Abstract:In order to develop a robust biosensor based on quartz crystal microbalance technique for antigen detection, a control of the steps of the surface functionalization has been performed by impedance spectroscopy. The gold electrode is functionalized with the self-assembled monolayer technique. The high insulating properties of the acidic thiol monolayer has been characterized with cyclic voltammetry and impedance spectroscopy. The modified surface is activated with N-hydroxysuccinimide(NHS) and 1-(3-(dimethylamino)propyl)-3-ethylcarbodimide hydrochloride(EDC) cross-linker for antibody coupling. The non-specific sites are blocked with bovin serum albumine molecules. Different concentrations of antigen can be detected with a good reversibility in real time with the quartz crystal microbalance.

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Abstract:The development of biosensors for detection and identification of DNA sequences by hybridization may reduce assay time and allow direct quantitation of the target. This article describes the use of impedance spectroscopy technique for digoxigeninthiol-labeled ssDNA probe immobilization, anti-digoxigenin binding and targeted DNA hybridization. The analysis of the impedance spectra in terms of equivalents circuits of the gold/electrolyte interface and gold/digoxigenin-thiol-labeled/electrolyte interface is discussed. The DNA hybridization shows a variation in the impedance spectra.

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