Modulation of base selectivity for a base-discriminating fluorescent nucleobase by addition of mercury ion

Highly sensitive and selective mercury sensor based on mismatched base pairing with dioxT

A highly selective and sensitive sensor for mercury was designed based on a new fluorescent nucleobase, dioxT. Its metal-sensing ability was investigated using mismatched dioxT-T and dioxT-C base pairing. The sensor exhibited a high sensitivity (quenching efficiency, 80%, 1 : 1 binding mode) and selectivity upon the addition of mercury ions.

Synthesis and Fluorescent Properties of Bi- and Tricyclic 4-N-Carbamoyldeoxycytidine Derivatives

New bi- and tricyclic deoxycytidine derivatives (dChpd, dCmpp, dCtpp, dCppp) were synthesized as analogues of a fluorescent nucleoside, dChpp, previously reported. The carbamoyl group of dChpd and the 5-position of the cytosine ring are bridged via an ethylene linker so that the modified group forms a nonplanar structure with the cytosine ring. The fluorescent study of dChpd indicated that the coplanar structure between the carbamoyl group and the cytosine ring is of importance. N-Methylation of the carbamoyl group (dCmpp) weakened the intensity of the fluorescence of dChpp, and the derivative (dCtpp), which had a thiocarbamoyl group, lost its fluorescent property. Moreover, addition of a pyrrolo-ring (dCppp) to dChpp enhanced the intensity of fluorescence, and an emission light was observed with a marked Stokes shift of 120 nm.

Fluorescent 5-Alkynyl-2′-Deoxyuridines: High Emission Efficiency of a Conjugated Perylene Nucleoside in a DNA Duplex

Four fluorescent 5-alkynyl-2'-deoxyuridines were studied in DNA oligonucleotides and their duplexes. The fluorescence response to hybridization differs dramatically for nucleosides containing a perylene fluorochrome either conjugated or not conjugated to the nucleobase. The conjugated nucleoside, 5-(perylen-3-ylethynyl)-2'-deoxyuridine, shows enhanced long-wavelength emission in the DNA duplex, in contrast to the blue fluorescence of perylene on a flexible linker (in 5-[(perylen-3-yl)methoxyprop-1-ynyl]-2'-deoxyuridine), which is quenched upon duplex formation.