In a recent breakthrough by Cui et. al drug amphiphiles were synthesized and they could effectively control the amount of drug in nanostructures but what missing from there was encapsulation of drug itself during self assembly of DA into nanostructures. They have synthesized nanofibers but as far i know by manipulating the concentration of amphiphiles during their self-assembly it is possible to control the type of nanostructure formed. http://www.nsf.gov/discoveries/disc_summ.jsp?cntn_id=127536&org=NSF
We can synthesize drug amphiphiles with targeting ligand on hydrophillic part and drug as hydrophobic part, and use this to encapsulate drug itself while allowing them to self-assemble into different nanostructres like nanoparticles or nanofibers. The drug content would be higher as the nanostructures are made from drug itself and drug is encapsulated too.