Self-assembly of gold nanoparticles in a block copolymer aggregate template driven by hydrophobic interactions

We have investigated various self-assembled structures of gold nanoparticle (AuNP)-block copolymer complexes in aqueous solution. Depending on the micellar phase of the two kinds of block copolymer mixtures, the AuNPs were successfully entrapped in the hydrophobic region of the block copolymer micelles, and this is driven by hydrophobic interactions. Small angle neutron scattering (SANS) measurements revealed that the AuNP-polymer complex formed various nanostructures, such as spherical, cylindrical and vesicular structures, and that the AuNPs were localized in the hydrophobic region (which is the core part and the inner layer for the spherical and cylindrical micelles and vesicles, respectively) of the micelles, and this is consistent with the results of TEM measurements. In particular, for the vesicular structures, the AuNPs were localized in the hydrophobic region as a form of the single layered structure. This study provides an easy and novel method to entrap the AuNP complex and control its localized structure in soft materials without complicated procedures. In addition, AuNPs entrapped in the unilamellar polymeric vesicles can be utilized as imageable drug carriers, carriers for catalysts, drug or enzyme deliverers and as nanoreactors or nanocarriers.