Single molecule conductance of biological building blocks purines and imidazole
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In the last decade, biological molecules such as Deoxyribonucleic acid (DNA) and some proteins have attracted attention as material candidates for molecular electronics applications. Yet, despite numerous studies of electron transport in DNA in particular, inconsistencies in experimental results persist. As a result, both the degree and mechanism of charge transport in these biological molecules remain disputed. To understand if different binding configurations of DNA on metal electrodes through unexpected moieties could be responsible for experimental inconsistencies in the literature, we investigate whether small molecules ubiquitous in both nucleic acids and amino acids, such as purines and imidazole, bind to gold electrodes and produce conductance signature. In this study, we use the Scanning Probe Microscope-based Break Junctions approach method to study single molecule conductance and binding geometry of the purine bases of DNA, particularly adenine and guanine. In addition, the Conductive Atomic Force Microscope-based Break Junction (CAFMBJ) platform has been created to simultaneously measure both electrical and mechanical properties of these single molecule junctions. Our measurements indicate that purines bind in the junction and display several robust conductance signatures on gold. We find that both purine and adenine bind through the imidazole, which is identified, for the first time, as a new linker group for single molecule conductance measurements.