Fluorescence quenching by methylcytosine-metal complexation.

We report the control of fluorescence emission from the fluorophore fixed on DNA using the methylcytosine-selective addition of an osmium(VI)-bipyridine complex. We synthesized the DNA modified by a microenvironment-sensitive fluorophore, 2-dimethylamino-6-acylnaphthalene. The fluorescence from the fluorophore tethered to a probe DNA was effectively quenched by the addition of the osmium(VIII)-bipyridine to the methylcytosine which is located at the immediate neighborhood of the fluorophore. The discrimination of cytosine methylation status at the mutation hot spot in p53 gene was also executed using a well-designed fluorescent DNA probe.