Polymeric micellar clusters formed from amphiphilic carbohydrate polymers and their uses in formulating drugs is disclosed, and in particular the finding that amphiphilic carbohydrate polymers are capable of self assembling to form micellar clusters in which the carbohydrate amphiphiles aggregate into hierarchically organized micellar clusters of individual aggregates. The micellar clusters may be transformed into stable nanoparticles with drugs, especially hydrophobic drugs that have poor aqueous solubility, and may improve the transfer of hydrophobic drugs across biological barriers.