Study on the Interaction of Formononetin and Herring Sperm DNA by Electrochemical Methods and Spectroscopy

The interaction of formononetin (FN) with herring sperm DNA has been studied by electrochemical methods, UV-Vis spectroscopy and fluorescence. On a poly L-cysteine film modified electrode (PLC/GCE), FN showed a couple of well-defined voltammetric peaks in 0.1 M acetate buffer of pH 5.3. As adding the herring sperm DNA into above solution, the peak current of FN decreased and no new peaks appeared. Based on the electrochemical results, the binding constant and binding ratio between FN and herring sperm DNA were determined to be 1.98×10 4 M -3 and 1:3, respectively. The UV-Vis spectroscopy indicated that the maximum absorption of FN had obviously hyperchromic effect and red shift after the interaction of DNA and FN. The interaction of DNA and FN can also make the fluorescence intensity of FN enhancement. The electrochemical and spectroscopic results indicated that the interaction of FN to DNA was an intercalative mode.