The influence of charge density of chitosan in the compaction of the polyanions DNA and xanthan.

In this study the relative importance of valence and charge density of the polycation chitosan on the compaction process of DNA and xanthan is investigated. Chitosans with approximately equal valence but differing in their charge density were employed to form polyelectrolyte complexes with the two polyanions. The resulting structures (toroids, rods, and globules) have been visualized by AFM. For DNA-chitosan the complexation process was additionally studied by utilizing the fluorescent probe ethidium bromide. The results show that not only the total charge per chitosan molecule (valence), but also the charge density is important in determining the association with polyanions such as DNA and xanthan. Furthermore, it is demonstrated that the pH at which the complexation takes place is an important parameter in the complexation process, influencing the structures formed.