Cholesterol Succinyl Chitosan Anchored Liposomes As A Novel Carrier For Epirubicin

The purpose of this study was to evaluate the functions of cholesterol succinyl chitosan (CHCS), which has a hydrophobic moiety, as an anthoring material for liposomes to be loaded with the anticancer drug, Epirubicin (EPB).Three different Substitution Degrees (DS) of cholesterol moiety of CHCS conjugates were determined by Colloid Titration method and the DS of CHCS conjugates were 2.80 % (CHCS-1), 5.85 % (CHCS-2) and 8.0 % (CHCS-3), respectively. The liposomes (phosphatidylcholine/cholesterol (molar ratio) = 2/1) were prepared by the thin-film hydration method. Drug encapsulation was carried out using a modified pH gradient method.CHCS-1 anchored EPB liposomes (1-CHEL),CHCS-2 anchored EPB liposomes (2-CHEL) and CHCS-3 anchored EPB liposomes (3-CHEL) were prepared by incubation method. CHEL were almost spherical in shape and had a classic shell-core structure. The existence of a thick polymer layer on the surface of the liposomes was confirmed by the increase in particle size and zeta potential, especially for the CHEL.Compared with plain EPB liposomes (EL) and chitosan (CS) coated EPB liposomes (CEL), CHEL significantly sustained the release of EPB in vitro (both in PBS (pH 7.4) and 1 % (V/V) aqueous fetal bovine serum (FBS)), and the release rate decreased when the DS of cholesterol moiety increased. It could be presumed based on the experiment result that CHCS involved anchoring the hydrophobic moiety of CHCS to the phospholipid bilayer. But when CS was used as the coating polymer, the resulting coating layer was not thick owing to the coating mechanism, simple physical adsorption.It could be presumed that the cholesterol moieties of CHCS embedded into the phospholipid bilayer to form CHEL, which would increase the stability of liposomes. Our experiment result certified that the CHEL could increase stabilities of liposomes more obviously than CS in vitro. From this preliminary study in vitro, this novel kind of liposomes has potential to be applied in drug delivery systems.