop. 

Electron-Mediated Biosensor. Electropolymerization of 1,3-diaminobenzene (1,3-DAB), followed by adsorption of l,r-dimethylferrocene (1,1 -DMF), and immobilization of glucose oxidase, results in an easily and quickly (<2 h) constructed glucose biosensor with excellent linearity and stability (>3 months). Figure 5 shows a proposed schematic of the sensing layer consisting of film/mediator/enzyme. The ferrocene is depicted as circles... 

Willner and coworkers have extended this approach to electron relay systems where core-based materials facilitate the electron transfer from redox enzymes in the bulk solution to the electrode.56 Enzymes usually lack direct electrical communication with electrodes due to the fact that the active centers of enzymes are surrounded by a thick insulating protein shell that blocks electron transfer. Metallic NPs act as electron mediators or wires that enhance electrical communication between enzyme and electrode due to their inherent conductive properties.47 Bridging redox enzymes with electrodes by electron relay systems provides enzyme electrode hybrid systems that have bioelectronic applications, such as biosensors and biofuel cell elements.57... 

Electropolymerized Films for the Construction of Ultramicrobiosensors and Electron-Mediated Amperometric Biosensors... 

An electron-mediated glucose biosensor was made by incorporating 1, T- dimethylferrocene in electropolymerized 1,3-diaminobenzene, and immobilizing glucose oxidase. These biosensors had a linear response up to 76 mM glucose, showed little interference from oxygen, and they were stable for about three months. 

Tetrathiafulvalene containing polymeric electron transfer systems Tetrathiafulvalene (TTF) is another mediator many researchers have utilized as an electron mediator in constructing amperometric biosensors. Electrodes constructed of TTF efficiently oxidize glucose oxidase [118,119], lactate oxidase [120] and choline oxidase [121]. These sensors like those using viologen containing polymeric electron transfer systems have the... 

Aizawa has studied an enzyme (metal) electrode based on immobilized GOD, which is a redox enzyme [66]. Interfacing in this type of biosensor requires facilitation of electron transfer from the active site of the enzyme protein to the metal electrode. Various methods have been used, such as electron mediators, electron promoters, and molecular wires, to accomplish this purpose. For example, a conducting polymer, polypyrrole, formed by electropolymerization on the electrode surface, was used to form electron wires which can facilitate electron transfers to and from the metal electrode. 

The observed eledron-transfer mediating role of the ferrocenes tethered to CyDs is of importance for biosensor applications (Fig. 10.5.10). The presence of several ferrocene units on one CyD molecule may enhance the fundioning of these molecules as electron mediators. Eledroactive monolayers of CyDs to be used as surface binding sites are usually prepared by attaching a ferrocene unit far from the cavity and close to the eledrode surface [43, 71]. Compounds 1 and 2 (Fig. 10.5.10) are examples of such systems [71]. 

Kobayashi, Y. Hoshi, T. Anzai, J. Glucose and lactate biosensors prepared by a layer-by-layer deposition of eoneanavalin A and mannose-labeled enzymes electrochemical response in the presence of electron mediators. Chem. Pharm. Bull. 2001, 49, 755. 

This study describes initial electrochemical experiments, aimed at the development of an amperometric glucose biosensor using ferrocene as the electron mediator, incorporated into an oriented polypyrrole LB film. A variety of monolayer samples were prepared for cyclic voltammetry (CV) studies to determine if the ferrocene was detectable electrochemically in such a configuration. This was an important criterion,as... 

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