A new amperometric DNA sensor was constructed using a pyrroquinoline quinone glucose dehydrogenase ((PQQ)GDH) conjugated with avidin. Our aim was to specifically detect the DNA sequence of the invA virulence gene from the pathogenic bacterium Salmonella. Probe DNA with a sequence complementary to that of a specific fragment of the invA gene was immobilized onto a carbon paste electrode. After hybridization with biotinylated target DNA, (PQQ)GDH-avidin conjugate was added and the resulting electric current was measured. The electric current is generated from glucose oxidization catalyzed by (PQQ)GDH via 1-methoxyphenazine methosulphate (m-PMS) electron mediator. The sensor response increased with the addition of glucose and in the presence of 6.3 mM glucose the response increased with increasing DNA in the range 5.0×10-8-1.0×10-5M. © 2002 Elsevier Science B.V. All rights reserved.
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