Challenges in design of translational nanocarriers.

Cancer drug delivery achieving high therapeutic efficacy and low side effects requires a nanocarrier to tightly retain the drug, efficiently reach the tumor, then quickly enter the tumor cells and release the drug. Furthermore, the nanocarrier intended for clinical applications should use materials safe as pharmaceutical excipients and its formulation (nanomedicine) should have good manufacture processes with scale-up ability. Thus, the challenge is to design safe, approvable, and easily scaled-up nanocarriers that simultaneously meet the two pairs of requirements of 'drug retention in circulation versus intracellular release' and 'stealthy in circulation versus sticky (cell-binding) in tumor' at the right places in order to deliver a cytosolic drug dose lethal to cancer cells with minimized side effects. Herein, we briefly review these elements aimed at promoting developments of translational nanocarriers.