Impedimetric genosensors for the detection of DNA hybridization

Abstract

Impedance spectroscopy is proposed as the transduction principle for detecting the hybridization of DNA complementary strands. In our experiments, different DNA oligonucleotides were used as model gene substances. The gene probe is first immobilized on a graphite-epoxy composite working electrode based genosensor. Detection principle is based on changes of impedance spectra of a redox marker, the ferro/ferricyanide couple, after hybridization with target DNA. Resistance offered to the electrochemical reaction serves as the working signal, allowing for an unlabelled gene assay.

Label-free detection of DNA molecules on the dendron based self-assembled monolayer by electrochemical impedance spectroscopy

“…First, the impedance data shown by the Nyquist plots display sig- nificantly depressed semicircles indicating that the electron transfer takes place via more than one RC time constant (in fact RQ time constants: vide infra). The depressed semicircles are usually obtained due to highly porous electrode/electrolyte interfaces as well, in which case the mass transport of counter ions is significantly affected by the pore structures [22]. This effect is usually taken care of by introducing a constant phase element (CPE) in place of a double layer capacitor.…”

Dual‐Genic Hybridization Sensor Employing Electrochemical Impedance Spectroscopy

“…4). The origin of its use, as already explained in previous work [24], is the need to normalize the response of different genosensor units, to test the reproducibility of the results. D s /D p value should be > 1 for the hybridization experiments and % 1 for negative controls (that means D s ¼ D p , i.e., no variation of R ct value after hybridization).…”

“…Recent works are reported in the literature on the application of EIS to genosensing [19] basically based on DNA hybridization detection. Different protocols have been employed, some of them are based on the direct measurement of capacitance [20 -22] whilst others employ a redox marker to detect the hybridization signal [23,24]; others employ nanoparticles as a way to increase the sensitivity of the method [23,25,26]; enzyme schemes have been also used in some cases [27]. In this work, a dual-genic detection of DNA hybridization by impedance spectroscopy is proposed for the first time.…”

Aptamer-antibody sandwich assay for cytochrome c employing an MWCNT platform and electrochemical impedance

“…The most important parameter in this work is the electron transfer resistance (Rct), which reflects the resistance to charge transfer between the redox probe and the electrode surface. In order to compare the results obtained from the different electrodes used, and to obtain independent and reproducible results, a relative transformation of signals was needed [34]. Thus, the Δ ratio value was defined according to the following equations:…”