Study on the interaction between quaternary ammonium salt of chitosan and calf thymus DNA

2-Hydroxypropyltrimethyl ammonium chloride chitosan( HTCC) were synthesed in heterogeneous system and characterized by IR and NMR spectroscopy. HTCC was the product that the N-H of CS located at C2 was replaced by quaternary ammonium salt. In the physiplogical environment( p H = 7.4). The interaction of HTCC with calf thytus DNA( ct DNA) were performed by fluorescence spectra and circular dichroism spectra,using acridine orange( AO) as a molecular probe.The analysis of UV Vis and fluorescence spectra showed that there was strong interaction between HTCC and ct DNA,the addition of HTCC made the fluorescence quenched effectively,which fitted the characteristics of the static fluorescence quenching. The circular dichroism spectra and thermal denaturation experiment proved that they combined with each other through the intercalative binding mode.