Interaction of antitumoral 9-aminoacridine drug with DNA and dextran sulfate studied by fluorescence and surface-enhanced Raman spectroscopy

Fluorescence spectroscopy and surface-enhanced Raman spectroscopy are applied to study the interaction of the drug 9-aminoacridine (9AA) with DNA and dextran sulfate. The effect of the electrostatic interaction between the positively charged 9AA and negatively charged groups in relation to the excimer or exciplex emission is investigated. The exciplex emission of 9AA is connected to the intercalation of this drug between nucleic base residues. The importance of negative groups in this interaction is evaluated by using dextran and dextran sulfate as model polymers. The existence of negative charges seems to induce an increase of the drug concentration in the vicinity of the polymers. The role of electrostatic attraction in the 9AA dimerization is confirmed by the excimer emission of 9AA in the presence of dextran sulfate. In the case of DNA, the phosphate groups may induce the drug approach to the DNA chain, but the exciplex fluorescence emission could be due to a charge transfer between the drug and adenine-rich sequences of DNA.