Design of Multifunctional Liposomal Nanocarriers for Folate Receptor-Specific Intracellular Drug Delivery.

As a novel carrier for folate receptor (FR)-targeted intracellular delivery, we designed two types of targetable liposomal systems using Pep-1 peptide (Pep1) and folic acid as a cell-penetrating peptide (CPP) and target molecule, respectively. Folate-linked Pep1 (Fol-Pep1) was synthesized by solid phase peptide synthesis (SPPS) and verified using 1H NMR and far-ultraviolet (UV) circular dichroism (CD). The chimeric ligand (Fol-Pep1)-modified liposome (cF-P-L) was prepared by coupling Fol-Pep1 to maleimide-derivatized liposomes at various ratios. The dual ligand (folate and Pep1)-modified liposome (dF/P-L) was prepared by separately attaching both ligands to the liposomal surface via a short (PEG2000) or long (PEG3400) linker. The physical and conformational characteristics including vesicle size, zeta potential, and the number of conjugated ligands were determined. Intracellular uptake specificities of various fluorescent probe-containing cF-P-L and dF/P-L systems were assessed using FR-positive HeLa and ...