Folate-PEG coated cationic modified chitosan--cholesterol liposomes for tumor-targeted drug delivery.

In this paper, a folate-PEG coated polymeric liposome (FPL) formed from octadecyl-quaternized lysine modified chitosan (OQLCS) and cholesterol has been prepared successfully. The OQLCS and its derivatives were characterized using (1)H NMR and infrared spectrum analysis. The FPLs properties were extensively studied by dynamic light scattering (DLS), fluorescence spectroscopy, and transmission electron microscopy (TEM). Due to the amphiphilic property and positive zeta potential of OQLCS, the OQLCS and cholesterol can form stable core-shell FPLs with small size (effective diameter: 163.5 nm) and narrow distribution (polydispersity: 0.108) in aqueous solutions. The PLs could form multi-lamellar structure similar to that of traditional liposomes prepared from phosphatidylcholine/cholesterol (PC/Chol). Compared with traditional liposome, calcein-loaded Polymeric Liposome exhibited high encapsulation efficiency in aqueous solution and slow, controlled release under different pH conditions. Most important, in cellular uptake experiment, folate coated FPLs showed significant higher uptake by MCF-7 cells as compared to FPLs without folate and traditional liposomes, because of the folate-receptor mediated endocytosis. The data suggest that the folate-PEG coated polymeric liposomes (FPLs) may be a useful drug delivery system.