Surface Electrochemistry of DNA Conformational Switches

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The main goal of the proposed research is to obtain a thorough knowledge of the surface electrochemistry of functional deoxyribonucleic acids (DNA). It is essential to understand the nature of DNA which plays a pivotal role in biology as the carrier of genetic information. Besides typical single strands and double helices, complex DNA nanostructures (so-called DNA conformational switches) can be constructed to have desired functions or reactivities. Using standard biochemical assays, perfect double helices and properly designed DNA switches in solution have been found to efficiently mediate charge flow. However, this is not the consensus mechanism when they are bound to an electrode surface; in that case both DNA-mediated and direct electron transfer are supported by experimental observations. The proposed research will help us to understand structure-conduction correlations in DNA and DNA nanostructures. It also has direct impact on applications: elucidation of the exact charge transport pathway in surface-bound DNA switches is crucial for the development of sensitive electronic biosensors (e.g., for monitoring disease biomarkers in blood). We will initially focus on design and labeling strategies for electrode-bound DNA switches. Combined structural and electrochemical studies will be carried out to discriminate between alternative conduction pathways in these DNA nanostructures and to quantitatively evaluate the electron transfer kinetics. The next phase of this research will comprise a comprehensive study of the signal-switching (charge conduction) mechanism and its structural basis, including real-time spectroscopic and microscopic measurements as well as solid-state experiments.