Photoelectrochemistry of Ru(bpy)2bdppz2+??-DNA-Gold Conjugate Bryan Hunter and Samuel Phang
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The photoactive complex: Ru(bpy)2(bdppz)<sup>2+</sup> (bis(2,2?-bipyridine)-ruthenium(II)-benzo[i]dipyrido[3,2-a:2?,3?-c]phenazine) was synthesized and purified as a DNA-intercalater in order to photosensitize electron-transfer reactions on a DNA-modified metal surface. Such a device can potentially harness light energy to catalyze the production of hydrogen molecules from water as an alternative energy source. As the ruthenium complex has limited solubility in the conditions of typical DNA-mediated electrochemical experiments, complexes were prepared with varied counter-anions to attain optimal solubility. The ruthenium complex binds reversibly to double-stranded oligonucleotides, which are assembled onto a gold electrode surface by a thiol linker. Photocurrents are produced when the complex is excited and the electrons are transferred to the electrode surface through the conductive double-stranded DNA. Binding kinetics of the ruthenium complex to the DNA was determined by electrochemical assays such as linear-sweep voltammetry at a rotating-gold-disk electrode and titration experiments to produce a Langmuir fit.