Preparation and characterization of large unilamellar vesicles mixed with trimethylchitosan (TMC): the effect of polyelectrolyte concentration

Background - The effect of different concentrations of the absorption enhancer Trimethyl Chitosan (TMC) to the physicochemical properties of Large Unilamellar Vesicles (LUV) comprised of L-a-Phospahtidyl Choline (PC) were investigated in the current study. 

Methods - The Degree of Quartenization (DQ) of trimethylchitosan was assessed with nuclear magnetic resonance ( ¹H NMR). The vesicles were characterized by means of Dynamic Light Scattering (DLS), ζ-potential, Differential Scanning Calorimetry (DSC) and Contact Angle Goniometry (CAG) measurements. 

Results - The data showed that the surface charge of the PC liposomes was significantly altered as a function of the TMC concentration, giving evidence of presence of the polyelectrolyte to the liposome’s membrane. Varying the concentration of TMC affected the phase Transition Temperature (T _m) of the lipid, verifying the miscibility of the polyelectrolyte with the lipid bilayer. The association of the polymer with the liposomes was related to the amount of the polyelectrolyte present, reflecting changes to the wettability of the dispersion as measured by CAG. 

Conclusion - The results demonstrated that presence of TMC significantly modified the physical properties of liposomes. Such systems might have a potential use for mucosal delivery (e.g. nasal route of administration).