Ferrocenes hydrogen peroxide

V.S. Tripathi, V.B. Kandimalla, and H.X. Ju, Amperometric biosensor for hydrogen peroxide based on ferrocene-bovine serum albumin and multiwall carbon nanotube modified ormosil composite. Biosens. Bioelectron. 21,1529-1535 (2006). 

Fig. 18b.9. Example cychc voltammograms due to (a) multi-electron transfer redox reaction two-step reduction of methyl viologen MV2++e = MV++e = MV. (b) ferrocene confined as covalently attached surface-modified electroactive species—peaks show no diffusion tail, (c) follow-up chemical reaction A and C are electroactive, C is produced from B through irreversible chemical conversion of B, and (d) electrocatalysis of hydrogen peroxide decomposition by phosphomolybdic acid adsorbed on a graphite electrode.

Ferrocene biosensors continued) hydrogen peroxide, 654 hydroperoxides, 688... 

Horseradish peroxidase catalyzes the oxidation of ferrocenes into ferricenium cations by hydrogen peroxide according the stoichiometric Eq. (37) (113). 

Turning to assays using sensors that require more than a simple cut in the sample, Bergann et al. [37] paid considerable attention to sample preparation in attempts to measure lactate in meat with a sensor (not thick film) based on reaction of hydrogen peroxide with a platinum electrode or on the reaction of ferrocene carboxylate with the active site of lactate oxidase. Sample preparation entailed extraction into buffer following grinding. In some cases, ground samples were left to allow the lactate to diffuse into the buffer solution. This was quite effective but slow (up to 90 min). Ultimately, the quality of the assay was dependent on the method of sample preparation. 

A recent successful approach uses mediators like ferrocene, which reoxidizes the FADH 2 in the glucose oxidase molecule without forming hydrogen peroxide (85). Using ferrocene results in a more stable electrode system and a larger dynamic concentration range. The ferrocene molecule is immobilized by adsorption to graphite or other carbon electrodes onto which the enzyme can be deposited. 

The flexibility of the sol-gel process allows multiple approaches to enzymatic activity monitoring. The formation of hydrogen peroxide can be followed by optical measmements using another enzymatic reaction in which the oxidation of an organic dye is catalyzed by a peroxidase (HorseRadish Peroxidase HRP), coentrapped with GOD. The presence of glucose in the solution can also be detected via electrochemical means by following the redox reactions at the active site of GOD. However, because of the steric hindrance of the protein molecule, a ferrocene mediator has to be used in order to transfer electrons from the hidden active site to the electrode. Alternatively, oxygen consumption can be measmed with a Clark electrode. The hybrid gel is deposited on a Pt cathode... 

Favorski rearrangement, 1092, 1202 Fehling solution, 390 Fenton s reagent, see Hydrogen peroxide, with salt or oxide catalysts Ferric chloride, 297, 390-392, 702, 814 anhydrous, 392 Ferrocene, 181, 392 Ferrous chloride, 392 Ferrous sulfate, 393 Fieser reagent, 145 Fieser s solution, 222, 393, 737 Filter aid, see Celite Fischer indole synthesis, 899 Fischer reagent, see Karl Fischer reagent Fisetin, 64... 

Antiochia, R. Lavagnini, I. Magno, F. Electrocatalytic oxidation of dihydronicotinamide adenine dinucleotide with ferrocene carboxylic acid by diaphorase from Clostridium kluveri. Remarks on the kinetic approaches usually adopted. Ekctroanalysis 1999, 11, 129-133. Sanchez, P. D. Ordieres, A. J. M. Garcia, A. G. Blanco, P. T. Peroxidase ferrocene modified carbon paste electrode as an amperometric sensor for the hydrogen-peroxide assay. Ekctroanalysis 1991, 3, 281—285. 

Tsai, W. G. Gass, A. E. G. Ferrocene-modified horseradish-peroxidase enzyme electrodes—a kinetic-study on reactions with hydrogen-peroxide and linoleic hydroperoxide. Analyst 1995, 120, 2249—2254. 

Vidal, J. G. Yague, M. A. Gastillo, J. R. A chronoamperometric sensor for hydrogen-peroxide based on electron-transfer between immobilized horseradish-peroxidase on a glassy-carbon electrode and a diffusing ferrocene mediator. Sensor Actuator B-Chem. 1994, 21, 135-141. 

A variety of compounds have been used as mediators in enzyme biosensors (Table 3). The most common mediators used for hydrogen peroxide and glucose detection are ferrocenes and its derivatives. 

Figure 5. Hydrogen peroxide calibration curve for three different electrode systems MP and ferrocene-immobilized polyion complex membrane (a), ferrocene-immobilized poly-ion complex membrane (b). and bare glassy electrodes (c).

Yabuki S Mizutani F, Hirata Y. Preparation of a microperoxidase and ferrocene-immobilized polyion complex membrane for the detection of hydrogen peroxide. J Electroanal Chem 1999 468 117-120. 

A similar but chiral ligand system 110 was developed by Hidai by treatment of the known ferrocene 109 with hydrogen peroxide followed by methyl-ation with Mel and subsequent treatment of the ammonium salt with sodium cyclopentadienide and reduction of the phosphane oxide with LiAlH4 (Scheme 17). 

Typically, ferrocenium/ferrocene are used as oxidised/reduced mediator couple. In the absence of the mediator, oxygen, O2, and GOx (red.) react to form hydrogen peroxide, H2O2, and GOx (ox). The mediator ferrocene can be re-oxidised at the electrode at much less extreme potentials than H2O2 and thus background current from other blood components can be minimised. 

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