Electrode biochemical

For example, phenol oxidation [6] was implemented with the help of immobilized catalase monomer. It has been proved experimentally that catalase monomers are stable and possess high activity at pH 3.02, when usual peroxidases become inactive. This capability of hetero-genized catalase monomers may be used for the construction of biochemical electrodes for biosensors. 

Potcntiomctric Biosensors Potentiometric electrodes for the analysis of molecules of biochemical importance can be constructed in a fashion similar to that used for gas-sensing electrodes. The most common class of potentiometric biosensors are the so-called enzyme electrodes, in which an enzyme is trapped or immobilized at the surface of an ion-selective electrode. Reaction of the analyte with the enzyme produces a product whose concentration is monitored by the ion-selective electrode. Potentiometric biosensors have also been designed around other biologically active species, including antibodies, bacterial particles, tissue, and hormone receptors. 

Entrapment of biochemically reactive molecules into conductive polymer substrates is being used to develop electrochemical biosensors (212). This has proven especially useful for the incorporation of enzymes that retain their specific chemical reactivity. Electropolymerization of pyrrole in an aqueous solution containing glucose oxidase (GO) leads to a polypyrrole in which the GO enzyme is co-deposited with the polymer. These polymer-entrapped GO electrodes have been used as glucose sensors. A direct relationship is seen between the electrode response and the glucose concentration in the solution which was analyzed with a typical measurement taking between 20 to 40 s. 

By calibration against solutions containing known activities of the ion being determined, measurement of the current can be used to ascertain the activity of the ion in the test solution. Such measurements can be carried out with very small volumes of liquid, and find application in biochemical analyses.36 37 However, the simpler ion-selective electrodes discussed above can be readily adapted for dealing with small volumes, and even for intracellular measurements. 

Microelectronic circuits for communications. Controlled permeability films for drug delivery systems. Protein-specific sensors for the monitoring of biochemical processes. Catalysts for the production of fuels and chemicals. Optical coatings for window glass. Electrodes for batteries and fuel cells. Corrosion-resistant coatings for the protection of metals and ceramics. Surface active agents, or surfactants, for use in tertiary oil recovery and the production of polymers, paper, textiles, agricultural chemicals, and cement. 

Recent research development of hydrodynamics and heat and mass transfer in inverse and circulating three-phase fluidized beds for waste water treatment is summarized. The three-phase (gas-liquid-solid) fluidized bed can be utilized for catalytic and photo-catalytic gas-liquid reactions such as chemical, biochemical, biofilm and electrode reactions. For the more effective treatment of wastewater, recently, new processing modes such as the inverse and circulation fluidization have been developed and adopted to circumvent the conventional three-phase fluidized bed reactors [1-6]. 

KUMAMOTO M and soNDA T (1998) Evaluation of the antioxidative activity of tea by an oxygen electrode method , Biosci Biotechnol Biochem, 62, 175-7. 

Hagen WR. 1989. Direct electron-transfer of redox proteins at the bare glassy-carbon electrode. Eur J Biochem 182 523-530. 

Karyakin AA, Morozov SV, Karyakina EE, Zorin NA, Perelygin VV, Cosnier S. 2005. Hydrogenase electrodes for fuel cells. Biochem Soc Trans 33 73-75. 

Most suitable would be the use of a perfectly NH4+ ion-selective glass electrode however, a disadvantage of this type of enzyme electrode is the time required for the establishment of equilibrium (several minutes) moreover, the normal Nernst response of 59 mV per decade (at 25° C) is practically never reached. Nevertheless, in biochemical investigations these electrodes offer special possibilities, especially because they can also be used in the reverse way as an enzyme-sensing electrode, i.e., by testing an enzyme with a substrate layer around the bulb of the glass electrode. 

J.H. Yun, V.C. Yang, and M.E. Meyerhoff, Protamine-sensitive polymer membrane electrode characterization and bioanalytical applications. Anal. Biochem. 224, 212-220 (1995). 

L.-C. Chang, M.E. Meyerhoff, and V.C. Yang, Electrochemical assay of plasminogen activators in plasma using polyion-sensitive membrane electrode detection. Anal. Biochem. 276, 8-12 (1999). 

