Detection of abasic DNA by means of impedance spectroscopy

Abasic sites can occur in DNA for different reasons, and thus the detection of this special molecular structure has turned into the focus of research. Here we have investigated the hybridization of abasic ssDNA to immobilized ssDNA probes by impedance spectroscopy. For this purpose three different abasic 25mer ssDNA (abasic site near the electrode; in the middle and near the solution) are studied in comparison to fully complementary 25mer ssDNA. For all abasic strands the surface binding can be followed concentration dependent via impedance spectroscopy; however, the concentration range and the maximum impedance change are found to be different compared to fullmatch ssDNA. Here, the position of the abasic site within the DNA strand significantly determines the signal behavior, and thus, even allows a partial discrimination between the different abasic DNA strands. By investigating the binding in parallel by SPR, only slightly smaller surface concentrations are detected for the abasic strands in comparison to the fullmatch strand. This points to the formation of different DNA structures when abasic sites are contained.