INTERACTIONS OF CHITOSAN-BASED NANOPARTICLES WITH BIO-INSPIRED MEMBRANES.

Chitosan is a natural copolymer derived from the deacetylation of chitin. Because of its specific physicochemical properties, chitosan is a perfect material to be used in bioengineering and biomedicine. In this study, we demonstrated how chitosan is able to affect the lipid order and organisation in biomimetic membranes. We formed large unilamellar vesicles (LUVs) composed of different lipids and their mixtures mimicking the lipid architecture of mammalian plasma membranes. Lipid order was probed by Laurdan spectroscopy measurements at physiological temperature. We studied LUVs composed of egg phosphatidylcholine (ePC) exhibiting lipid bilayer in liquid-disordered phase (Ld), egg sphingomyelin (eSM)/cholesterol (Chol) in liquid-ordered phase (Lo), and ePC/eSM/Chol mixtures representing Ld/Lo phase coexistence. The ternary mixture compositions mimic the plasma membrane organisation and formation of raft-like domains with different sizes. Membrane rafts are known to be involved in crucial cellular physiological events in health and disease. LUVs were treated by increasing chitosan concentration and lipid order was assessed by Laurdan fluorescence spectroscopy. The interaction of chitosan with lipid membranes induces an increase in the lipid order independently of the lipid phase state. The highest increase in the lipid order was observed for the Ld phases, whereas, the lowest one was detected for the Lo phase. We suggested molecular mechanisms of interaction of chitosan with the main lipid classes and their phase state. [ABSTRACT FROM AUTHOR]