Genosensors based on electrochemical impedance spectroscopy
- Autores: Alessandra Bonanni
- Directores de la Tesis: Manuel del Valle Zafra (dir. tes.)
- Lectura: En la Universitat Autònoma de Barcelona ( España ) en 2008
- Idioma: inglés
- Tribunal Calificador de la Tesis: Jordi Bartrolí i Molins (presid.), Jean-louis Marty (secret.), Gabriele Favero (voc.)
- Materias:
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- Resumen
Due to the increasing interest for biosensors and especially genosensors in the recent years, since they make possible very quick determinations employing simple equipment, and the versatility Electrochemical Impedance Spectroscopy for the study of biosensing events at the electrode surface, the principal aim of this work was the development of an impedimetric genosensor for the detection of DNA hybridization, This was achieved for the first time in our group, by using different types of electrodes such as graphite-epoxi composites (GECs) or avidin modified composites (Av-GEBs), and screen-printed electrodes (SPEs) modified with Carboxyl functionalised Multi-Walled Carbon Nanotubes.
The work was divided into three main parts according to the different protocols used for immobilization of DNA sequences onto the electrode surface.
In the first part of the study DNA probe was immobilized onto GECs surface by physical adsorption. The detection of DNA hybridization was then performed comparing the variation of interfacial charge transfer resistance (Rct) of the redox marker ferrocyanide/ferricyanide, after each further electrode surface modification. With the aim of amplifying the obtained impedimetric signal, thus increasing the sensitivity of the technique, a further step consisting of the use of strept-AuNPs was included in the protocol. The same protocol was employed for a dual-genic detection, by immobilizing two different DNA probes onto the same GEC electrode surface and detecting their complementary targets. The classification of the obtained results was performed in this case by the use of Artificial Neural Networks. The second part of this work was based on the immobilization of biotinylated DNA sequences onto Av-GEB electrode surface, exploiting the formation of avidin-biotin complex. The same protocol was also employed for the detection of double stranded DNA sequences obtained by the polymerase chain reaction (PCR) amplification of Salmonella spp samples. In the third part of the study, amino-DNA sequences (related to GMOs) were immobilized by a covalent bond onto a SPE surface. The further detection of DNA hybridization as well as sequences with base mismatches was performed as before.
