Study on the Interaction between Morin-Bi(III) Complex and DNA with the use of Methylene Blue Dye as a Fluorophor Probe

Based on our investigation, although both morin-Bi(III) complex and morin can bind to DNA, the nature of the binding was found to be different for each of them. In the presence and absence of the DNA, the morin-Bi(III) complex shows different spectral characteristics which agree with those observed for other intercalators. In this work, the interaction of morin-Bi(III) complex with calf thymus DNA was investigated with the use of methylene blue (MB) dye as a spectral probe and application of UV-Vis spectrophotometry, fluorescence spectroscopy and cyclic voltammetry. The 2:1 morin-Bi(III) complex ratio was calculated by UV-Vis spectroscopy (mole ratio method). The fluorescence signal of Bi(III)-morin complex is increased with DNA addition whereas the fluorescence signal of Morin is decreased with DNA addition. The fluorescence signal of the DNA-complex is quenched by addition of MB which confirms the displacement of the complex with MB. Cyclic voltammetry studies confirm the intercalation reaction. The results showed that only morin-Bi(III) complex can intercalate into the double helix of the DNA. The apparent binding constant of morin-Bi(III) complex with DNA is found to be 2.8 x 10(4) L mol(-1), while morin binds in a non-intercalation mode.