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Abstract: An aqueous suspension of gold nanoparticles of sizes from 20 to 90nm can be conjugated with mercaptosuccinic acid and exposed to a second phase of toluene containing an electrostatic coupler, tetraoctylammonium bromide, to organize the gold particles at the interface between water and toluene. The particles have an amphiphilic character similarly to Janus beads. The thus formed membrane can be transferred to a solid surface to yield centimeter-sized densely packed particle layers. We show that by changing the coupler concentration, the particle distances can be tailored, which modifies the optical properties. [Copyright &y& Elsevier]

Abstract: Polymers of 2-(2-methoxyethoxy)ethyl methacrylate (MDM) were prepared by atom transfer radical polymerization using 2-(2′-bromoisobutyroyloxy)ethyl disulfide as initiator. An aqueous solution of the disulfide-carrying polymer (DT-PMDM) turned to be opaque above certain temperature (22 °C for DT-PMDM ()), which was corresponding to the lower critical solution temperature (LCST) of the polymer. The disulfide-carrying polymer could be accumulated on the surface of gold colloid as a polymer brush as confirmed by the increase in absorbance at 550 nm ascribable to the localized surface plasmon resonance (LSPR). Furthermore, the polymer brush could also be constructed on a monolayer of colloidal gold that had been deposited on a glass plate beforehand. The PMDM brush on both the free and surface-confined gold colloids showed definite temperature responsiveness in the absorbance at 550 nm. Moreover, non-specific adsorption of various proteins to the surface of polymer brush on the glass plate was examined by the absorption increase at 550 nm. The PMDM brush, which had been prepared with the DT-PMDM pretreated with NaBH4, did not adsorb lysozyme significantly below the LCST of the polymer chain, whereas substantially adsorbed the protein above the LCST. These results suggest usability of the polymer brushes with pendent ω-methoxy oligo(ethylene glycol) groups to coat various materials for biomedical applications. [Copyright &y& Elsevier]