Amphiphilic beta-Cyclodextrin-Based Star-Like Block Copolymer Unimolecular Micelles for Facile In Situ Preparation of Gold Nanoparticles

Multifunctional polymer unimolecular micelles, which are used as templates to fabricate stable gold nanoparticles (GNPs) in one-step without external reductant, have been designed and prepared. Amphiphilic 21-arm star-like block copolymers beta-cyclodextrin-{poly(lactide)-poly(2-(dimethylamino) ethyl methacrylate)-poly[oligo(2-ethyl-2-oxazoline) methacrylate]}(21) [beta-CD-(PLA-PDMAEMA-PEtOxMA)(21)] and the precursors are synthesized by the combination of ring-opening polymerization (ROP) and activators regenerated by electron transfer atom transfer radical polymerization (ARGET ATRP). The tertiary amine groups of PDMAEMA block reduce the AuCl4- counterion to zerovalent gold in situ, and these gold atoms combine mutually to form final GNPs. GNPs with relatively small size and narrow size distribution can be obtained in longer DMAEMA block copolymer, larger molar ratio of DMAEMA to HAuCl4 and smaller absolute concentrations of both polymer and HAuCl4. These results showed that the unimolecular micelles can be used as templates for preparing and stabilizing GNPs in situ without any external reducing agents and organic solvents, suggesting that the nanocomposite systems are latent nanocarriers for further biomedical application. (C) 2015 Wiley Periodicals, Inc.