The development of site-specific drug delivery nanocarriers based on receptor mediation.

Since they were first reported in 1980, site-specific drug delivery nanocarriers have progressed greatly with the development of nanotechnology and biotechnology, especially in the anti-tumor field. Currently, some of the ligand peptides like RGD have become hot targeting molecules with extensive academic studies and some receptor-medicated nanocarriers are now in clinical trials. Homing peptides have been the preferred ligands thus far due to their low molecular weight, low antigenicity, high modification ratios and low interference in vivo. The major benefit of receptor-mediated nanocarriers over passive ones may be their accumulation within tumors for longer period of time due to their binding to and/or their uptake by cancer cells, preventing them from fast redistribution into systemic circulation. The studies on receptor-mediated nanocarriers are very dynamic currently, advancing gradually from these against non-therapeutic targets to these against therapeutic targets. And recently, more studies were focused on these systems against multiple receptors and the combination therapies with receptor-mediated nanocarriers. However, we still face great challenges, especially in the understanding of receptors, the key issue for receptor-mediated delivery. This review presents the past and ongoing studies on various types of drug delivery systems based on receptor mediation, discusses the prospective and challenges, and introduces the possible trend of study in the future.