Gold nanoparticles decorated by amphiphilic block copolymer as efficient system for drug delivery.

A drug delivery system based on gold nanoparticles (Au NPs) stabilized by an thiol-functionalized amphiphilic diblock copolymer was developed. The copolymer, poly(ethylene glycol)-b-poly(n-butyl acrylate) (MPEG-b-PBA), was synthesized by Reversible Addition-Fragmentation Transfer (RAFT) polymerization and the thiocarbonylthio group at the end of the hydrophobic block PBA was further reduced to thiol group. Pyrene, used as a model molecule for the hydrophobic drugs, was loaded in the hydrophobic interior of the shell around Au NPs by physical entrapment. The analysis performed by UV-Vis spectrophotometer show that the obtained Au NPs-pyrene nanocomposites have good stability in the aqueous solution and high drug loading capacity in comparison with Au NPs decorated with small molecular ligands. In addition, both their loading capacity and release behavior were found closely related to the chain length of hydrophobic block. In conclusion, we report here a versatile and simple procedure to fabricate Au NP-polymer hybrids that is applicable to various amphiphilic copolymers synthesized by RAFT polymerization and useful to produce efficient Au NP based drug carriers.