Synthesis of Hollow Polymer Nanocapsules Exploiting Gold Nanoparticles as Sacrificial Templates

This paper describes a new approach for the synthesis of hollow functional polymer nanocapsules, which exploits gold nanoparticles as sacrificial templates. Two different functional diblock polymers have been coassembled on the gold nanoparticles prior to gold removal. The block polymers (made by RAFT polymerization) consisted of a biocompatible polymer segment, either (poly(oligoethylene glycol) acrylate, P(OEG-A), or poly(hydroxylpropylacrylamide), P(HPMA) and a cross-linkable segment comprised of an alternating copolymer of styrene (Sty) and maleic anhydride (MA), (Sty-alt-MA). The block copolymers were assembled onto the GNP surfaces using a grafting onto methodology exploiting the high affinity of the RAFT end-groups for the gold surface. The anhydride group Was utilized to cross-link the polymer layer. Finally, the gold cores were removed using aqua regia without affecting the integrity of the polymers chains or the nanocapsules. All reaction and assembly steps were characterized by employing a range of techniques, such as TEM, XPS, ATR-FTIR, DLS, and UV-visible spectroscopy.