title: In situ growth of hollow gold-silver nanoshells within porous silica offers tunable plasmonic extinctions and enhanced colloidal stability.
abstract: Porous silica-coated hollow gold-silver nanoshells were successfully synthesized utilizing a procedure where the porous silica shell was produced prior to the transformation of the metallic core, providing enhanced control over the structure/composition of the bimetallic hollow core. By varying the reaction time and the precise amount of gold salt solution added to a porous silica-coated silver-core template solution, composite nanoparticles were tailored to reveal a readily tunable surface plasmon resonance that could be centered across the visible and near-IR spectral regions (∼445-800 nm). Characterization by X-ray photoelectron spectroscopy, energy-dispersive X-ray spectroscopy, scanning electron microscopy, and transmission electron microscopy revealed that the synthetic methodology afforded particles having uniform composition, size, and shape. The optical properties were evaluated by absorption/extinction spectroscopy. The stability of colloidal solutions of our composite nanoparticles as a function of pH was also investigated, revealing that the nanoshells remain intact over a wide range of conditions (i.e., pH 2-10). The facile tunability, enhanced stability, and relatively small diameter of these composite particles (∼110 nm) makes them promising candidates for use in tumor ablation or as photothermal drug-delivery agents.
authors.affiliation: Department of Chemistry and the Texas Center for Superconductivity, University of Houston , 4800 Calhoun Road, Houston, Texas 77204-5003, United States.
authors.forename: Chien-Hung
authors.initials: CH
authors.lastname: Li
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Jamison
authors.forename: Supparesk
authors.initials: S
authors.lastname: Rittikulsittichai
authors.forename: Tai-Chou
authors.initials: TC
authors.lastname: Lee
authors.forename: T Randall
authors.initials: TR
authors.lastname: Lee
mesh_terms: D003102:Colloids / Q000737:chemistry; D016503:Drug Delivery Systems; D006046:Gold / Q000737:chemistry*; D006801:Humans; D053768:Metal Nanoparticles / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D057145:Nanoshells / Q000737:chemistry* / Q000648:ultrastructure; D010316:Particle Size; D016062:Porosity; D012822:Silicon Dioxide / Q000737:chemistry; D012834:Silver / Q000737:chemistry*; D020349:Surface Plasmon Resonance
chemical_list: D003102:Colloids; D012834:Silver; D006046:Gold; D012822:Silicon Dioxide
keywords: bimetallic; gold−silver; hollow nanoshells; silica-coated; tunable plasmon