Spectroscopic studies on the interaction of γ-cyclodextrin–daunorubicin inclusion complex with herring sperm DNA

The interaction of daunorubicin (DNR) with herring sperm DNA in cyclomaltooctaose (γ-cyclodextrin, abbrev. γ-CD) supramolecular system was studied by UV–vis absorption spectroscopy, fluorescence spectroscopy and viscosity method. On the condition of physiological pH, the results indicate that DNR prefers to form the 1:1 inclusion complex with γ-CD. These results are further supported by infrared spectrometry (IR), and X-ray diffraction (XRD). An inclusion constant (K) for the formation of γ-CD–DNR inclusion complex has been evaluated to be 9412.39 L mol−1 from the absorbance changes. It is observed that the interaction mode between γ-CD–DNR and DNA are a mixed binding, which contains partial intercalation and groove binding. The binding ratio of γ-CD–DNR with DNA is nγ-CD–DNR:nDNA = 10:1, binding constant is KΘ298.15 K = 2.44 × 105 L mol−1, enthalpy and entropy work as driven force in this action.