Mechanical and transport properties of chitosan-zwitterionic phospholipid vesicles

Chitosan is a polysaccharide that has shown promise in liposomal drug delivery because of certain desirable properties such as muco-adhesivity, biodegradability and low toxicity. In this study, chitosan-bearing 1-stearoyl-2-oleoyl-sn-glycero-3-phosphocholine giant unilamellar vesicles were prepared using inverse phase precursor method to measure their mechanical and transport properties. We show that while an increase in chitosan: lipid molar ratio in the vesicle bilayer at pH 7 led to a substantial increase in its bending modulus, chitosan-mediated change in bending modulus was diminished at pH 4.5. Water permeability across the vesicle bilayer, as well as phospholipid diffusivity within supported lipid bilayers, were also found to decrease with increasing chitosan: lipid molar ratio. Together, these findings demonstrate that incorporation of chitosan in phospholipid bilayers modulates the mechanical and transport properties of liposomes which may affect their in vivo circulation time and drug release rate.