Chemical Sensors based on Higher-Ordered Structures of Abiotic Nucleobases

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1. Template-assisted preferential formation of syn photodimer in a pyrophosphate-induced self-assembly of a thymine-functionalized isothiouronium receptor: The effect of anion-templation is investigated for the photodimerization of a thymine-functionalized isothiouronium receptor. The receptor forms a photodimer at the thymine moiety is methanol upon the UV-irradiation, while the isothiouronium moiety works as on oxoanion binding site via o two-point hydrogen-bonding motif. As compared to the case of free receptor, the presence of pyrophosphate (PPi) resulted is the preferential formation of the cis-syn type photodimer, which would be desirable to recognize the templated PPi.Fluorescence Detection of Creatinine by a Hydrogen-Bonded Guanosine Octamer: We report the design and characterization of guanosine-based octamers held together by twenty-four hydrogen bonds and stacking interaction, capable of fluorescent detection of a clinically important substrate. The octamers consist of two c … More yclic guanosine-quartets, an formed by Hoogsteen base-pairing, and also by hydrogen bonds two quartets are coupled together so as to stack with a counterclockwise rotation. When creatinine binds to guanosine of the octamer by three hydrogen bonds similar to Watson-Crick base-pairing, the octamer labelled with pyrene dissociates to give a monomeric form accompanied by the change in visible fluorescence from green to purple.Use of A basic Site Containing DNA Strands for Nucleobase Recognition in Water: Nucleobase recognition in water is successfully achieved by the use of an abasic site (AP site) as the molecular recognition field. We intentionally constructed the AP site is DNA duplex so as to orient the AP site toward a target nucleobase, and examine the complexation of 2-amino-7-methylnaphthyridine (AMND) with nucleobases at the AP site. AMND is found to selectively bind to cytosine base (K_<11>>10^6M^1) accompanied by remarkable quenching of its fluorescence, and is available for selective and visible detection of a single-base alternation related to the cytosine base. Less