title: Metallic Nanoparticle Block Copoloymer Vesicles with Enhanced Optical Properties.
abstract: The fabrication and characterization of template silver nanoshell structures and the encapsulation of gold nanoparticles using biocompatible poly(oxyethylene)-poly(butylene) diblock co-polymer vesicles is described in this work. These vesicles have a narrow diameter size distribution around 200 nm. Silver nanoparticles (Ø = 1-10 nm) functionalized with decanethiol were successfully entrapped in the hydrophobic membrane and non-functionalized gold nanoparticles (Ø = 3.0-5.5 nm) were encapsulated in the vesicle core. Transmission Electron Microscopy confirms the localisation of the particles; silver functionalized nanoparticles appear to thicken the vesicle membrane as shown with TEM image analysis. The enhancement of the optical properties is confirmed using transmission spectrophotometry; the 430 nm plasmon resonance peak of the silver nanoparticles was replaced by a broader extinction spectrum to beyond 700 nm (O.D. = 0.8). For a number density of 4.8 x 1012mL-1the scattering cross section was calculated to be 0.92 x 10-4μm² with a scattering coefficient of 0.44 mm-1. The measurements indicate scattering cross section of 3.8 x 10-5μm², attenuation coefficient of 0.18 mm-1and extinction efficiency equal to 1.2 x 10-3. Stable and biocompatible block co-polymer vesicles can potentially be used as plasmon-resonant optical contrast agents for biomedical applications.
authors.affiliation: Institute of Biotechnology, University of Cambridge, Tennis Court Rd, CB21QT, Cambridge, UK. juanleonardo@gmail.com.
authors.forename: Juan Leonardo
authors.initials: JL
authors.lastname: Martinez-Hurtado
keywords: block copolymer; encapsulation; metallic nanoparticle; optical properties