Star-PDMAEMA--CD-Stabilized Colloidal Gold Nanoparticles: Synthesis, Characterization and pH-Controlled Assembly

Colloidal gold nanoparticles were prepared through in situ reduction in the presence of water-soluble star homopolymer with -cyclodextrin core and poly[2-(dimethylamino) ethyl methacrylate] arms (star PDMAEMA--CD) at ambient temperature. In this process, star PDMAEMA--CD acted as both reducing agent and stabilizing agent for gold nanoparticles. More importantly, the optical properties and the morphology of star-PDMAEMA--CD-stabilized colloidal gold nanoparticles were sensitive to the solution pH due to structural changes of the polymer. Different assemblies can be formed by tuning the pH of the medium. Fourier transform infrared (FT-IR), UV-Vis absorption spectroscopy, transmission electron microscopy (TEM), dynamic laser light scattering (DLS) and X-ray diffraction (XRD) were used to characterize the synthetic gold nanoparticles and the pH-controlled assembly of gold nanoparticles.