The detection of DNA hybridization has been possible with electro active molecules that monitor the electron transfer mechanism during the hybridization process which present a potential application for the creation of biosensors. It has been shown that the sensor performance (e.g., sensitivity, selectivity and stability) is highly dependent on properties of immobilized DNA probes, such as orientation, conformation and surface density. DNA hybridization has been monitored using different techniques. However, genetic testing requires the development of easy, fast and inexpensive devices to report the hybridization event. In our research we proposed to establish a bio-lab-on-a-chip technology using Radio Frequency Identification (RFID) based wireless sensing platform for the capacitive label-free detection of DNA hybridization processes. Currently, the technique that shows the most potential to report the hybridization of probe target DNA under conditions where the end product is not affected by the force to meet with the reporter requirements is electrochemical impedance spectroscopy (EIS). Previous studies involved using commercial Interdigitated Microarray (IDAM) electrodes. However, these electrodes were disposable and expensive. In order to obtain a reusable, low cost sensor, IDAM custom made electrodes were created and tested. Silver electro deposition was used in order to apply a Ag+/AgCl reference. Self-Assembly Monolayer technique (SAM) was utilized to modify the gold metal surface of IDAM electrodes with two types of modification schemes. In first scheme, the IDAM electrodes were modified with a strand of 20 bases pair sequence of Poly G terminated with an �SH group [GGG-GGG-GGG-GGG-GGG-GGG-GGSH] probe. In the second scheme, we functionalized the gold surface with carboxyl thiol and, by exploiting its -COOH group, 3'-NH2 modified DNA will be conveniently attached. After the modification, SAM modified surface studies for detection of complementary (Poly C [CCC-CCC-CCC-CCC-CCC-CCC-CCSH]]) and non-complementary (Poly T [TTT-TTT-TTT-TTT-TTT-TTT-TTSH]) sequences were carried out and EIS was used in capacitive measurements.

Electrochemical capacitive label-free detection of DNA modification and hybridization processes using custom made interdigitated gold micro electrodes

247th National Meeting (2014)

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