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

Electrochemical DNA biosensor was used to study the interaction of methotrexate (MIX) with DNA immobilized on the bare surface of glassy carbon electrode (GCE). The binding mechanism of MIX 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 MIX was 3.821 x 10(5) M-1. UV-Visible studies indicated hyperchromic and hypsochromic shifts in the maximum absorption bands of MIX after interaction with DNA. FT-IR investigations of MIX-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 MIX endow evidence for the interaction of MIX with DNA supporting the intercalative binding between them. (C) 2012 Elsevier B.V. All rights reserved.