EFFECT OF MISMATCH POSITIONS ON ELECTROCHEMICAL DETECTION OF SINGLE-NUCLEOTIDE MISMATCHES

In this thesis, I systematically explore the electrochemical behavior of surface-bound 25- mer DNA duplexes that have single-base mismatches at 25 different positions. Each mismatch is located in the target strand. Target and capture strands are hybridized before attachment of the ds-DNA on gold surfaces through Au-S bonding. Electrochemical impedance spectroscopy (EIS) and scanning electrochemical microscopy (SECM) were used to evaluate if it is possible to distinguish mismatches in all 25 positions of the target strand by monitoring the electrochemical response in the presence of anionic redox markers. Our studies clearly show that it is possible to distinguish the electrochemical responses from all 25 mismatch positions using a combined EIS/SECM approach. To our knowledge this is the first systematic study exploring the electrochemical behavior of ds- DNA carrying single-nucleotide mismatches in which the position of the mismatch was varied through all possible positions on the target strand