Kinetic studies of the interaction between DNA and polycations based on polyasparthylhydrazide

In the present paper, a systematic kinetic study on the interaction between interpolyelectrolytes such as positive-charged polymers and DNA was carried out. In particular, a qualitative–quantitative kinetic investigation on the interaction between copolymers of the α,β-poly(aspartylhydrazide) and DNA calf thymus filaments was performed. This study gives a new model starting from a well known “pseudo-phase model”, and permits to give a qualitative explanation about the trends of experimentally observed kinetic constants by varying the concentration of one of the two poly-electrolytes. Moreover, this study permits to verify the dependence of the binding constants KPAHy–CPTA and KDNA from the cationic copolymer (PAHy–CPTA) concentration and from the DNA concentration, respectively, during the formation process of polyplexes, by the kinetic analysis. It was also possible to know the kinetic constants of the complex formation by the proposed kinetic model, both in the aqueous pseudo-phase than in the non-aqueous pseudo-phase formed by the component in excess. From the parameters (a) and (b), information on the kinetic nature of the interaction between these electrolytes were obtained (cooperative and anti-cooperative bond).