Abstract

A system based on electrical impedance measurements using chemically modified Silicon/Silicon dioxide electrodes with covalently bound single stranded homo-oligonucleotides was developed for DNA detection. Silanating agents (3-aminopropyltriethoxysilane, 3-glycodoxyethylpropylamine) were used to modify the electrodes and immobilize single stranded DNA. A method based on the electrochemical modification of Si substrates with bromobenzene diazonium was also used to immobilized single stranded DNA. The DNA detection system is able to recognize any electrical changes occurring at the electrode through in-phase and out-of-phase impedance measurements. Hybridization of the complementary strands causes a shift in the flat band potential due to variations in charge accumulating at the modified oxide/electrolyte interface. With these measurements, we were able to make reliable comparisons between the electrical measurements and the quantification of immobilized and hybridized single stranded DNA through radiolabeling.