Electrochemistry of DNA-Modified surfaces and sensing applications

The research objective of this thesis was to develop aptamer (nucleic acid receptor) -based electrochemical sensors for molecular analytes that are of biomedical importance. Three different experimental approaches for the characterization of DNA-modified surfaces have been explored. First, cyclic voltammetric (CV) responses of redox cations, such as [Ru(NH3)6]3+, were analyzed to monitor the binding of lysozyme to aptamer-modified gold electrodes. It has been found that the decrease in the integrated charge of the electrostatically bound [Ru(NH3)6]3+ is proportional to the analyte concentration. The second part of the thesis briefly describes the application of an intercalator, 9,10-anthraquinone-2,6-disulfonic acid, as an alternative redox label for studying DNA-modified surfaces. The last part describes the synthesis and characterization of ferrocene tethered oligonucleotides (Fc-DNA). The electrochemical behavior of gold electrodes modified with Fc-DNA-strands has been evaluated.