In the last decades the interest towards personalized therapies has fostered a big number of studies dedicated to the realization and the optimization of bio-detectors to be used as fast diagnostic tools during medical treatment [1, 2, 3, 4]. Among the proposed devices the best performances, both in terms of multiplexing and cost reduction, are expected by the detectors based on electrical readout. These sensors can be integrated with microfluidic networks in the so called Lab-on-a-Chip systems and o ffer the possibility to develop complete diagnostic kits for the use as a medical practitioner’s bench tool and, ultimately, for rapid and reliable analysis in low-resource areas and in the developing world [5, 6].
In this framework we focused on the development of an electrochemical biosensor based on capacitance readout, for the detection of biomolecules in small sample volumes. We performed electrochemical impedance spectroscopy (EIS) measurements of DNA-hybridization and protein-protein interaction in electrochemical cells with microfabricated gold electrodes. The time stability of the device was tested in
two di erent configurations: two microelectrodes in a microfluidic channel; two microelectrodes plus a reference electrode in an electrochemical cell. Our results demonstrate that the three-electrode setup is more stable, more reproducible, and suitable for real-time measurements. A thorough study of the immobilization strategy of the DNA-molecules on the gold electrodes was carried out. In the last part of the
work we performed a test study of DNA-hybridization in real time and we showed that the three-electrode configuration can measure the process in-situ.
[1] Vladimir Gubala, Leanne F Harris, Antonio J Ricco, Ming X Tan, and David E Williams. Point of care diagnostics: status and future. Analytical chemistry, 84(2):487–515, 2011.
[2] V Tsouti, C Boutopoulos, I Zergioti, and S Chatzandroulis. Capacitive microsystems for biological sensing. Biosensors and Bioelectronics, 27(1):1–11, 2011.
[3] Sandro Carrara. Nano-Bio-Technology and Sensing Chips: New Systems for Detection in Personalized Therapies and Cell Biology. Sensors, 10(1):526–543, January 2010.
[4] Shaurya Prakash, M.B. Karacor, and S. Banerjee. Surface modification in microsystems and nanosystems. Surface Science Reports, 64(7):233–254, July 2009.
[5] Paul Yager, Gonzalo J Domingo, and John Gerdes. Point-of-care diagnostics for global health. Annual review of biomedical engineering, 10:107–44, January 2008.
[6] Xiaole Mao and Tony Jun Huang. Microfluidic diagnostics for the developing world. Lab on a chip, 12(8):1412–6, April 2012.
