Folate and TAT peptide co-modified liposomes exhibit receptor-dependent highly efficient intracellular transport of payload in vitro and in vivo.

PURPOSE: Using different chain lengths of PEG as linkers to develop a novel folate (FA) and TAT peptide co-modified doxorubicin (DOX)-loaded liposome (FA/TAT-LP-DOX) and evaluate its potential for tumor targeted intracellular drug delivery.

METHODS: FA/TAT-LP-DOX was prepared by pH gradient method and post-insertion method and the optimal ligand density was screened by MTT assay. In vitro evaluation was systematically performed through cytotoxicity assay, cellular uptake studies, subcellular localization and cellular uptake mechanism in folate receptor (FR) over-expressing KB tumor cells. In vivo tumor targeted delivery of FA/TAT-LP-DOX was also studied by in vivo fluorescence imaging in a murine KB xenograft model.

RESULTS: The particle size and zeta potential determination indicated that FA and TAT were successfully inserted into the liposome and cationic TAT peptide was completely shielded. With the optimal ligand density (5% of FA and 2.5% TAT), the FA/TAT-LP-DOX exhibited improved cytotoxity and cellular uptake efficiency compared with its single-ligand counterparts (FA-LP-DOX and PEG/TAT-LP-DOX). Competitive inhibition and uptake mechanism experiments revealed that FA and TAT peptide played a synergistic effect in facilitating intracellular transport of the liposome, and association between FA and FA receptors activated this transport process. In vivo imaging further demonstrated the superiority of FA/TAT-LP in tumor targeting and accumulation.

CONCLUSIONS: Folate and TAT peptide co-modified liposome using different chain lengths of PEG as linkers may provide a useful strategy for specific and efficient intracellular drug delivery.