Genosensors impedimetric

Figure 9.4. Schematic representation of a impedimetric genosensor [sandwich hybridization assay]. Unmodified PGR products [b] were captured at the sensor interface [a] via sandwich hybridization with the surface-tethered probe and a biotinylated signaling probe. The biotinylated hybrid [c] was then coupled with a streptavidin-alkaline phosphatase conjugate [d] and finally exposed to the substrate solution [e]. The biocatalyzed precipitation of an insulating product [f] blocked the electrical communication between the gold surface and the [Fe(CN]6] redox probe [published by Elsevier in Ref. 50].

Electrochemical genosensors for the detection of bacteria were introduced about a decade ago. Miniaturization and advanced microfabrication technology have made it compatible with bacteria DNA diagnostic. This technology is cost effective, fast, and accurate. The bioaffinity and biocatalysis reactions generate either amper-ometric, voltametric, impedimetric, or conductimetric signals on screen-printed transducer chips (SPC), which is proportional to the number of immobilized DNA copies on the SPC surface. 

Bonatmi, A., Esplandiu, M.J., del Valle, M. Impedimetric genosensors employing COOH-modified carbon nanotube screen-printed electrodes. Biosens. Bioelectron. 24(9), 2885-2891 (2009)... 

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