Effect of N-substituent in 4-styrylpyridinium dyes on their binding to DNA

Fluorescence turn-on probes for intracellular DNA/RNA distribution based on asymmetric bis(styryl) dyes

Two bis(styryl) dyes, varying in type of spacer between two mono(styryl) units, were tested for interactions with ct-DNA or cl-RNA. Both compounds showed strong affinity toward ds-DNA/ss-RNA, the binding mode of the interaction is shifting between DNA groove binding to RNA intercalation. Consequently, interaction with DNA shows a stronger flare-up of fluorescence (151 times for dye 1 and 118 times for dye 2) than when binding with RNA (23 times and 36 times correspondingly). The presence of energy transfer in the bis(styryl) system increases the Stokes shift of the dye, so when irradiating the system in the region of 370-380 nm, fluorescence is detected at 610-620 nm. The biological experiments showed that the efficient intracellular fluorescence quench was observed in the DNase digest test suggested that dyes can be applied by recognition of DNA in the presence of RNA molecules.

Styryl Hemicyanine Dye (E)-3-Methyl-2-(4-thiomorpholinostyryl)benzo[d]thiazol-3-ium Iodide for Nucleic Acids and Cell Nucleoli Visualization

(E)-3-Methyl-2-(4-thiomorpholinostyryl)benzo[d]thiazol-3-ium iodide 1 was prepared by a convenient and reliable reaction procedure. The slight molar excess of the starting benzaldehyde and the mixture of ethanol: ethyl acetate in the ratio 3:1 as a solvent afforded a pure reaction product. The photophysical properties of the dye in a TE buffer in the absence and presence of double-stranded DNA (dsDNA) were elucidated. The low intrinsic fluorescence of 1 in TE buffer is followed by an increase in the fluorescence after dsDNA binding. The dye is nontoxic for stem cells from apical papilla and the most concentrated fluorescence is detected in the cell nucleoli.