Oxidation, glucose, immobilized

Internal diffusional resistance is widely appreciated now, and tests for freedom from such Internal disguises are commonly used in kinetic studies. The level of complexity of diffusional intrusions is illustrated with consideration of an immobilized dual system glucose oxidase (E ) and catalase (E.) are used to oxidize glucose (G) to oxidized glucose (G ), and to de... 

Glucose oxidase immobilized in the porous surface of the platndzed microelectrode oxidizes glucose in a droplet sample, and the generated hydrogen peroxide is electrochemically oxidized to give anodic sensor ggniil... 

Subsequently, Au(lll) porphyrin, immobilized on MWCNT matrix, was reported by the same research group to oxidize glucose at low overpotential [208]. 

Enzyme sensors are based primarily on the immobilization of an enzyme onto an electrode, either a metallic electrode used in amperometry (e.g., detection of the enzyme-catalyzed oxidation of glucose) or an ISE employed in potentiometry (e.g., detection of the enzyme-catalyzed liberation of hydronium or ammonium ions). The first potentiometric enzyme electrode, which appeared in 1969 due to Guilbault and Montalvo [140], was a probe for urea with immobilized urease on a glass electrode. Hill and co-workers [141] described in 1986 the second-generation biosensor using ferrocene as a mediator. This device was later marketed as the glucose pen . The development of enzyme-based sensors for the detection of glucose in blood represents a major area of biosensor research. 

Figure 12.6 The immobilized glucose oxidase/lactoperoxidase system radioiodinates proteins through the intermediate formation of hydrogen peroxide from the oxidation of glucose. H2O2 then reacts with iodide anions to form reactive iodine (I2). This efficiently drives the formation of the highly reactive H2OI+ species that is capable of iodinating tyrosine or histidine residues (see Figure 12.2).

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. 

---