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DNA sensing has become a very powerful tool for diagnosis, detection of the toxicmicroorganisms in food or the environment and fundamental research in molecular biology. Manytypes of DNA sensing systems have been developed, such as DNA microarrays based onfluorescence detection of hybridization using probe DNA labeled with fluorescent compound 1.While many DNA hybridization assays are suitable for diagnostic laboratories, faster, lower cost,easier-to- use, and more sensitive approaches are highly desired, especially in the case ofdecentralized screening of in- fectious diseases, electrochemical DNA sensing system would be avery promising tool since it only requires an electrode and an electrochemical analysis system,r e su lting in a simple detection system. Here are numerous labeled electrochemical DNA biosensors where the tag can be an enzyme,ferrocene, an interactive electroactive substance (a groove binder, such as Hoechst 33258, or anintercalator), or nanoparticles, Other label-free electrochemical DNA biosensors can be used. Oneof the important DNA electrochemical sensors is that the nucleic acids directly immobilized onan electrode surface for hybridization offer innovative routes 2,3. The hybridization event iscommonly detected by labeling the target DNA sequence or the reporter DNA probe with a redoxactiveenzyme. The main problem associated with the electrochemical DNA sensors mentioned so far is theirhigh-cost compared to the traditional spectrophotometric measurements in microtiter plates.Consequently, there is a growing need for developing inexpensive miniaturized sensing devicesfor electrochemical nucleic acid analysis Both photolithography and screen-printing technology,adapted from the microelectronics industry, represent attractive approaches, since they allow massproduction of low-cost electrochemical sensors like ?TAS (micro total analysis system) or DNAmicroarrays. In this paper, disposable screen-printed carbon electrodes (SPEs) were investigated as a lowcostDNA sensor on which the target DNA could be adsorbed and hybridized with a biotinylatedDNA probe. The hybridization assay was applied for the determination of amplified humancytomegalovirus DNA sequences (HCMV DNA), and the analytical performance of theelectrochemical DNA sensor was discussed and com- pared to the classical spectrophotometricmeasurements in microtiter plates. Also creation create an amperometric DNA sensor employing(PQQ)GDH for the labeling of the hybridization product. Since DNA can be easily labeled withbiotin, we chose to detect DNA hybridization via biotin /avidin binding. An oligonucleotide wasthen immobilized on a carbon paste electrode and its hybridization with the biotinylated targetoligonucleotide was detected. We chose a carbon paste electrode since we aimed at developingone-time-use sensor. The dependence of the sensor response to glucose and DNA concentrationswas investigated as well as the selectivity of the DNA detection.

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