Square wave voltammetric study of interaction between 9-acridinyl amino acid derivatives and DNA

Electrochemical oxidation of newly synthesized acridine derivatives (ADs): PG, PA, EG and EA was studied using square wave voltammetry at a glassy carbon electrode. Oxidation occurs as an irreversible process for all ADs. The ADs interaction with DNA was investigated using multi-layer DNA electrochemical biosensor. The shift of dA peak in positive direction indicated that the type of interaction is most likely an intercalation. PG showed the widest range of concentration capable to interact with DNA (1 × 10^-7 M - 2.5 × 10^-4 M). Analysing logI_complexI_DNA-I_complexvslogc_AD plots, the binding constants were determined. For the lowest PG concentrations, obtained K value close to 10⁶ M^-1 refers to strong binding. The values of K for PA may be classified as medium strength, while EG and EA showed low K values. Our results unequivocally showed that the characteristics of association complexes may vary depending on the concentration of the interacting substance. The negative ΔG value for all ADs, (- 21 to - 34 kJ mol^-1), confirms the process spontaneity. The best result, indicating the most stable formed complex with DNA adsorbed at the electrode surface, showed PG when present in low concentration, order of 10^-7 M. The intercalation of ADs into DNA was supported by molecular docking analysis.