Interaction of anticancer drug methotrexate with DNA analyzed by electrochemical and spectroscopic methods

Electrochemical DNA biosensor was used to study the interaction of methotrexate (MTX) with DNA immobilized on the bare surface of glassy carbon electrode (GCE). The binding mechanism of MTX with DNA was elucidated by using constant current potentiometric technique further supported by UV-Visible and FT-IR studies. The decrease in guanine peak area was used as an analytical signal for the interaction of drug with DNA in acetate buffer solution at pH 4.2 (20% ethanol). The binding constant (K) value calculated for MTX was 3.821×10(5)M(-1). UV-Visible studies indicated hyperchromic and hypsochromic shifts in the maximum absorption bands of MTX after interaction with DNA. FT-IR investigations of MTX-DNA interaction revealed significant changes in the characteristic IR absorption bands of all the bases and phosphate groups of DNA. Furthermore, the shift of characteristics bands of C=O, N-H, C-H and O-H groups of MTX endow evidence for the interaction of MTX with DNA supporting the intercalative binding between them.