Study on the interaction between rivanol and DNA and its application to DNA assay

Rivanol (RVN) binds to the double helical DNA with a high affinity, as deduced from the absorption and fluorescence spectral data. Extensive hypochromism and red shifts in the absorption spectra were observed when RVN binds to calf thymus DNA (CT DNA), which suggested the intercalation mechanism of RVN into DNA bases. Upon binding to DNA, the fluorescence from RVN was efficiently quenched by the DNA bases, with no shifts in the emission maximum. The large increases in the polarization upon binding to CT DNA supported the intercalation of RVN into the helix. Iodide quenching studies showed that the magnitude of K_sv of the free RVN was higher than that of the bound RVN. The results of competitive binding studies showed that RVN can be displaced by ethidium bromide. Thermal denaturation experiments exhibited that the quenching of the fluorescence from RVN by single strand (ssDNA) was smaller than that by double strand (dsDNA). The results of all above further studies also proved the intercalation of RVN into DNA base stack. Quenching of fluorescence from RVN by DNA can be employed for sensitive detection of DNA. The limit of detection for CT DNA was 16 ng ml^-1.