Analytical strategies for amperometric biosensors based on chemically modified electrodes.

Various strategies based on the use of chemically modified electrodes for the development of amperometric biosensors are described. Particular emphasis is placed on materials capable of catalyzing the oxidation of NADH and coupling these with enzymatic activities for biosensor construction. In terms of electrocatalysts, the discussion will centre on electrodeposited films of 3,4-dihydroxy benzaldehyde (3,4-DHB) and related analogs as well as on electrodeposited films of transition metal complexes of 1,10-phenanthroline-5,6-dione (phen-dione).

Characterization of the gene encoding nitrite reductase and the physiological consequences of its expression in the nondenitrifying Rhizobium "hedysari" strain HCNT1.

Rhizobium "hedysari" HCNT1 is an unclassified rhizobium which contains a nitric oxide-producing nitrite reductase but is apparently incapable of coupling the reduction of nitrite to energy conservation. The gene encoding the nitrite reductase, nirK, has been cloned and sequenced and was found to encode a protein closely related to the copper-containing family of nitrite reductases. Unlike other members of this family, nirK expression in HCNT1 is not dependent on the presence of nitrogen oxides, being dependent only on oxygen concentration.

Electrocatalytic reduction of nitric oxide at electrodes modified with electropolymerized films of [Cr(v-tpy)2]3+ and their application to cellular NO determinations.

Nitric oxide can be electrocatalytically reduced at electrodes modified with electropolymerized films of [Cr(v-tpy)2]3+. Upon further modification with a thin film of Nafion (to prevent interferences from anions, especially nitrite), these electrodes can be employed as NO sensors in solution with submicromolar detection limits and fast response. We have carried out preliminary studies of cellular NO release from Rhodobacter sphaeroides bacterial cells with excellent results.