Surface Engineering of Liposomal Formulations for Targeted Drug Delivery

Liposomes, basically including lecithin and cholesterol, are classic nanovesicles to treat some diseases clinically. As the first FDA approved nanomedicine, Doxil® (Doxorubicin HCl Liposome Injection) is a successful formulation to inhibit the development of some cancer and improve the life time of the patients after tumor surgery [1]. However, the non-specific accumulation of liposomes in Reticuloendothelial System (RES) impacts the normal function of uninvolved organs such as liver, spleen and bone marrow [2]. To improve the targeting of the liposomes, surface engineering of liposomes for controlled drug delivery has been widely investigated [3-6]. Small molecules such as sugar and folic acid were conjugated on the surface of liposomes to increase the uptake by cells [7]. Various ligands including proteins and peptides linked with artificial phospholipid in the bilayers of liposomes also greatly enhanced the affinities of carriers to the specific tissue [8,9].