J.H. Thomas, S.K. Kim, P.J. Hesketh, H.B. Halsall, and W.R. Heineman, Microbead-based electrochemical immunoassay with interdigitated array electrodes. Anal. Biochem. 328,113-122 (2004). 

T. Sakata, S. Matsumoto, Y. Nakajima, and Y. Miyahara, Potential behaviour of biochemically modified gold electrode for extended-gate field-effect transistor. Jpn. J. Appl. Phys. 44, 2860-2863 (2005). 

J. Li, L.T. Xiao, G.M. Zeng, G.H. Huang, G.L. Shen, and R.Q. Yu, Amperometric immunosensor based on polypyrrole/poly(m-phenylenediamine) multilayer on glassy carbon electrode for cytokinin N6-(D2-isopentenyl) adenosine assay. Anal. Biochem. 321, 89—95 (2003). 

A. Salimi, R.G. Compton, and R. Hallaj, Glucose biosensor prepared by glucose oxidase encapsulated sol-gel and carbon-nanotube-modified basal plane pyrolytic graphite electrode. Anal. Biochem. 333, 49— 56 (2004). 

K. Wu, J. Fei, and S. Hu, Simultaneous determination of dopamine and serotonin on a glassy carbon electrode coated with a film of carbon nanotubes. Anal. Biochem. 318, 100-106 (2003). 

C. Cai and J. Chen, Direct electron transfer and bioelectrocatalysis of hemoglobin at a carbon nanotube electrode. Anal. Biochem. 325, 285-292 (2004). 

A. Salimi, A. Noorbakhsh, and M. Ghadermarz, Direct electrochemistry and electrocatalytic activity of catalase incorporated onto multiwall carbon nanotubes-modified glassy carbon electrode. Anal. Biochem. 344,16-24 (2005). 

Diffusion Currents. Half-wave Potentials. Characteristics of the DME. Quantitative Analysis. Modes of Operation Used in Polarography. The Dissolved Oxygen Electrode and Biochemical Enzyme Sensors. Amperometric Titrations. Applications of Polarography and Amperometric Titrations. 

The Dissolved Oxygen Electrode and Biochemical Enzyme Sensors... 

There is a longstanding demand for a simple and portable instrument for the detection and measurement of oxygen dissolved in water. Suitable electrodes have been developed and more recently have been ingeniously used as the basis for a range of biochemical sensors. 

Potentiometric enzyme-based electrodes have found application in clinical, pharmaceutical, food and biochemical analyses to enable the selective determination of a wide range of important enzyme substrates, including amino acids, esters, amides, acylcholines, /Mactam antibiotics, sugars, enantioselective drugs and many others [74]. 

A different and simpler approach to the measurement of P/O ratios came from the introduction of an oxygen electrode suitable for biochemical studies. Chance and Williams (1955) established conditions under which mitochondrial respiration, in the presence of excess substrate, was totally dependent on the amount of ADP available, i.e., the mitochondria were exhibiting respiratory control. From the change in potential when a known amount of ADP was admitted into the electrode vessel, the oxygen uptake and thus the P/O ratio could be determined, completely confirming the earlier results. 

By 1930 the H+ electrode, which was not suitable for biological situations when CO2/HCO3 were present, was replaced by the glass electrode (Hughes, Maclnnes, and Dole). This came into routine use in biochemical laboratories in the 1940s, giving an accuracy of 0.01 pH unit compared with 0.1 unit obtained colorimetrically. 

This measurement is actually one of pH. The principle involves the measurement of the pH of a bicarbonate solution separated from the sample by a CCh-permeable membrane. CO2 diffuses in (or out) and changes the bicarbonate solution pH in proportion to the pCCh in the sample. This method has all the drawbacks of pH measurement with a glass electrode. The problems associated with this method perhaps explain why it is not widely used in biochemical engineering laboratories and process streams despite its considerable metabolic significance 5 ... 

Y-H. Lee and G. Tsao, Dissolved oxygen electrodes, in Advances in Biochemical Engineering, Volume 13 (T. K. Ghose, A. Fieehter, and N. Blakebrough, eds.). Springer-Verlag, Berlin (1979). 

Tamura S, Sugiyama T, Minami Y, et al. 1986. Analysis of debromination of 1,2-dibromoethane by cytochrome P-450-linked hydroxylation systems as observed by bromide electrode. J Biochem 99 163-171. 

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