Theoretical and Instrumental Studies of the Competitive Interaction Between Aromatic [alpha]-Aminobisphosphonates with DNA Using Binding Probes

Fluorescence spectroscopy, UV-visible absorption spectroscopy, circular dichroism (CD) spectroscopy, viscometry, cyclic voltammetry (CV), and differential pulse voltammetry (DPV) were applied to investigate the competitive interaction of DNA with two aromatic [alpha]-aminobisphosphonates and neutral red dye (NR, intercalator) and Hoechst (Ho, groove binder) as spectroscopic probes, in a Tris-hydrogen chloride buffer solution (pH 7.4). The principal component analysis (PCA) was applied to determine the number of chemical components presented in complexation equilibrium of DNA with the aromatic [alpha]-aminobisphosphonates (B1 and B2). The spectroscopic and voltammetric studies showed that the groove binding mode of interaction is predominant in the solution containing DNA and [alpha]-aminobisphosphonates. Furthermore, the results indicated that [alpha]-aminobisphosphonate with the lengthy N-alkyl chains had a stronger interaction. The PCA and theoretical quantum mechanical and molecular mechanic methods were also utilized to determine the structure of DNA with the two [alpha]-aminobisphosphonates (B1 and B2).