Delivering the medicine at the right place inside the body, it also needs to be at the right location at the right time, pass the correct barriers, and pharmaceutical components need to keep their activity.
While targeting is often associated with having the nanocarriers modified with the right recognition peptides or sequences, still tuning the translocation of these carriers across cellular membranes, biological barriers from the bloodstream to the actual tissue such as the blood brain barrier amongst others, are of great importance.