The effects of ligand distribution and density on the targeting properties of dual-targeting folate/biotin Pluronic F127/Poly (lactic acid) polymersomes

Abstract

Targeted drug delivery systems modified with two or more ligands were expected to have better anti-tumor ability than those with just one ligand due to the complexity and heterogeneity of tumors. Thus, dual-targeting Pluronic/poly (lactic acid) polymersomes containing biotin (BT) and folic acid (FA) ligands (BT/FA-F127-PLA) were designed to study their targeting properties over human ovarian cancer cells (OVCAR-3). Two kinds of dual-ligand targeting polymersomes, BT/FA-F127-PLA and (BT + FA)-F127-PLA, were prepared to study the effect of the dual-ligand distribution on the cell targeting of polymersomes. BT/FA-F127-PLA had two ligands distributed in the same polymersomes whereas (BT + FA)-F127-PLA had two ligands distributed in different polymersomes. The in vitro cytotoxicity and cellular uptake, and in vivo pharmacokinetic behaviors of BT/FA-F127-PLA were superior to those of (BT + FA)-F127-PLA. It suggested that biotin and folate ligands distributed on the same polymersomes could have the targeting effect of synergistic promotion. Further experiments on cell uptake mechanisms of polymersomes showed that the uptake of targeted polymersomes was associated with energy-dependent endocytosis, involving clathrin, caveolin protein, macropinocytosis and ligand receptor-mediated endocytosis. In addition, the effect of different density ratios of dual ligands for BT/FA-F127-PLA was further studied. The results showed that the cellular targeting effect of BT/FA-F127-PLA was the strongest when the molar ratio of biotin to folic acid was 7.5 %: 7.5 %. In conclusion, BT/FA-F127-PLA dual-targeting polymersomes could be good candidates as targeted drug delivery carriers.