Recent developments in lipid-based pharmaceutical nanocarriers.

Within the broad spectrum of nanoparticulate carriers, polymeric and lipid-core micelles, liposomes, solid nanoparticles and many others have demonstrated great biological properties which make them excellent pharmaceutical delivery systems. In particular, micelles and liposomes have been shown to have good longevity in the blood that allows their accumulation in pathological areas with a compromised vasculature; can possess specific targeting to disease sites when various targeting ligands are attached to the surface of the nanocarriers or to surface-attached cell-penetrating molecules (like TAT peptide) to enhance intracellular penetration; possess stimulus-sensitivity allowing for drug release from the carriers under certain pathological conditions; and show contrast properties with carrier loading of various contrast materials that allow for direct carrier visualization in vivo. The engineering of "multifunctional pharmaceutical nanocarriers" based on the combination of several useful properties in the same system can significantly enhance the efficacy of many therapeutic and diagnostic protocols. This review considers the current status and next future directions in the emerging area of nanomedicine with particular attention to two lipid-based nanoparticulate systems: liposomes and micelles.