Glucose-sensing electrodes modified enzymes

Amperometric Glucose-Sensing Electrodes with the Use of Modified Enzymes... 

Glucose-Sensing Electrode based on PEG-Modified Enzyme... 

Amperometric glucose-sensing electrodes with modified enzymes enzyme electrode systems, 42-43 experimental description, 41 2 flow injection measurement of glucose for lipid-modified enzyme electrode, 44,45/,46f... 

In this article, we describe the preparation and use of amperometric electrodes for sensing the analytically significant substrate glucose based on a PEG-modified glucose oxidase (GOD) (4,5) and on a lipid-modified GOD (6). The PEG-modified GOD has been incorporated into a carbon paste (CP) electrode the modified enzyme exhibits higher activity in a hydrophobic CP matrix than hydrophilic, native GOD (7-10). The lipid-modified GOD has been immobilized on a glassy carbon (GC) electrode with a thin Nafion overcoat. The water-insoluble modified enzyme is far more stable between the electrode surface and the polymer layer than native GOD (77). 

Conducting polymers have been used to modify the surface properties of metallic electrodes, in particular microelectrodes [49]. TTie prosthetic functional groups covalently attached to the polymer chains can be used as molecular sensors or molecular transducers that can reversibly transfer electrochemical information between the medium and the electrodes. These systems are useful for solution sensing in both amperometric and resistometric modes. Enzymes (for example, glucose oxidase) can be incorporated directly into the polymeric layer during polymerization and subsequently used as biosensors. 

In addition to the previously described dehydrogenase-based CNT electrodes, electrochemical biosensors that employ other types of enzyme-modified CNTs have also been reported. Kowalewska and Kulesza applied CNTs with adsorbed redox mediator tetrathiafulvalene (TTF) for electrochemical detection of glucose." TTF-modified CNTs were found to facilitate electron transfer between GOx and the electrode surface for glucose detection. Jia et al. reported a similar strategy for the detection of lactate using MWCNTs modified with TTF and lactate oxidase. Since TTF does not cause skin irritation and the CNT/TTF platform also enables low-potential sensing of lactate, CNT/ TTF/lactate oxidase-based electrochemical biosensors conld be used to detect lactate in perspiration directly on human skin. This was accomplished by preparing temporary tattoos from CNT/ TTF/lactate oxidase-conductive carbon ink that was transferred onto a human subject s skin. ... 

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