Comparative assessments of crucial factors for a functional ligand-targeted nanocarrier.

We previously developed a ligand-targeted liposome, referred to as a prohibitin-targeted nanoparticle (PTNP), for specifically delivering encapsulated drugs into vascular endothelial cells in adipose tissue. In this study, we explored the critical factors for the successful development and application of ligand-targeted nanocarriers through comparative assessments of PTNP prepared by the reverse-phase evaporation (REV) and lipid film hydration (HYD) methods with reference to physicochemical characteristics and in vivo and in vitro behavior. The in vivo delivery and therapeutic properties of HYD-PTNP were dramatically inferior to those of REV-PTNP, although the size, ζ-potential, fixed aqueous layer thickness and surface ligand density of the two preparations were similar. Circular dichroism spectral analyses revealed that the irreversible alteration in ligand conformation was caused by the organic solvent used to prepare the thin lipid film. In addition, perturbation of the ligand by the organic solvent resulted in a reduced internalization of PTNP into adipose endothelial cells. Alteration of the ligand conformation did not appear to affect the physicochemical characteristics of nanocarriers. Therefore, appropriate handling of ligands and appropriate evaluation of their conformations are critical for the successful development and application of such targeted nanocarriers.