Glucose oxidase, application

With regard to biosensor applications, a wide variety of electrochemically active species (ferrocene, ruthenium complexes, or carbon and metal (Pt, Pd, Au...) [185,186] were also introduced into the sol-gel matrices or adsorbed to improve the electron transfer from the biomolecules to the conductive support [187,188]. For instance, glucose oxidase has been trapped in organically modified sol-gel chitosan composite with adsorbed ferrocene to construct a low-cost biosensor exhibiting high sensitivity and good stability [189]. 

Application of transition metal hexacyanoferrates for development of biosensors was first announced by our group in 1994 [118]. The goal was to substitute platinum as the most commonly used hydrogen peroxide transducer for Prussian blue-modified electrode. The enzyme glucose oxidase was immobilized on the top of the transducer in the polymer (Nation) membrane. The resulting biosensor showed advantageous characteristics of both sensitivity and selectivity in the presence of commonly tested reductants, such as ascorbate and paracetamol. 

B. Appleton, T.D. Gibson, and J.R. Woodward, High temperature stabilisation of immobilised glucose oxidase potential applications in biosensors. Sens. Actuators, B B43, 65-69 (1997). 

Y. Tatsu, K. Yamashita, M. Yamaguchi, S. Yamamura, H. Yamammoto, and S. Yoshikawa, Entrapment of glucose oxidase in silica gel by the sol-gel method and its application to glucose sensor. Chem. Lett. 36,1615-1618 (1992). 

Y.H. Wu and S.S. Hu, Direct electrochemistry of glucose oxidase in a colloid Au-dihexadecylphos-phate composite film and its application to develop a glucose biosensor. Bioelectrochemistry. Available online 6 May (2006). 

By application of EMMA Regehr and Regnier developed several assays for enzymes that produce (galactose oxidase and glucose oxidase) or consume (catalase) hydrogen peroxide. Unlabeled enzymes were determined in the femto-mole mass range, while detection limits of less than 10,000 molecules were reported for catalase [101]. 

CL emission. The system allows a simple determination of phosphate in 3 min with a linear range of 4.8-160 pM. Owing to its sensitivity, this method could be satisfactorily applied to the analysis of maximum permissible phosphate concentrations in natural waters [42-44], Also, the maltose-phosphorylase, mutar-ose, and glucose oxidase (MP-MUT-GOD) reaction system combined with an ARP-luminol reaction system has been used in a highly sensitive CL-FIA sensor [45], In this system, MP-MUT-GOD is immobilized on A-hydroxysuccinimide beads and packed in a column. A linear range of 10 nM-30 pM and a measuring time of 3 min were provided, yielding a limit of detection of 1.0 pM as well as a satisfactory application in the analysis of river water. 

The preparation and application of SAM systems patterned by STM and their use in catalysis was demonstrated by Wittstock and Schuhmann [123]. The patterning (local desorption) of SAMs from alkane thiols on gold was performed by scanning electrochemical microscopy (SECM), followed by the assembly of an amino-deriva-tized disulfide and coupling of glucose oxidase to form a catalytically active pattern of the enzyme. The enzymatic activity could be monitored/imaged by SECM. 

Selected entries from Methods in Enzymology [vol, page(s)j Detection and quantification, 74, 608-616 effect of antigen/anti-body ratio, 74, 613, 614 applications, 74, 614-615 controls, 74, 612 data analysis, 74, 612-613 immunoglobulin G [conjugation to glucose oxidase, 74, 610 heat aggregation, 74, 609-610 heat denaturation, 74, 610 immobilization, 74, 610] precision, 74,... 

Bioelectrocatalysis involves the coupling of redox enzymes with electrochemical reactions [44]. Thus, oxidizing enzymes can be incorporated into redox systems applied in bioreactors, biosensors and biofuel cells. While biosensors and enzyme electrodes are not synthetic systems, they are, essentially, biocatalytic in nature (Scheme 3.5) and are therefore worthy of mention here. Oxidases are frequently used as the biological agent in biosensors, in combinations designed to detect specific target molecules. Enzyme electrodes are possibly one of the more common applications of oxidase biocatalysts. Enzymes such as glucose oxidase or cholesterol oxidase can be combined with a peroxidase such as horseradish peroxidase. 

The present volume is a non-thematic issue and includes seven contributions. The first chapter byAndreja Bakac presents a detailed account of the activation of dioxygen by transition metal complexes and the important role of atom transfer and free radical chemistry in aqueous solution. The second contribution comes from Jose Olabe, an expert in the field of pentacyanoferrate complexes, in which he describes the redox reactivity of coordinated ligands in such complexes. The third chapter deals with the activation of carbon dioxide and carbonato complexes as models for carbonic anhydrase, and comes from Anadi Dash and collaborators. This is followed by a contribution from Sasha Ryabov on the transition metal chemistry of glucose oxidase, horseradish peroxidase and related enzymes. In chapter five Alexandra Masarwa and Dan Meyerstein present a detailed report on the properties of transition metal complexes containing metal-carbon bonds in aqueous solution. Ivana Ivanovic and Katarina Andjelkovic describe the importance of hepta-coordination in complexes of 3d transition metals in the subsequent contribution. The final chapter by Sally Brooker and co-workers is devoted to the application of lanthanide complexes as luminescent biolabels, an exciting new area of development. 

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