Manganese porphyrin complexes

Although soluble enzymes can be used as excellent reagents for the analysis of inorganic and organic compounds, they face a serious challenge when attempts are made to utilize them in complex matrices, like blood or crude water. Problems center about the effect of activators, inhibitors, other substrates, pH, and temperature on the soluble enzyme. However, upon immobilization most of these effects can be eliminated or minimized. For example, an enzyme with a narrow pH range of 4–6 can be transformed upon insolubilization to a more viable reagent with a broad pH range of 4–10. Also, following immobilization the enzymes are much more stable; they can be heated to 37, 40 or 50°C, with little loss of activity; and the activity persists after several thousand analysis are performed. However, the biggest advantage, analytically speaking, of immobilization, is that the insolubilized reagent becomes a much more selective reagent. No longer do many activators and inhibitors have an effect; only the most powerful can actually attack the enzyme.

Analytical Uses of Immobilized Enzymes

Optical based sensing systems that measure luminescence, fluorescence, reflectance and absorbance, etc., are some of the areas of applications of optical immunosensors. Immunological methods rely on specific binding of an antibody (monoclonal, polyclonal or engineered) to an antigen. Detection of specific microorganisms and microbial toxins requires immobilization of specific antibodies onto a given transducer that can produce signal upon attachment of typical microbe/microbial toxins. Inherent features of immunosensors such as specificity, sensitivity, speed, ease and on-site analysis can be made use for various applications. Safety of food and environment has been a major concern of food technologists and health scientists in recent years. There exists a strong need for rapid and sensitive detection of different components of foods and beverages along with the food borne and water borne pathogens, toxins and pesticide residues with high specificity. Biosensors present attractive, efficient alternative techniques by providing quick and reliable performances. There is a very good potential for application of biosensors for monitoring food quality and safety in food and bioprocessing industries in India.

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Biosensors in food processing

Recent developments in urea biosensors

Theory and applications of ion-selective electrodes

Enzyme electrode for the substrate urea

Use of ion selective electrodes in enzymic analysis. Cation electrodes for deaminase enzyme systems

Sensitized cation selective electrode

Electrochemistry of the manganese(III)-(II) hematoporphyrin IX couple

The results of polarography and cyclic voltammetry studies of hematoporphyrin IX with eight different added ligands (other than H2O and OH−) in aqueous solvent are reported. Two nitrogenous ligand molecules were found to coordinate with both manganese (III) and manganese(II) hematoporphyrin IX. Oxygenated ligands such as acetate and pyrophosphate showed no tendency to coordinate with either manganese (III) or manganese (II) porphyrin. Porphyrin adsorption on the mercury electrode is quite evident. The adsorption mechanism appears to be complicated.

Joseph G. Montalvo

Papers

Enzyme electrode for the substrate urea

Use of ion selective electrodes in enzymic analysis. Cation electrodes for deaminase enzyme systems

Sensitized cation selective electrode

Electrochemistry of the manganese(III)-(II) hematoporphyrin IX couple

Complexes of Manganese Hematoporphyrin IX With Picoline and other Nitrogenous Bases