Spectra, Stability and Labeling of a Novel Carbazole Derivative as a Fluorescent Turn-on DNA Probe.

A novel fluorescent dye, 1-(6-carboxyhexyl)-4-(2-(9-ethyl-carbazole-3-yl) vinyl) quinolizinium bromide, was synthesized, and its structure was characterized by (1)H NMR, (13)C-NMR, IR and HRMS. The spectra properties of this dye in different solvents and under different pH value were invest'igated preliminarily, and the results showed that its fluorescent properties was affected by the polarity and the dipole moment of the solvent. The photostability and thermostability test results showed that its photoreduction rate constant was 1.64 × 10(-5) mol/Min and its fluorescent intensity decreased little after heating at 80 °C for 6 h, suggesting the dye was quite stable. In the labeling experiment of BSA and DNA with the dye, the fluorescent all intensity increased with the addition of BSA and DNA. Specially, the dye showed an excellent turn-on effect upon binding with ctDNA.