Chitosan is a polysaccharide with applicability in many areas due to its high biocompatibility and biodegradability. In some of these applications, chitosan interaction occurs directly with cells, mainly through electrostatic interactions between positive charges of the polyelectrolyte and the "polar head" of the negatively charged phospholipids of the membrane. Even though the electrostatic are the main interaction forces, they are not the only form of interaction between chitosan and the cell membrane. In this project we plan to investigate effects that act in synergy with the electrostatic interactions to understand the mechanisms of chitosan action. This will be pursued by producing and characterizing chitosan derivatives through the acylation reaction, which are soluble in chloroform. Then these derivatives will be used to obtain Langmuir films either in their neat form or mixed with phospholipids. In this synthesis the hydroxyl groups of chitosan will be replaced by acyl chains with 14 or 16 carbons, but the amine group will be preserved. We shall therefore be able to evaluate: i) the contribution from the hydroxyl groups in the hydrogen bonds and ii) the quantifity of charged groups (amine) at the interface interacting with the membranes. It is known from the literature that the polymer chain arrangement is essential for the interaction with the membrane models. For this reason, we shall evaluate and control the conformation of chitosan in solution, verifying its effect on the interaction with phospholipid Langmuir films, with a possible preferential orientation of chitosan at the interface.
News published in Agência FAPESP Newsletter about the scholarship: