Doubly thiazole orange-labeled cytidine for functional expansion of a hybridization-sensitive probe

A 2′-deoxycytidine derivative modified by two thiazole orange dyes has been designed for functional expansion of hybridization-sensitive fluorescence probes. This nucleotide was synthesized by a procedure that included protection of the cytosine amino group by di(n-butyl)formamidine formation, followed by incorporation into DNA. The fluorescence of the synthesized DNA was controlled by excitonic interaction, showing strong fluorescence upon hybridization with the target nucleic acid and effective quenching in a single-stranded state of the probe.